International Technology Research Institute
                                                               World Technology (WTEC) Division




WTEC Panel Report on

Wireless Technologies and Information Networks



                                 Anthony Ephremides, Panel Chair
                                 Tatsuo Itoh, Vice Chair
                                 Raymond Pickholtz, Vice Chair
                                 Magdy Iskander
                                 Linda Katehi
                                 Ramesh Rao
                                 Wayne Stark
                                 Jack Winters



                                          July 2000




                              International Technology Research Institute
                                              R.D. Shelton, Director
                       Geoffrey M. Holdridge, WTEC Division Director and ITRI Series Editor

                                        4501 North Charles Street
                                     Baltimore, Maryland 21210-2699

                   WTEC Panel on Wireless Technologies and Information Networks
   Sponsored by the National Science Foundation, the Department of Defense (OSD), the Defense Advanced Research
   Projects Agency, the Office of Naval Research, the National Institute of Standards and Technology and the National
                        Aeronautics and Space Administration of the United States government.

Dr. Anthony Ephremides (Chair)                                                               Dr. Wayne Stark
                                               Dr. Linda Katehi
University of Maryland                                                                       University of Michigan
                                               University of Michigan
Rm. 2333                                                                                     1301 Beal Avenue
                                               College of Engineering
AV Williams Building                                                                         Ann Arbor, MI 48109-2122
                                               2105 Robert H. Lurie Eng. Center
College Park, MD 20742                         1221 Beal Avenue
                                                                                             Dr. Jack Winters
                                               Ann Arbor, MI 48109-2102
Dr. Magdy Iskander                                                                           AT & T Labs Research
Electrical Engineering Dept.                                                                 100 Schulz Drive
                                               Dr. Raymond Pickholtz (Vice Chair)
University of Utah                                                                           Red Bank, NJ 07701
                                               George Washington University
50 S. Central Campus Dr.                       Dept. EE/Comp. Science
                                               Phillips Hall, 6th Fl.
Room 3280
                                               Washington, DC 20052
Salt Lake City, UT 84112

                                               Dr. Ramesh Rao
Dr. Tatsuo Itoh (Vice Chair)
                                               UCSD
Dept. of Electrical Engineering
                                               Dept. of Elect./Comp. Engineering
UCLA
                                               9500 Gilman Drive
405 Hilgard Avenue
                                               M/C 0407
Los Angeles, CA 90095-1594
                                               La Jolla, CA 92093-0407




    Some site reports contained in this volume also were contributed by the following WTEC sponsor representatives:
    Dennis Friday (NIST), Joanne Maurice (AFOSR/AOARD), Nader Moayeri (NIST), and Leo Young (DOD/OSD).




                         INTERNATIONAL TECHNOLOGY RESEARCH INSTITUTE
                                  World Technology (WTEC) Division

   WTEC at Loyola College (previously known as the Japanese Technology Evaluation Center, JTEC) provides assessments
   of foreign research and development in selected technologies under a cooperative agreement with the National Science
   Foundation (NSF). Loyola's International Technology Research Institute (ITRI), R.D. Shelton, Director, is the umbrella
   organization for WTEC. Elbert Marsh, Deputy Assistant Director for Engineering, is NSF Program Director for WTEC.
   Several other U.S. government agencies provide support for the program through NSF.

   WTEC's goal is to inform U.S. scientists, engineers, and policymakers of global trends in science and technology. WTEC
   assessments cover basic research, advanced development, and applications. Panels of typically six technical experts
   conduct WTEC assessments. Panelists are leading authorities in their field, technically active, and knowledgeable about
   U.S. and foreign research programs. As part of the assessment process, panels visit and carry out extensive discussions
   with foreign scientists and engineers in their labs.

   The ITRI staff at Loyola College help select topics, recruit expert panelists, arrange study visits to foreign laboratories,
   organize workshop presentations, and finally, edit and disseminate the final reports.

   Dr. R.D. Shelton                                Mr. Geoff Holdridge                            Dr. George Gamota
   ITRI Director                                   WTEC Division Director                         ITRI Associate Director
   Loyola College                                  Loyola College                                 17 Solomon Pierce Road
   Baltimore, MD 21210                             Baltimore, MD 21210                            Lexington, MA 02173

                                                WTEC Study on

      WIRELESS TECHNOLOGIES AND INFORMATION NETWORKS


                                              FINAL REPORT


                                                     July 2000


                                               Anthony Ephremides, Panel Chair
                                               Tatsuo Itoh, Vice Chair
                                               Raymond Pickholtz, Vice Chair
                                               Magdy Iskander
                                               Linda Katehi
                                               Ramesh Rao
                                               Wayne Stark
                                               Jack Winters




ISBN 1-883712-58-0
This document was sponsored by the National Science Foundation (NSF), the Department of Defense (OSD, DARPA,
and ONR), the Department of Commerce (National Institute of Standards and Technology), and the National Aeronautics
and Space Administration of the U.S. government under NSF Cooperative Agreement ENG-9707092, awarded to the
International Technology Research Institute at Loyola College in Maryland. The government has certain rights to this
material. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors
and do not necessarily reflect the views of the United States government, the authors' parent institutions, or Loyola
College.

                                                  ABSTRACT
This report reviews the status of wireless technologies and information networks around the world, with
particular focus on comparisons between Europe, Japan, and the United States. Specific topics include
coding, modulation and multiple access; switching and routing; channel characterization and propagation
models; hardware for RF front-end; smart antennas; and holistic design of wireless systems. The study
includes site reports for visits conducted by panel members to leading research laboratories and universities
in Europe and Japan. The panel concluded that three major areas of technology must figure prominently in
additional research. These areas include the following: (1) hardware integration and the "system-on-a-
chip"; (2) the exploitation of spatial diversity by smart antennas; (3) design by vertical integration on
software platforms.

                                        ACKNOWLEDGEMENTS
I would like to thank the U.S. government sponsors of this study: the National Science Foundation, the
National Institute of Standards and Technology (NIST), the Office of the Secretary of Defense (OSD), the
Office of Naval Research, the Defense Advanced Research Projects Agency, and the National Aeronautics
and Space Administration. Special thanks are due to our sponsor representatives who traveled with the panel
in Japan and Europe, and who authored many of the site reports included in appendices C and D: Dennis
Friday and Nader Moayeri (NIST), Leo Young (OSD), and Joanne Maurice (AFOSR). We are very much
indebted to our panel chair, Anthony Ephremides, for his leadership over the course of the study. All of the
panelists are due great credit for their contributions of time and intellect. It was both an honor and a pleasure
to work with this group. Finally, we are extremely grateful to all of our hosts in Japan and Europe, and to
the participants in the March 1999 U.S. review workshop, for sharing their activities and insights with us.
Geoffrey M. Holdridge, WTEC Division Director and ITRI Series Editor


                    International Technology Research Institute (ITRI)
                               R. D. Shelton, Principal Investigator, ITRI Director
                                     George Mackiw, Deputy ITRI Director
                                    George Gamota, ITRI Associate Director
                                    J. Brad Mooney, TTEC Division Director
                                   Robert Margenthaler, BD Division Director

                                 World Technology (WTEC) Division
                   Geoffrey M. Holdridge, WTEC Division Director and ITRI Series Editor
                                   Bobby A. Williams, Financial Officer
                             Christopher McClintick, Wireless Study Manager
                        Roan E. Horning, Head of Information Technologies Section
                               Michael Stone, LINUX Systems Administrator
                                   Robert Tamburello, Student Assistant
                                         Judith M. Dobler, Editor
                                    Aminah Grefer, Editorial Assistant
             Jerry Whitman and Stella Lin Whitman, Advance Work for Japan and Europe Trips
                             Hiroshi Morishita, WTEC Japan Representative

Copyright 2000 by Loyola College in Maryland except as elsewhere noted. This work relates to NSF Cooperative
Agreement ENG-9707092. The U.S. government retains a nonexclusive and nontransferable license to exercise all
exclusive rights provided by copyright. The ISBN number for this report is 1-883712-58-0. This report is distributed by
the National Technical Information Service (NTIS) of the U.S. Department of Commerce as NTIS PB2000-105895. A
list of available JTEC/WTEC reports and information on ordering them from NTIS is included on the inside back cover
of this report.

                                                                                                                                                                     i


                                                         TABLE OF CONTENTS
Table of Contents ............................................................................................................................................... i
List of Figures .................................................................................................................................................. iv
List of Tables..................................................................................................................................................... v

Executive Summary....................................................................................................................................... vii

1.           Introduction
             Anthony Ephremides

             Introduction ......................................................................................................................................... 1
             Approach ............................................................................................................................................. 2

2.           Coding, Modulation, and Multiple-Access
             Wayne Stark

             Overview ............................................................................................................................................. 5
             Background ......................................................................................................................................... 5
             Coding and Modulation....................................................................................................................... 8
             Multiple-Access Techniques ............................................................................................................. 12
             Comparative Analysis ....................................................................................................................... 13
             Conclusions ....................................................................................................................................... 13
             References ......................................................................................................................................... 14

3.           Switching and Routing in Wireless Networking
             Raymond L. Pickholtz

             Preface ............................................................................................................................................... 15
             Introduction ....................................................................................................................................... 15
             Broadband and Internet Access......................................................................................................... 17
             Concluding Remarks......................................................................................................................... 21
             Acknowledgment .............................................................................................................................. 22

4.           Channel Characterization and Propagation Models for Wireless Communication Systems
             Magdy F. Iskander

             Introduction ....................................................................................................................................... 23
             Propagation Models for Urban Environment .................................................................................... 24
             Key Research Issues.......................................................................................................................... 30
             References ......................................................................................................................................... 30

5.           Hardware for RF Front-End of Wireless Communication
             Tatsuo Itoh, Linda Katehi

             Introduction ....................................................................................................................................... 33
             CMOS Technologies and Silicon Bipolar Transistors ...................................................................... 34
             III-V Devices and Circuits ................................................................................................................ 37
             SiGe Devices and Circuits................................................................................................................. 39
             GaN Devices and Circuits ................................................................................................................. 41
             Millimeter-wave CPW MMIC .......................................................................................................... 41
             High Q Components and Filters........................................................................................................ 42
             Packaging and Integration................................................................................................................. 43

                                                               Table of Contents
ii

     Amplifiers .......................................................................................................................................... 47
     Antennas ............................................................................................................................................ 48
     Concluding Remarks..........................................................................................................................49
     Technology Assessment .................................................................................................................... 51

6.   Smart Antennas
     Jack H. Winters

     Introduction........................................................................................................................................ 53
     Smart Antenna Description................................................................................................................53
     Future Wireless System Requirements .............................................................................................. 54
     Smart Antenna Advantages................................................................................................................55
     Use Of Smart Antennas ..................................................................................................................... 55
     Key Research Issues .......................................................................................................................... 55
     Concluding Remarks..........................................................................................................................57
     Technology Assessment .................................................................................................................... 58

7.   Holistic Design of Wireless Systems
     Ramesh Rao

     Introduction........................................................................................................................................ 59
     Software Radios.................................................................................................................................59
     Power and Energy Management ........................................................................................................ 62
     Integrated Approaches to Wireless System Design ........................................................................... 63
     Summary ............................................................................................................................................ 64
     Reference ........................................................................................................................................... 64

APPENDICES

A.   Professional Experience of Panelists .............................................................................................. 65

B.   Professional Experience of Other Team Members ....................................................................... 70

C.   Site Reports--Europe
     Alcatel ................................................................................................................................................ 72
     Centro Studi E Laboratori Telecomunicazioni (CSELT)...................................................................74
     Daimler-Chrysler Research Center, Ulm ........................................................................................... 76
     Ericsson Radio Systems AB .............................................................................................................. 80
     Filtronic PLC. .................................................................................................................................... 83
     GMD FOKUS .................................................................................................................................... 87
     German National Research Center for Information Technologies (GMD)........................................90
     IBM Zurich Laboratory ..................................................................................................................... 93
     Institute of Mobile and Satellite Communication Techniques (IMST)..............................................96
     Nokia................................................................................................................................................ 102
     Philips Research Laboratories..........................................................................................................104
     Site Reports--Japan
D.
     Advanced Telecommunications Research-International (ATR-I) ................................................... 107
     Fujitsu Laboratories ......................................................................................................................... 110
     KDD Research and Development Laboratories...............................................................................112
     Matsushita Electric Industrial Co., Ltd ............................................................................................ 114
     Matsushita Research Institute Tokyo (MRIT) ................................................................................. 118
     Mitsubishi Electric Corporation.......................................................................................................122

                                                             Table of Contents                                                                         iii

     Murata Manufacturing Company .................................................................................................... 124
     NEC C&C Media Research Laboratories ....................................................................................... 129
     NEC Tsukuba Research Laboratories ............................................................................................. 131
     Nippon Telegraph and Telephone Corporation (NTT) ................................................................... 134
     NTT DoCoMo, Wireless Laboratories............................................................................................ 14 0
     Tohoku University .......................................................................................................................... 142
     Toshiba Corporation........................................................................................................................ 144
     Yokosuka Research Park (YRP) ..................................................................................................... 147
E.   Glossary.......................................................................................................................................... 149

iv


                                                            LIST OF FIGURES
2.1    The development of a variety of communication systems is shown as a function of data rates
       and user mobility/cell sizes. ................................................................................................................... 8
2 .2   Possible transmission rates versus signal-to-noise ratios for an additive white Gaussian noise
       channel. ....................................................................................................................... ........................... 9
2.3    Received signal strength as a function of time for vehicle velocity 10 mph. ....................................... 10
2.4    Possible transmission rates versus signal-to-noise ratios for a Rayleigh fading channel. .................... 10

3.1    Four way convergence.......................................................................................................................... 16
3.2    Vision of a seamless wireless network. ................................................................................................ 16
3.3    Second generation (GSM/CDMA) network architecture. .................................................................... 17
3.4    GPRS packet format. ......................................................................................................... ................... 18
3.5a   GPRS architecture. ........................................................................................................ ....................... 19
3.5b   GPRS network...................................................................................................................................... 19
3.5c   GPRS routing. ............................................................................................................. ......................... 19
3.6    Network architecture: Wireless ATM system. ..................................................................................... 20

4.1    Fluctuations of the electric field ........................................................................................................... 25
4.2    Coverage distribution in an indoor environment.................................................................................. 26
4.3    A photograph and schematic diagram of the adaptive/diversity antenna measurement system ........... 26
4.4    Microcell of delay profile in a parking lot............................................................................................ 27
4.5    Schematic of the stratospheric wireless access network in Japan. ....................................................... 28

5.1    An example of a silicon-on-anything circuit by Philips Research Laboratory..................................... 35
5.2    Double-poly transistor by Philips Research Laboratory....................................................................... 35
5.3    nMOSFET characteristics by NEC....................................................................................................... 36
5.4    Transmission lines on an Si substrate used by NEC............................................................................. 36
5.5    Recent and projected trends for AD conversion for 1990-2002........................................................... 37
5.6    Daimler-Chrysler InP-based HEMTs. ......................................................................................... ......... 37
5.7    TRW 190 GHz InP HEMT low noise amplifier................................................................................... 3 8
       TRW W-band In-P HEMT power amplifier......................................................................................... 38
5.8
       NEC two-stage mushroom gate HEMT................................................................................................ 39
5.9
       NEC high fmax HBT technology............................................................................................................ 39
5.10
5.11   Comparison of GaAs and SiGe .............................................................................................. .............. 40
5.12   World record performance of SiGe HBTs............................................................................................ 40
5.13   Daimler-Chrysler GaN FET. ................................................................................................ ................ 41
5.14   NEC 60 GHz CPW MMIC................................................................................................................... 42
5.15   A typical flip-chip MMIC structure by NEC........................................................................................ 43
5.16   Matsushita mm-wave system integration on a chip.............................................................................. 44
5.17   NTT's concept on 3D MMIC. ...................................................................................................... ........ 45
5.18   NTT U-band single-chip down converter............................................................................................. 45
5.19   NTT K-band Si 3D MMIC examples. .......................................................................................... ........ 46
5.20   PAE improvement with DC-DC converter by NEC............................................................................. 4 7
5.21   Hybrid adaptive predistortion method by Matsushita. ......................................................................... 48
5.22   NTT's multi sector monopole Yagi-Uda.............................................................................................. 49
5.23   NTT's rod type printed antenna. .......................................................................................... ................ 49

6.1    Phased array. ............................................................................................................... ......................... 54
6.2    Adaptive array. ........................................................................................................... .......................... 54

                                                                                                                                                           v


                                                          LIST OF TABLES
ES.1 A Comparison of Wireless Technologies and Networks in Europe, Japan and the United States ...... viii

2.1    Comparison of Research Activities ........................................................................................... ........... 13

4.1a   Propagation Models (1998-1999) ............................................................................................. ............ 29
4.1b   Channel Characterization (1997-1999)................................................................................................. 29
4.1c   Indoor-Outdoor Propagation (1995-1999)............................................................................................ 29
4 .2   Research Activities in the Channel Characterization and Propagation Models in Europe, Japan
       and the United States .......................................................................................................... .................. 30

5.1    Wireless Technology Assessment for Hardware ................................................................................. . 51

6.1    Technology Comparison....................................................................................................................... 58

vi

                                                                                                             vii


                                     EXECUTIVE SUMMARY

                    Anthony Ephremides and the Members of the WTEC Panel




INTRODUCTION

What follows is a summary discussion of the current state and trends in wireless communications. The
overview of this rapidly expanding and technologically diverse field is based on the discoveries of the
WTEC panelists during their site visits to leading companies and experts in Europe, Japan, and the United
States as well as the panelists' expertise in the various areas of wireless communications. Included in this
chapter are sections on the major drivers affecting wireless communications growth; a discussion of
bottlenecks, such as systems interoperability, that threaten the development of wireless connectivity; and,
finally, a sampling of technology highpoints, including the much-discussed "software radios."

The findings related in this study were made by the WTEC panelists listed in Appendix A. Table ES.1
(p. viii) contains a ratings chart that shows a general comparison of the three regions in the various
technologies essential to the field, summarizing this panel's findings.


U.S. COMPETITIVENESS

On the question of U.S. competitiveness, which of course ranks high in the interests of the sponsors, the
incomplete nature of the sampling, and U.S. and foreign reluctance to disclose fully, made a comparative
assessment of capabilities rather difficult. In addition, the corporate world of communications (wireless or
not) is especially globalized and international. It is increasingly difficult to identify national boundaries in
the activities of various companies. As an example, consider the case of Nokia, probably the most
successful manufacturer of cell phones at present, and one of the major players in the arena of wireless
communications. Most of Nokia's long-term research is conducted in Texas, and the overwhelming majority
of its stockholders are U.S. citizens. Yet, the corporate decisions are made in Helsinki.

In any event, the panel made a genuine effort to assess the comparative strengths and weaknesses in the
production of technologies that are crucial to wireless communications in the United States, in Europe, and
in Japan. The reader will find in several of the chapters that follow an evaluation based on numerical scores
that attempt to characterize the relative position of U.S. industry vis-a-vis that of European and Japanese
industry. Although the panel is making these disclaimers, it was able, in several cases, to provide such an
assessment. Specific assessments that the panel made are summarized in Table ES.1 (p. viii). And, indeed,
within each technical area there is some (but not much) variability. However, overall the state of
development of wireless communication technology in all three regions is very comparable. Thus, it is safe
to state that Europe, Japan, and the United States are engaged in a neck and neck race with increasingly
blurred boundaries among their efforts, goals, and achievements.

In the early development of the second generation cellular systems for cellular voice systems (which is only
one of the multiple facets of wireless), the European Global System for Mobile Communications (GSM)
system was an early winner, while Japan was a distant third in the race. Of course, the converging third
generation systems have brought all three regions close to each other. And, as stated earlier, there are many
other aspects of wireless communications in which the regions and industry compete.

                             WTEC Panel on Wireless Technologies and Information Networks
viii

A remarkable observation, however, is that, in a general sense, there is a difference in attitude toward
wireless technology development between the United States and Europe, on the one hand, and Japan, on the
other. The panel found that in the "Western" world the attitude is preponderantly market-driven, while in
Japan it seemed more technology-driven. As a result the panel found an increased readiness and imagination
in Japan to use the technology to develop applications and diverse usages, while in Europe there is a more
cautious and conservative attitude. In the United States there is a "happy medium" in that the commercial
world shares the caution of the Europeans, while the military establishment is pushing the frontiers to apply
every available bit of technology and to develop more technology.

                                              Table ES.1
       A Comparison of Wireless Technologies and Networks in Europe, Japan and the United States
                            Technology                  Europe Status     Japan Status      U.S. Status
        Hardware
        - mm wave circuits and systems                      ****             *****              **
        - Packaging/interconnect                             ***              ****            *****
        - CAD                                                ***               **             *****
        - SiGE/Si                                        ***** (Ger.)         ***              ****
        - III-V                                             ****             *****            *****
        - GaN                                                ***              ****             ****
        - Antennas                                           ***              ****             ***
        - Passive components                                ****             *****             ****
        - Amplifier technique                            **** (U.K.)          ****            *****
        - MEMS                                               **               ***              ****
        Channel Characterization and Propagation
        - Statistical/empirical                              ***              ***              ***
        - EM based deterministic                             **                 *              ***
        - Integrative models                                 **                 -               *
        - Microwave and millimeter wave                       *                **               **
        Coding, Modulation and Multiple Access               **               ***             *****
        - Multi-user detection theory                        **               ***             *****
        - Multi-user detection implementation                ***             *****             ***
        - Coding                                            *****             ***             *****
        - Multiple access                                   ****              ****             ****
        Software Radios
        - Software radio technologies                        ***              ***              ***
        - Energy efficient communications                    ***                *              ***
        - Integrated approaches                               *               ***               *

           * Number of asterixes corresponds to level/quality of activity; more is better

                                              Executive Summary                                                 ix

MAJOR DRIVERS OF THE GROWTH OF WIRELESS COMMUNICATIONS

Major factors in the growth of wireless communications include the following:
   personal communications
    -    the need of increasing numbers of people to communicate with each other anywhere, anytime
    -    wireless, multimedia delivery
   Internet services
    -    the expanding need of consumers to access a variety of Internet services without the constraining
         use of cable and other wire media
   military and security needs
    -    the strategic, tactical, and logistical needs to maintain communication in the conduct of operations
   specialized applications
    -    delivery of services such as telemedicine, replacement of cables at home, at the office, at the factory
         or elsewhere, and other untethered applications

MAJOR BOTTLENECKS IN THE DEVELOPMENT OF WIRELESS CONNECTIVITY

The Medium of Wireless Communication

There are two ways in which the medium raises serious technical challenges. The first one is the shortage of
usable bandwidth. The expanding need for high-rate multimedia applications squeezes the available
bandwidth in the frequencies at which propagation properties are favorable. Already most of the spectrum
up to the low GHz range is used up. Beyond that, i.e., at Ka-band and beyond, optical phenomena, such as
aerosol-induced dispersion, take hold and make communication at long ranges problematic. Yet, if the
ultimate goals of wireless connectivity are to be realized, the limitations at the higher bands (up to 100 GHz)
must be overcome.

The second limitation of the medium has to do with propagation and interference impairments. Multipath
propagation (and the resulting inter-symbol interference), Doppler, shadowing, variable dielectric properties,
etc. affect seriously signal strength and decoding ability. In addition, in the presence of multi-user
communication, interference from other users represents a major obstacle. Of course, already there are
technology directions that show promise toward overcoming these impairments (such as smart antennas,
elaborate MAC protocols, and multi-user detectors); however, much more is needed.

Portability of Equipment

For the ubiquitous use of wireless communication it is necessary that the user equipment (currently referred
to as the "handset" or the "palmtop") be extremely light, small, versatile, and above all, energy efficient.

Battery technology is only one of the means by which the longevity of portable devices can be assured.
Pulsed use of the batteries, appropriate circuitry and packaging, directional antennas, suitable modulation
and coding, and, most unexpectedly, intelligent network protocols can yield significant energy savings.
Furthermore, system integration and space-sensitive design of signal processing algorithms can reduce the
size (and weight) of the portable devices.

System Interoperability

One of the most disabling features in wireless communications is the simultaneous development of
incompatible standards. Even in the widespread application of cellular telephony, the current systems in the
United States, Europe, Japan, and the rest of the world are simply not compatible. Furthermore, if
connectivity to the Internet is to be realized, the interoperability of diverse systems, such as satellite

                       WTEC Panel on Wireless Technologies and Information Networks
x

networks, wireless access based systems, the public switched telephone network (PSTN), etc. must be
assured. Already progress has been made in the eagerly anticipated, so-called third-generation cellular
systems toward the celebrated goal of convergence. However, interoperability must extend beyond that.


THIRD GENERATION CELLULAR SYSTEMS

The panel found that the major current preoccupations of most companies involved "third-generation"
cellular systems. These systems defined most of the immediate concerns and shaped many future ones. Put
simply, the first analog voice cellular systems (exemplified by the U.S. AMPS system) would be the first
generation. The digital voice systems that followed (mainly the GSM in Europe and IS-136 and IS-95 in the
United States) would constitute the second generation while the term "third generation" would refer to
digital systems that superpose substantial data services. Of course the path to the third generation has been
evolutionary, and "fractional" systems between the second and third generations can be identified.

The long gestation period that has occurred between generations can be attributed in part to genuine
technical protocols, but primarily to economic and political difficulties that have to do with market share,
intellectual property disputes, and other competitive aspects of product development and service provision.

It does appear certain that within the next couple of years a quantum step in the advancement of wireless
communications will have occurred with the launching of third generation systems. But, then the question is
"what next?" The panel did ask that question and obtained a variety of answers. Some view as "fourth
generation" those systems that will be capable of delivering multimedia services at rates upward of 10 Mbps
to mobile users. Such systems will probably need to operate at the higher GHz regions of the spectrum
where there is ample bandwidth. Others are more skeptical, considering the whole issue of future generation
systems as obscure. However, many of these skeptics are involved in funded studies on the very issue of
fourth generation systems. Thus, undoubtedly, the next generation of wireless systems ranks high in
everyone's mind. It was interesting that some (especially in Japan) ventured a guess about what the fifth
generation wireless systems will look like. They presented a vision of unlimited bandwidth and of rates
exceeding 1 Gbps at the 60-90 GHz range for the ultimate realization of global wireless connectivity.


WIRELESS ARCHITECTURES

Many people wonder what wireless architectures, other than cellular and wireless LANs, are possible or
achievable in wireless networks. It has been known that at least in the United States, the military has shown
a keen interest in the so-called "ad-hoc" network architectures. The panel found that although Europe and
the United States showed rather limited interest in ad-hoc networks for commercial applications, there was
more interest in Japan. Some imaginative applications for the deployment of civilian ad-hoc networks that
involve large gatherings, stadium events, etc. were presented. A clear interest in ad-hoc networks of limited
scope for home entertainment was expressed everywhere. The first extremely successful such architecture,
which is intended for cable replacement at the office or at home, is the "Bluetooth" standard that has
experienced overwhelming acceptance in industry worldwide. However, "Bluetooth" is a modest ad-hoc
system. It involves only single-hop access to a "master" station and permits the participation of only up to
seven "slave" stations. Especially in home entertainment networks, relaying and multi-hop operation will be
required, since transmission power must be limited (because of a variety of regulatory and practical reasons)
and since room and floor partitions induce significant attenuation.


FINDINGS BY TECHNICAL AREA

Within each of the technical areas of the study, the panel reached specific conclusions about the issues that
researchers here and abroad agree require increased attention. These are reported in detail in the chapters of
the main body of the report. Here is a brief summary.

                                              Executive Summary                                               xi

Hardware

In the hardware area it is necessary to improve materials, components, and devices. In particular new
materials such as GaN and SiGe need to be exploited further. In addition, microelectromechanical systems
(MEMS) technology can offer advantages in building components. Extensions of the linear region for active
devices as well as improved performance of passive devices are necessary. It is also necessary to develop
broadband antennas of higher gain and lower cost phased arrays. In addition, exploitation of 3-D-oriented
packaging technologies offers significant promise.

As far as front-end architecture is concerned, the tradeoff between amplifier linearization and efficiency
must be optimized. Promise also appears in the development of multifunction/reconfigurable devices and
circuits (as well as antennas) in order to facilitate the operation of so-called software-defined radio (a notion
that has emerged as very prominent for the future of the field). Effort is needed to improve interconnects
and packaging, while use of MEMS technology for radio frequency (RF) components promises significant
gains.

Expansion of operation in the higher ends of the spectrum (10, 35, 60, 77, and 95 GHz) requires significant
breakthroughs in all aspects of hardware mentioned above. The use of computer-aided design (CAD) tools
for all-inclusive and interactive packaging that encompasses circuits, devices, and antennas, as well as
electromagnetic, thermal, and mechanical functions, is seen as necessary.

Smart Antennas

In the area of smart antennas, the major improvements needed to realize better coverage and higher data rates
are reduced cost and size (which requires improvements in both electronics and power consumption),
increased use of diversity, and better tracking of mobile users. Some of the research directions that hold
promise toward the achievement of these goals are the use of spatial-temporal signal processing algorithms,
better and more versatile definitions of standards, and, above all, interdisciplinary, vertically integrated
designs that incorporate hardware aspects, coding/modulation, access control, antenna directivity, switching,
connectivity control, multimedia techniques (such as adaptive compression), and overall systems
architecture. In fact, vertical integration emerged as another dominant notion for future wireless
communication systems.

Channel Characterization

In the area of channel characterization, it was confirmed that impairments on system performance inflicted
by the wireless medium continue to be a major bottleneck in the further development of wireless
communications. At a minimum, it is necessary to understand, measure, model, and characterize the
medium accurately before developing effective remedies.

As such, the key direction in channel modeling that the panel identified was the coupling of statistical with
computational (empirical) models. For analysts and designers, the embodiment of channel characteristics
into a few statistical parameters is very desirable and convenient as it simplifies the enormous task of overall
system design and evaluation. Such models usually do not provide sufficient accuracy, but, on the positive
side, they are not too dependent on specific environments.

On the other hand, computational models (such as ray tracing) are much more accurate but are very
dependent on specific environments and require prohibitive amounts of computation. The only avenue for
better channel characterizations requires imaginative coupling of these two methodologies. During its study
the WTEC panel did identify vestiges of such coupling already.

                        WTEC Panel on Wireless Technologies and Information Networks
xii

Link Layer

In the area of link-layer operation and design, which includes coding, modulation, and access control, there
are numerous ways in which wireless systems can benefit. After all, this is the most mature area in the
"systems" aspects of wireless communication, since it has been the cornerstone of classical point-to-point
transmission and has triggered the development of the immensely beneficial theories of communication and
information transfer.

Important directions for research with significant promise for the future include the following:
     improvement of decoding algorithms for turbo codes
     development of new coding/modulation schemes (which could yield large coding gains and permit
      higher data rates) to reduce the peak-to-mean envelope ratio
     development of coding/modulation techniques that are jointly designed with power amplifiers to extract
      benefits both in bandwidth and in energy savings
     development of demodulation/decoding techniques to simultaneously combat the near-far problem and
      do channel decoding in multi-rate code division multiple access (CDMA) systems
     better methods of channel estimation at high frequencies
     multiple-access techniques that are driven by different quality-of-service requirements in multi-rate
      systems
     analog decoding techniques for high-speed, low-rate systems
In addition, the panel saw overwhelming evidence of the need to couple these techniques with other aspects
of system design and technology that are used in the lower and higher layers of the networking architecture.
Thus, space-time coding for multiple antenna systems, hybrid error control methods, joint routing/link-layer
design, and energy efficiency are examples of integrated approaches that will be necessary for future high-
performance, ultra wide band systems.

In other words, again, the panel confirmed the need for vertical integration.

Switching/Networking

In the area of switching/networking, the panel observed the current incompatibility between the available
architectures and standards, and the overwhelming attention paid to third generation system design.
However, even through the third generation, the air interfaces, the signaling methods, and the handling of
roaming will remain dissimilar and incompatible. The third generation migration of GSM includes a
packetized transfer mode (referred to as "general packet radio service" or GPRS). However, the
incorporation of Internet Protocol (IP) in wireless networks is fraught with problems. Perhaps a sure way to
achieve a short term convergence between wireline and wireless networks is to rely on a connection-
oriented, circuit-switched architecture.

The key obstacles (and, hence, research areas) that make this aspect of wireless systems more uncertain and
less developed are the lack of understanding of how wireless access impacts the definition of a scalable
architecture, the lack of suitable protocols for interoperability between the core network and its wireless
extensions, and the difficulty of tracking mobility in real time (mobile IP is not a true mobility tracking
protocol).

Some notions that show promise for resolving these thorny issues involve the expansion of the "intelligent
network" (IN) concepts, the imaginative use of distributed databases and algorithms, and, perhaps, a multi-
tier architecture that will allow expansion of scale and will permit new services not yet developed or even
defined. Ultimately engineers will need to take a hard look at the possibility of end-to-end IP-based radio
systems.

                                              Executive Summary                                              xiii

Integrated Design

In the area of "holistic," or vertically integrated design, which emerged as a sufficiently dominant concept to
generate a separate section in the report, the major findings were, as already mentioned, that the development
of software-defined radios and energy/power management techniques were of foremost interest and
immediate concern.

Software radios are seen, in their early stages, as simply reconfigurable, multimode/multiband radios.
However, the extended concept of a software radio involves a wide front end and a totally software-
dependent baseband architecture that is capable of configuring the operation of the equipment to conform to
almost any desired protocol, algorithm, or processing structure. Although the realization of such a concept,
the most futuristic version of which anticipates downloading to the terminal the code that will define its
operation in real time, is still years if not decades away, its potential is formidable. Assuming questions of
cost can be resolved (through economics of scale) every mobile user can customize his own terminal to its
current environment. And, if questions of cost are not resolved, software radios can reside only at the base
station so that, with their superior "smartness" characteristics, they can adapt their communication to the
diverse and simple individual terminals on a one-to-one basis.

Energy savings can be realized in a variety of ways all along the stack of network protocols. From improved
battery technology and more efficient chip layouts, to better algorithms for signal processing and adaptive
antenna arrays, to improved coding/modulation techniques, to power management techniques in media
access control, numerous avenues are available to increase the longevity of untethered terminals and
equipment and to save operational and thermal costs at base stations. What is new is the realization that in
addition to these methods, network protocol design can have a significant impact on energy efficiency.
From pulsed operation of batteries (as for example in time division multiple access--TDMA--schemes) to
intelligent routing and multicasting, network protocols can create substantial energy savings. Furthermore,
in addition to transmission energy expenditures, there is energy consumed for processing and for simply
being "on." Thus, schedules of alternating between "sleep" and "on" modes (as in current paging systems),
joint design of compression and transmission schemes, etc., provide means for better overall energy
efficiency.


A SAMPLING OF TECHNOLOGY "HIGH-POINTS"

Since this study was performed as an "assessment" of current and future technology, and since its conduct
involved numerous site visits around the world, it is appropriate to summarize a few of the dominant points
of high technology that the WTEC panelists observed.

The widely espoused notion of "software radio" was a common theme throughout the site visits. The panel
was struck by the variety of levels at which this notion is conceived in different quarters. From the simplest
version of multi-mode/multi-band radios presented at Ericsson to the most imaginative versions encountered
elsewhere, it was clear that this will be the way of the future.

The integration of the antenna into the handset, seen at Nokia, was another harbinger of the direction of
future development.

The panelists even saw silver-plated sets that permit the installation of the antenna inside the terminal
through a thin-strip plastic window. A great deal of design effort was needed in shaping the antenna plate.

The availability of polymer batteries, displays, and electronics, seen at Philips, is another harbinger of things
to come. In addition to reducing weight and costs, these promise superior performance. The first integrated
channel characterization models, seen again at Philips, combine electromagnetics, statistics, and computation
to provide useful and reasonably accurate models of channel behavior.

                         WTEC Panel on Wireless Technologies and Information Networks
xiv

The packaging techniques at Matsushita were clearly indicative of superior achievement in the hardware
aspects of wireless communication.

The development of three-dimensional integration at Nippon Telegraph and Telephone (NTT) clearly points
the way toward size and weight reduction as well as improved performance.

At many sites (especially NTT) the panel was impressed by the effort being made toward reducing the cost
of phased arrays.

The SKYNET concept outlined at Yokosuka Research Park (YRP) in Japan is an impressive example of
imaginative wireless networking. It is based on a small number of large balloons, suspended in the
stratosphere and kept in place by solar-powered propellers, that permit the installation and support of
multiple antennas of various sizes. Through direct link connection to terrestrial sites and users, coverage
spans the entire region of Japanese territory. Thus, a constellation of satellite-like base stations creates an
adequate and relatively inexpensive infrastructure for wireless connectivity.

Study team members were also impressed by the actual deployment of a multi-user detector that utilizes
successive interference cancellation in CDMA systems. Although the theory of multi-user detection is quite
mature by now, concerns about cost and implementation have held back the incorporation of advanced
detectors in actual systems. At NTT DoCoMo, the developed system was at the stage of actual field trials
and tests.

Last, but not least, the panel found the advanced miniature multimedia terminals at NTT DoCoMo very
impressive and, also, forerunners of future development.


CONCLUSIONS

It is difficult to summarize the findings, observations, and impressions of such a vast study of such an
evolving discipline into a few concrete nuggets. Yet, it became clear to this panel that, after the dust had
settled, three major items stood out as the major areas of future technology that require significant additional
research. These include the following:
     the hardware integration that will realize the notion of a "system on a chip"
     the overwhelming need to exploit spatial diversity by means of smart antennas
     vertical integration of protocols in the design of software radio platforms
All three stood out as being dominant concerns of all visited companies and institutes, both in the United
States and abroad. It is also the unanimous and informed belief of the WTEC study team that resolving these
issues is necessary in order to realize the ambitious goal of global wireless connectivity.

                                                                                                           1




                                              CHAPTER 1


                                          INTRODUCTION

                                          Anthony Ephremides




INTRODUCTION

Rapid growth in wireless communications has recently stimulated numerous studies, workshops, reports, and
other activities. All aim at fostering broad appreciation and understanding of the field as well as at
formulating appropriate responses to trends in the development of related products and services. The WTEC
study was sponsored by an impressive number of agencies of the U.S. government, led by the National
Science Foundation. In fact, it was during a workshop sponsored by NSF in the summer of 1998 that a
recommendation emerged to sponsor such a study. The objective was to assess long-term trends in research
in the wireless communications area worldwide. A corollary objective was to use the findings to better
formulate research funding priorities for the U.S. agencies that will help promote and maintain the
competitiveness of the United States in this important technology area.

This introductory chapter describes the general parameters of the study and the approach that this panel took
in addressing the sponsors' charge.

The first realization was that the field of wireless communications has multiple facets. To some people it
conjures simply the image of cellular telephony and to others only propagation or fading phenomena. To the
members of the WTEC panel, it represents the full gamut of applications that encompass cellular telephony,
wireless LANs, Internet access, personal communications, telemedicine, other specialized applications, and,
last but not least, military communications (which include diverse uses with corresponding unique
requirements). It also encompasses, from the technology point of view, all the issues that traditionally
correspond to the seven layers of the open systems interconnection (OSI) architecture that has governed the
field of communications and networking in the last third of the 20th century.

This realization influenced the selection of the researchers and scientists who composed this panel, which
contained truly distinguished experts and recognized authorities at all levels of the OSI model.

The second realization was that the task was enormous in light of the resources of the study. There has been
such an intense and expansive growth in the field that almost every major company in the industrialized
world, as well as literally hundreds, if not thousands, of mushrooming small players, have entered the
technology and service arenas in this field. To fully access the status of wireless communications in the
world, the panel would have to engage in an impossible mission of visits and meetings, which, in addition to
being prohibitively expensive, would require a length of time that would render the findings obsolete by the
time the study concluded.

                                                1. Introduction
2

Thus, the panel decided to be selective. It concentrated on major companies and institutes and carefully
selected a representative set in the United States, Europe, and Japan.

The third realization was that applications are often ahead of theory and have been leading the development
of technology. As a result, the enormous financial stakes have created a very intense competitive
environment among the world's major players. In turn, this has diminished the willingness to share not only
current research and development plans but also longer-term plans.

Therefore, the panelists had to challenge their skills to infer the directions in which companies see the field
evolving.

A related realization was that the rapidity with which the wireless technology is used in a variety of new
applications has created an environment in which confusion (if not chaos) is common. Not only the general
public but also the technology developers themselves lack a firm, commonly held vision as to what is
important (both in terms of products as well as in terms of services).

Consequently, the panelists had to use their own expertise and understanding of the field to interpret and
complement the inputs they received.

Finally, the panel members realized that the community is paying a great deal of attention to the physical,
link, and media access control (MAC) layers in the field of wireless communications. This is the result of
previously dominant needs in military communications (that have led and predated the development of
commercial applications by many years) and in cellular communications.

Because of the emphasis on layering and because the panel members firmly believe (as do most of the
representatives of the sites it visited) that in wireless communications, hardware and networking aspects will
become increasingly important, if not dominant in the future, the panel decided to focus on all seven layers
of the OSI architecture as well as on antennas and equipment.


APPROACH

Based on the framework that emerged from these realizations during the early part of the study, the panel
developed a plan that included a schedule with specific benchmarks as well as a strategy for approaching the
subject. The goal was to maximize the efficiency of the data-gathering phase and to formulate a concept that
would be true to the overall framework.

Thus, the schedule of activities was organized as follows. It commenced with a kick-off meeting of the
panel (jointly with sponsors) in January 1999 in the Washington, DC area, during which the panel unfolded
its strategy. A technical workshop followed in the Washington, DC area on March 15, 1999, in which most
major U.S. companies active in the wireless communications area were invited to participate. The panel
chose to canvas U.S. industry opinion in this manner (rather than through individual visits) purely for
reasons of efficiency. Thirteen companies (listed elsewhere in the report) contributed inputs based on a
questionnaire that the panel developed and forwarded to them ahead of time. The collection of viewgraphs
from their presentations became (and still is) available from WTEC as a separate document.

Following that the panel took two weeklong trips to Europe and Japan, respectively, where it visited a total
of 24 companies and institutes. These visits took place in April, May, and early June 1999. The intensity of
the schedule necessitated splitting the group (consisting of panel members and of representatives of some of
the panel's sponsors) into subgroups. Thus, no single individual in the group enjoyed first-hand contact with
all of the visited sites. Shortly after the completion of these visits, a separate report for each site was
generated, authored by a pre-designated member of the group but in wide consultation with and inputs from
other panel members. These reports were sent to the visited sites for concurrence and, after revisions to

                                              Anthony Ephremides                                               3

account for hosts' comments, became available on the WTEC Web site. They are now included, after final
editing, as appendices C and D of this report.

At this point the panel needs to mention that representatives from some of the sponsoring agencies played a
very active role in participating in the conduct of this study. Through their membership in the travel group,
authorship of site-visit reports, and active deliberation with the panel, they provided valuable assistance in
shaping the outcome of the study.

Exactly because the site visit reports were generated as separate documents, the panelists felt that the
structure of the main analytical report should not follow the format of reporting findings from each site.
Rather, it was decided to structure the report on the basis of technical areas.

Thus, the specific elements found at a particular site, as they pertained to one technical area, would be fused
into the discussion of that area along with the appropriate elements found in other sites. In this way, the
panel members believe they have produced a more informed and informative report that will be more useful
to sponsors and to the community at large. In addition, under that structure, the findings would be consistent
with the principles of the framework outlined in the introduction.

In deciding what technical areas to choose so as to form a spanning skeleton for the entire field, it was
natural to follow the OSI layered architecture. Nevertheless, it is interesting to note that one of this panel's
major findings is that the traditional separate consideration of networking layers is less useful in the wireless
area. Indeed, the technical coupling among layers, always present even in nonwireless networks, is simply
too strong in wireless systems to be ignored. The convenience that separation into layers provides is in large
measure due to the fact that it ignores the interactions among layers. In wireless networks this convenience
is countered by the neglect of crucial interactions (between multiple access and routing or between link
control and compression, for example).

However, structuring the report along traditional layer lines does not contradict this finding. It simply
permits a clean organization of the report. In fact, relationships among the layers are duly noted and
reported as these arise. Thus, the chapters that follow in the main body of the report are centered,
respectively, on the following topics:
   hardware (i.e., materials, devices, circuits, amplifiers, antennas, and system integration that optimize
    efficiency in wireless communication)
   antennas and signal processing (i.e., the "systems" aspects of antennas, including spatio-temporal
    processing to combat fading and interference and to shape adaptively the antenna patterns)
   channel modeling (i.e., statistical and empirical models that predict propagation patterns and signal
    attenuation)
   modulation/coding/access (i.e., link-layer issues that govern quality of point-to-point transmission)
   networking/switching (i.e., architecture and higher-layer issues that affect quality of service system-
    wide)
   integrated/holistic design (i.e., a novel viewpoint that starts from the realization of inter-layer coupling
    and exploits the possibilities of software-defined radios, energy efficiency, and other issues that cut
    across layers)
After a brief gestation period following the site visits and the composition of the site-visit reports, the panel
held a final open workshop to disclose the preliminary findings of the study. This workshop was held in the
Washington, DC area in September 1999 and was attended by a large audience. The collection of
viewgraphs from the presentations by the panelists and the sponsors were posted on the WTEC Web site
shortly after the workshop (now superceded there by this final report). The present report constitutes the
final step in this study.

    1. Introduction
4

                                                                                                            5




                                              CHAPTER 2


                CODING, MODULATION, AND MULTIPLE-ACCESS

                                               Wayne Stark




OVERVIEW

The goal in wireless communication systems is to provide mobile, fully integrated, low cost, reliable,
seamless systems with the capability of providing voice, high speed data, and video with minimum latency
and long battery life. However, there are many obstacles and bottlenecks to achieving this in practice.
These bottlenecks include the following:
   limited spectrum
   limited energy
   multipath fading and propagation loss
   cost
   standardization processes
This chapter of the report focuses on coding, modulation, and multiple-access techniques for wireless
communications. To put the discussion in perspective, a short background on the development of wireless
communication systems, focusing mainly on cellular systems is provided. The following sections discuss
coding and modulation and various modulation techniques; present a comparative analysis of research and
development in Europe, Japan, and the United States; and, finally, make recommendations for further
research in wireless communications.


BACKGROUND

Cellular Systems

Wireless communications became a commercial success in the early 1980s with the introduction of cellular
communication systems in the United States, Japan, and Europe. All of these systems were based on
frequency division multiple-access whereby a user during a call was assigned a given frequency for
transmission to a base station (uplink) and a given frequency for reception from the base station (downlink).
The modulation technique adopted was frequency modulation (FM) for the voice signal. The bandwidth
assigned to each user was around 30 kHz (depending on the country). Frequency division multiple access
(FDMA) and FM modulation were well known techniques/technology available to system designers at the
time. It is interesting to note that a university professor in the early 1980s actually proposed code division
multiple-access (CDMA) as a technique for cellular communications, but AT&T/Bell Labs (pre-divestiture)
discredited it. At the time digital technology was not ready for a modulation technique requiring

                                  2. Coding, Modulation, and Multiple-Access
6

sophisticated processing algorithms. Nevertheless, the basic research component of this effort affected
future wireless communication systems.

The designers of cellular systems faced many challenges that were unique to mobile environments. These
challenges included time-varying multipath fading and interference from other users. The problem of
multipath fading was handled by simply increasing the amount of transmitted power. Most of the cell
phones were mounted in cars, handheld units were not available, and battery power was not the initial
driving force. Interference was minimized by not reusing a given frequency in an adjacent cell. Finally, the
application was purely voice communications.

In Europe, many different first generation systems operated in different frequency bands, and thus roaming
between countries was not possible with a single cell phone. This lack of interoperability in Europe was one
of the key drivers towards developing a second generation system in Europe. In the United States, the
increased use of cell phones in the mid-1980s led to a shortage of capacity in major markets (Los Angeles,
New York, Chicago). In order to achieve higher capacity (users/cell/Hz) second generation systems began
development in the mid-late 1980s. Second generation systems (in the United States, Europe, and Japan) are
all based on digital transmission techniques whereby the voice signal is encoded into a sequence of bits. The
voice-coded data is then encoded for error correction and modulated using digital modulation techniques.
Going to a digital modulation technique has several advantages, including the spectral efficiency of digital
modulation, the capability of combining speech and data services, and the improved security of digital
techniques. The first proposal for second generation systems in the United States was based on time-division
multiple-access (TDMA) whereby each 30 kHz of bandwidth was slotted in time so that three users could
use the same spectrum. This was possible because of the compression algorithms applied to speech
waveforms. In these systems error correction was introduced to mitigate the effect of multipath fading.
Interference is not a predominant issue in this design as different users use either different frequency or time
slots or nonadjacent cells. Like first generation systems, essentially the only application for second
generation systems (both cellular and personal communication systems (PCS) that use the 1900 MHz
frequency band) is voice, although some low speed data communication capabilities are also possible.

It is interesting to note that the modulation technique chosen in Europe (Gaussian minimum shift-keying) for
second generation systems is a constant envelope technique while the modulation technique chosen in the
United States and Japan is /4 differential phase shift keying (DPSK) with raised cosine filtering, which is a
nonconstant envelope technique. Constant envelope techniques ensure that the envelope of the transmitted
signal is a constant. This fact allows the power amplifier used by the mobile system to operate near
saturation without distorting the signal. The most energy efficient operation of an amplifier is near
saturation as this is when the power added efficiency is largest. The disadvantage of constant envelope
modulation techniques is that their bandwidth efficiency is small relative to modulation techniques that have
fluctuating envelopes. On the other hand nonconstant envelope modulation techniques need very linear
amplification in order to preserve the signal shape (no distortion). Nonlinearities applied to a nonconstant
envelope technique create both adjacent channel power and in-band intermodulation distortion. The adjacent
channel power essentially widens the bandwidth occupancy of the signal while the in-band intermodulation
distortion acts like additional noise in the system. No distortion is incurred when linear amplification is used
with nonconstant envelope modulation techniques. However, linear amplification is possible mainly by
operating the amplifier with a small input signal (large backoff) where the energy efficiency of the amplifier
is smallest. This characteristic of nonlinear amplifiers makes large power efficiency and bandwidth
efficiency hard to achieve simultaneously.

In the late 1980s Qualcomm made a proposal to use direct-sequence spread-spectrum multiple-access (also
called code division multiple-access) for cellular systems. Qualcomm's initial claims of significant (more
than 10 times) increase of capacity of cellular systems captured the attention of service providers. This effort
developed into a later second generation standard known as IS-95. The increase in capacity, it was claimed,
was due to exploitation of the voice activity factor, Rake reception, which allowed exploitation of the
multipath fading and frequency reuse of 1 (every cell uses all frequencies), which allowed more efficient use

                                                Wayne Stark                                                 7

of the frequency spectrum over a geographical area. In addition, multiple users spreading their signals over a
wide bandwidth with user unique codes allowed for multiple users using the same spectrum at the same time.
The IS-95 system uses 1.25 MHz of spectrum. The IS-95 system first became available commercially
around 1995.

A significant event for wireless communication systems occurred in the mid-1990s when the Federal
Communication Commission (FCC) decided to auction off spectra in the 1.9 GHz band. This opened up a
pair 60 MHz frequency bands between the 1850-1910 and 1930-1990 MHz spectra for use by those with
winning bids in the auction. This band was called the personal communication system (PCS) band, and
systems operating in this band are called PCS systems. The modulation and coding techniques that were
chosen for these systems were virtually all-cellular type systems except they were shifted up in frequency.
The operating characteristics (coding, modulation, and multiple-access) were identical. Nevertheless this
provided additional capacity for wireless communications and allowed for increased competition.

The overall goal of first and second generation systems is primarily voice communications. The innovations
between first and second generations were mainly in going to digital modulation techniques and the use of
error control coding. Third generation systems are now being designed and implemented to handle not only
voice but high speed (from 384 kbps to 2 Mbps) data, although no one really knows what the market for
these services will bear.

Other Wireless Systems

Cellular communication systems are clearly the most widely used wireless communication systems.
However, other systems have different characteristics that deserve mentioning. To begin with, many
military communication systems need to operate in a very different type of environment. First, in a military
communication system, there may not be the possibility of dividing a region into cells and deploying a base
station in each cell. Military systems tend to be highly mobile and may possibly operate in unfriendly
environments where the cellular type of deployment is not possible. Military systems must also face the
possibility of hostile interference (jamming). One of the consequences of not having base stations is that
relaying messages is required. In other words, multihop communications over multiple wireless links is
necessary. This creates a whole new class of communication problems and constraints.

Another wireless communication system of interest is a wireless local area network (WLAN), whereby a
wireless link replaces the wired LAN. Currently such systems tend to operate in the Industrial-Scientific-
Medical (ISM) band (902-928 MHz, 2400-2483 MHz, 5725-5780 MHz). This band is available for
unlicensed use (in the United States) provided either the power levels are small enough or spread-spectrum
modulation techniques are employed with larger transmitted power. The 2.4 GHz band is available world-
wide while the 900 MHz band is not available is some parts of the world (e.g., Europe).

Another wireless system gaining significant attention is a cable replacement wireless system called
Bluetooth. This is being developed by a consortium of communications and computer companies (e.g.,
Ericsson, Nokia, IBM, Intel, Motorola). The objective of a Bluetooth system is to replace the cables
connecting different components in a computer system with wireless links. Because it is a cable replacement
the objective is for a very low cost, low range system. It is also viewed as a means for connecting a mobile
computer with a cell phone in a wireless manner such that communication between the mobile computer and
a hidden (e.g., in the briefcase) cell phone can be used to connect to the Internet. It can also connect a
headset to a cell phone without wires. The range is about 10 meters with 0 dBm (1 milliwatt) transmitted
power, but can be increased to 100 meters with larger power. Bluetooth uses the 2.4 GHz ISM band with
frequency-hopped spread-spectrum. The maximum data rate is 721 kbps. It handles up to 8 devices in a so-
called "pico-net" and can have up to 10 pico-nets operating in a coverage area. The networks created with
Bluetooth are ad-hoc networks implying multiple-hops per end-to-end connection.

A competing system is HomeRF. HomeRF is geared more towards higher data rates and higher transmitted
power. As with Bluetooth, HomeRF is a frequency-hopping system operating in the 2.4 GHz band.

                                                                  2. Coding, Modulation, and Multiple-Access
8

Products with data rates in the range of 2 Mbps with operating distances on the order of 150 feet are
possible.

The development of a variety of communication systems is shown in Fig. 2.1 as a function of data rates and
user mobility/cell sizes. This figure illustrates the fact that higher data rates are possible at lower mobilities
or decreased cell size. This is due to two considerations. The first (and main) consideration is that at smaller
distances the propagation loss is less and thus for a given power level, higher values of E b/N0, the received
signal-to-noise ratio, are possible. Another effect is that at high mobilities the channel is harder to estimate
and thus proper demodulation/decoding becomes more difficult. This is compensated for, to a certain extent,
by the fact that generally error control coding works better (for a fixed block length) when the channel is
memory-less (independent fading on different symbols).
                                 Vehicular




                                                                               IMT-2000,        4-th
                                                                                3G Cellular, Generation
             Mobility/Cellsize




                                                                                  W-CDMA      Cellular
                                                       Cellular
                                              Paging
                                 Pedestrian




                                                                                      High Speed
                                                                                         Data
                                                                                       (MMAC)             Ultra High
                                 Indoor




                                                                                                          Speed LAN
                                                                                                           60 GHz?
                                                                                    Home RF
                                                                                    Bluetooth


                                                       10k              100k                        10M          100M
                                                                                      1M
                                                                                  Data Rate (bps)
       Fig. 2.1. The development of a variety of communication systems is shown as a function of
                 data rates and user mobility/cell sizes.


CODING AND MODULATION

Coding and modulation provide the means of mapping information into waveforms such that the receiver
(with an appropriate demodulator and decoder) can recover the information in a reliable manner. The
simplest model for a communication system is that of an additive white Gaussian noise (AWGN) system. In
this model a user transmits information by sending one of M possible waveforms in a given time, period T,
with a given amount of energy. The rate of communication, R, in bits per second is log 2(M)/T. The signal
occupies a given bandwidth W Hz. The normalized rate of communications is R/W measured in
bits/second/Hz. The received signal is the sum of the transmitted signal and white Gaussian noise (noise
occupying all frequencies). The optimum receiver for deciding which of the M signals was transmitted
filters the received waveform to remove as much noise as possible while retaining as much signal as
possible. For a fixed amount of energy, the more waveforms (the larger M) the harder it is for the receiver to
distinguish which waveform was transmitted. There is a fundamental tradeoff between the energy efficiency
of a communication system and the bandwidth efficiency. This fundamental tradeoff is shown in Fig. 2.2.
In this figure the possible normalized rate of transmission (measured in bits per second per Hz) is shown as a
function of the received signal-to-noise ratio Eb/N0 for arbitrarily reliable communication. Here, Eb is the
amount of energy received per information bit while N0 is the power spectral density of the noise. The
curves labeled AWGN place no restrictions on the type of transmitted waveform except that the average
energy must be constrained so that the received signal energy per bit is E b. The curve labeled BPSK restricts

                                                                     Wayne Stark                                  9

the modulation (but not the coding) to binary phase shift keying. The curve labeled QPSK is for quaternary
phase shift keying and the 8-PSK curve is for 8-ary phase shift keying. Clearly at low rates and low E b/N0
there is virtually no loss in using QPSK modulation with the best coding compared to the best modulation
and coding. Also shown in the figure is what can be achieved with certain coding schemes. While these
curves show the best possible transmission rate for a given energy, no restrictions are placed on the amount
of delay incurred and on the complexity of implementation. It has been the goal of communication
researchers and engineers to achieve performance close to the fundamental limits with small complexity and
delay.
                                      30
                                                   AWGN                       8-PSK

                                      25
                      Rate (bps/Hz)




                                      20
                                                                              QPSK


                                      15


                                                                              BPSK
                                      10

                                                                       RS(255,223)

                                                                  Conv(7)
                                      05
                                                   Turbo(65536,18)

                                       0
                                           2   0       2      4              8        10   12   14           18
                                                                       6                               16

                                                                                                Eb N0 (dB)
                 Fig. 2.2. Possible transmission rates versus signal-to-noise ratios for an
                           additive white Gaussian noise channel.

For a wireless communications system, the AWGN model is much too simplistic. In a wireless
communication system the transmitted signal typically propagates over several distinct paths before reaching
the receiving antenna. Depending on the relative phases of the received signal the multiple signals could
interfere in a destructive manner or in a constructive manner. The result of the multiple paths is that the
received signal amplitude is sometimes attenuated severely when the signals from different paths cancel
destructively, while sometimes the signal amplitude becomes relatively large because of constructive
interference. The nature of the interference is, in general, time varying and frequency dependent. This is
generally called time and frequency selective fading. A typical time response for a multipath fading channel
is shown in Fig. 2.3.

The received signal varies more quickly as the vehicle speed increases. In the original analog cellular
systems in order to compensate for the multipath fading, the transmitter increased or decreased the amount of
transmitted power. As with the additive white Gaussian noise channel, there are fundamental limits on the
rate of transmission for a given average received energy-to-noise ratio (Eb/N0). In the simplest model the
received signal energy is modeled as a Rayleigh distributed random variable, independent from symbol to
symbol. With this assumption the transmissions rates possible, as a function of the average received signal-
to-noise ratio, are shown in Fig. 2.4. The gray curves represent the performance possible in an additive
white Gaussian noise channel while the dark curves represent the performance with Rayleigh fading. The
assumption in this figure is that the channel bandwidth is very narrow and so the result of fading is to only
change the amplitude of the signal and not distort the signal in any other way. This is clearly not valid for
many communication systems (especially wide bandwidth systems like direct-sequence CDMA).

                                                                         2. Coding, Modulation, and Multiple-Access
10

                                                            10


                                                             5


                                                             0


                                   Fading Amplitude (dB)    -5


                                                           -10


                                                           -15


                                                           -20


                                                           -25


                                                           -30
                                                                 0       0.1        0.2       0.3       0.4       0.5      0.6        0.7        0.8
                                                                                                         t
            Fig. 2.3. Received signal strength as a function of time for vehicle velocity 10 mph.

                                                            30
                                                                             AWGN                             8-PSK

                                                            25
                   Rate (bps/Hz)




                                                            20
                                                                                                         QPSK


                                                            15



                                                            10
                                                                                          BPSK


                                                                                                        Conv(5)
                                                            05


                                                                                    Turbo(50000,5000,420)
                                                             0
                                                                     2   0      2         4         6         8       10   12    14         16         18


                                                                                                                                 Eb N0 (dB)

      Fig. 2.4. Possible transmission rates versus signal-to-noise ratios for a Rayleigh fading channel.

A key observation from this figure is that there is not a significant loss in performance between what is
possible in an additive white Gaussian noise channel and what is possible in a fading channel. For example
for transmission rates less than 1/2 bps/Hz the loss in performance due to fading is less than 2 dB with the
optimal coding and with BPSK modulation. However, for BPSK alone (without coding), the loss in
performance compared to white Gaussian noise channels is on the order of 40 dB when the desired error
probability is 10-5. This is a huge loss and is due to the fluctuations of the signal amplitude. Basically the
fading process sometimes attenuates the signal so that the conditional error probability is close to 1/2.
Sometimes the fading accentuates the signal so that the conditional error probability is virtually zero. The
average error probability then is dominated by the probability that the fading level is small. This can be
overcome with one or a combination of several techniques. Antenna arrays whereby the received signal at
different antennas fades independently is one such technique (discussed in Chapter 6). Another technique is
time diversity through coding. In the simplest realization of this, information is transmitted multiple times

                                                 Wayne Stark                                                 11

spaced far enough apart (in time) so that the fading is independent. At the receiver the signals are combined
appropriately. In this manner the probability of error is dominated by the probability that the fading
processes attenuate all the transmissions of a single bit. The probability of this event is much smaller than
the probability that during a single time instant the fading process will cause significant attenuation. This is
essentially a simple form of coding. Another simple form of coding is through frequency diversity. In this
case the same information is transmitted over several different frequencies simultaneously. Because the
channel is frequency selective not all the frequencies fade simultaneously. In this way diversity is achieved
as long as the frequencies used are sufficiently separated (separation larger than the coherence bandwidth of
the channel).

The conclusion from the previous discussion is that, for a fading channel, coding and/or diversity techniques
are essential in providing performance close to optimal. As before, there are underlying assumptions that the
delay is not a major constraint. In the time diversity system, identical data are transmitted but spread out in
time. In order to achieve good performance the time separation needs to be sufficiently large so that the
fading is nearly independent. In the frequency diversity case, a similar argument is made with the
frequencies used. So a large time-bandwidth-space product is needed in order to achieve reasonable
performance. In a wireless system, error control, coding and modulation are used to protect the data not only
against the effects of fading but interference as well. Interference will be discussed in the multiple access
section.

In 1993 a new coding technique (known as turbo codes) was shown to have exceptional performance in an
additive white Gaussian noise environment, coming within 0.7 dB of the fundamental limit for a Gaussian
channel with a code with block length on the order of 65,000 bits (Berrou et al. 1993). Since that discovery
was made, considerable effort has begun on investigating these codes on other channels and with different
block lengths. For an ideal Rayleigh fading channel (independent fades for each symbol) turbo codes with
block length 50,000 approach within about 1.5 dB of the fundamental limit when the channel is known
perfectly. For the white Gaussian noise channel, low density parity check codes are within 0.01 dB of the
fundamental limit when the block length is very large. When the block length is shorter (as required by
delay constraints in many applications) then the performance of turbo codes deteriorates to the point that
traditional convolutional codes perform better. Third generation cellular systems will employ turbo codes
for relatively long (e.g., larger than 300 bits) block length messages.

Many different modulation schemes are used in current wireless systems, among these binary phase shift
keying (BPSK), Gaussian-filtered minimum shift keying (GMSK), /4 DPSK, offset quadrature phase shift
keying (OQPSK), and orthogonal frequency division multiplexing (OFDM) (multicarrier). There are a
couple key issues when designing a modulation technique. One of these issues is whether the technique uses
a constant envelope or a nonconstant envelope. Constant envelope modulation techniques can cope with
amplifier nonlinearities but have larger bandwidth than nonconstant envelope modulation techniques. On
the other hand, a power amplifier is most energy efficient when operating in the nonlinear region.
Nonconstant envelope techniques have smaller bandwidth but need a very linear amplifier to avoid
generating both in-band distortion and adjacent channel power. The goal is to have bandwidth efficiency
and power efficiency simultaneously. However, with current amplifier designs there is a tradeoff between
these two conflicting objectives.

Another key issue when dealing with modulation is intersymbol interference. A wireless channel generally
has multipath fading, which causes intersymbol interference if the data symbol duration is the same
magnitude or smaller than the delay spread of the channel. As the data rate increases, the amount of (number
of symbols affected by) intersymbol interference increases. This generally increases the complexity of the
receiver. One method to avoid this is to transmit information on many different carrier frequencies
simultaneously. This makes the symbol duration on each carrier much longer (by a factor equal to the
number of carriers) and thus decreases the amount of intersymbol interference. However, multicarrier
modulation techniques have a particularly high fluctuation of the signal envelope; and thus to avoid

                                  2. Coding, Modulation, and Multiple-Access
12

generating unwanted signals (in-band or adjacent channel) an amplifier with high backoff (low input drive
level) is required, which means that the energy efficiency will be very small.

Another approach to dealing with multipath fading is to use wide bandwidth modulation techniques,
generally referred to as spread-spectrum techniques. Because of the frequency and time selective nature of
the wireless channel, a narrowband signal might experience a deep fade if the phases from multiple paths
add up in a destructive manner at the receiver. These deep fades generally need extra protection to prevent
errors by either increasing the power or adding additional redundancy for error control coding. On the other
hand, if the signal has a wide bandwidth (relative to the inverse of the delay spread) then not all the
frequencies in a given band will simultaneously be in a deep fade. As such the signal from the part of the
spectrum that is not faded can still be recovered. One realization of this idea is that of a direct-sequence
system that uses a Rake receiver to "collect" the energy from several paths (at different delays). The
probability of all of the paths fading simultaneously becomes much smaller than the probability of one of the
paths fading. Because of this the performance is significantly improved compared to a narrow-band system.
However, the performance is limited by the bandwidth available.


MULTIPLE-ACCESS TECHNIQUES

Cellular systems divide a geographic region into cells where a mobile unit in each cell communicates with a
base station. The goal in the design of cellular systems is to be able to handle as many calls as possible (this
is called capacity in cellular terminology) in a given bandwidth with some reliability. There are several
different ways to allow access to the channel. These include the following.
    frequency division multiple-access (FDMA)
    time division multiple-access (TDMA)
    time/frequency multiple-access
    random access
    code division multiple-access (CDMA)
     -   frequency-hop CDMA
     -   direct-sequence CDMA
     -   multi-carrier CDMA (FH or DS)
As mentioned earlier, FDMA was the initial multiple-access technique for cellular systems. In this technique
a user is assigned a pair of frequencies when placing or receiving a call. One frequency is used for downlink
(base station to mobile) and one pair for uplink (mobile to base). This is called frequency division
duplexing. That frequency pair is not used in the same cell or adjacent cells during the call. Even though the
user may not be talking, the spectrum cannot be reassigned as long as a call is in place. Two second
generation cellular systems (IS-54, GSM) use time/frequency multiple-access whereby the available
spectrum is divided into frequency slots (e.g., 30 kHz bands) but then each frequency slot is divided into
time slots. Each user is then given a pair of frequencies (uplink and downlink) and a time slot during a
frame. Different users can use the same frequency in the same cell except that they must transmit at different
times. This technique is also being used in third generation wireless systems (e.g., EDGE).

Code division multiple-access techniques allow many users to simultaneously access a given frequency
allocation. User separation at the receiver is possible because each user spreads the modulated waveform
over a wide bandwidth using unique spreading codes. There are two basic types of CDMA. Direct-
sequence CDMA (DS-CDMA) spreads the signal directly by multiplying the data waveform with a user-
unique high bandwidth pseudo-noise binary sequence. The resulting signal is then mixed up to a carrier
frequency and transmitted. The receiver mixes down to baseband and then re-multiplies with the binary
{1} pseudo-noise sequence. This effectively (assuming perfect synchronization) removes the pseudo-noise
signal and what remains (of the desired signal) is just the transmitted data waveform. After removing the

                                                  Wayne Stark                                               13

pseudo-noise signal, a filter with bandwidth proportional to the data rate is applied to the signal. Because
other users do not use completely orthogonal spreading codes, there is residual multiple-access interference
present at the filter output.

This multiple-access interference can present a significant problem if the power level of the desired signal is
significantly lower (due to distance) than the power level of the interfering user. This is called the near-far
problem. Over the last 15 years there has been considerable theoretical research on solutions to the near-far
problem beginning with the derivation of the optimal multiuser receiver and now with many companies (e.g.,
Fujitsu, NTT DoCoMo, NEC) building suboptimal reduced complexity multiuser receivers. The approach
being considered by companies is either successive interference cancellation or parallel interference
cancellation. One advantage of these techniques is that they generally do not require spreading codes with
period equal to the bit duration. Another advantage is that they do not require significant complexity
(compared to a minimum mean square error--MMSE--detector or a decorrelating detector). These
interference cancellation detectors can also easily be improved by cascading several stages together.

As a typical example, Fujitsu has a multistage parallel interference canceler with full parallel structure that
allows for short processing delay. Accurate channel estimation is possible using pilot and data symbols.
Soft decision information is passed between stages, which improves the performance. Fujitsu's system uses
1-2 stages giving fairly low complexity. Fujitsu claims that the number of users per cell increases by about a
factor of 2 (100%) compared to conventional receivers and 1.3 times if intercell interference is considered.


COMPARATIVE ANALYSIS

It is useful but difficult to compare the research being done in different countries in the area of wireless
communications. First, the panel visited only a handful of companies in each region. Second, these were
generally the larger companies with more visibility. Third, proprietary research was not included as part of
any discussion. Nevertheless, based on what the members of the panel saw, the WTEC panel has attempted
to compare the research activities in various regions, as summarized in Table 2.1 below.

                                                  Table 2.1
                                       Comparison of Research Activities
                               Research Area                U.S.      Europe      Japan
                     Multiuser Detection Theory             *****       **         ***
                     Multiuser Detection Implementation      ***        ***       *****
                     Coding Theory                          *****      *****       ***
                     Coding Practice                        ****       ****       ****
                     Multiple-Access                        ****       ****       ****


CONCLUSIONS

Throughout this study, and based partially on interactions with selected U.S., European, and Japanese
companies, it is recognized that there is substantial need for systems research for future wireless
applications. The following research areas are either emerging or evolving and are considered important for
future health of wireless communication systems:
   new decoding algorithms for turbo codes for wireless channels
   new coding/modulation techniques for reducing the peak-to-mean envelope ratio, maximizing the data
    rate and providing large coding gain
   new approaches to jointly designing modulation techniques, and power amplifiers to simultaneously
    obtain high power added efficiency along with bandwidth efficiency

                                   2. Coding, Modulation, and Multiple-Access
14

    new demodulation/decoding techniques to simultaneously combat the near-far problem and do channel
     decoding in multi-rate DS-CDMA systems
    communication problems unique to high frequency systems (e.g., channel estimation)
    joint channel estimation and decoding/demodulation algorithms
    multiple-access techniques for multi-rate systems with variable quality of service requirements
    space-time coding for systems with multiple antennas
    analog decoding techniques for high speed, low power systems
    ultra wideband systems and hardware design
    research in methodologies for an integrated approach to wireless communications (device layer: e.g.,
     power and low noise amplifiers, mixers, filters; physical layer: coding, modulation; medium access
     layer: CDMA/FDMA/TDMA; data link layer: hybrid ARQ; network layer: routing protocols)

REFERENCES

Berrou, C., A. Glavieux, and P. Thitimajshima. 1993. "Near shannon limit error-correcting coding and decoding: turbo-
    codes." Proceedings of the 1993 International Conference on Communications 10641069.

                                                                                                             15




                                               CHAPTER 3


            SWITCHING AND ROUTING IN WIRELESS NETWORKING

                                          Raymond L. Pickholtz




PREFACE

In the course of WTEC site visits to organizations in Europe and Japan, very little attention was given to the
subject of switching and routing in wireless communication networks. The draft site reports of October
1999 had only two short references to the subject. This is not for want of questions, but rather that the sites
the panel visited. The researchers were focused on RF circuitry, modulation and (some) coding, software
issues, and the design of the user terminal. There is perhaps a feeling, with exceptions, of course, that the
core network is there anyway, so let that be a given. This report therefore, incorporates ideas expressed by a
limited number of individuals who had opinions on this issue. In the interest of making this report somewhat
more complete than simply a recitation of a small portion of the site visits, it is supplemented by a perusal of
the literature and by off-line conversations with others knowledgeable in the subject.


INTRODUCTION

Convergence

There is a consensus that wireless data and multimedia traffic will overtake voice traffic in a relatively short
span of time (perhaps as early as 2002). Cellular technologies are developing at a very rapid pace. As
outlined elsewhere in this summary report of the panelists, new techniques have been developed for the third
generation (3G) ranging from radio frequency components, antenna technology, signal processing, source
and channel coding, interference reduction, and the various methods for improving spectral efficiency.
Virtually all of these novelties and inventions are directed at improving the air interface, i.e., what happens
between a mobile user and a base station at radio frequency transmission, reception and subsequent signal
processing. However, for the most part, the large-scale (core) network that ultimately connects a wireless
user to other remote users (wireless or otherwise) is still based on the traditional circuit switched network
designed to carry telephonic voice traffic. One of the major dilemmas facing network designers is how to
make a convergence among four apparently different service objective as shown in Fig. 3.1.

Figure 3.1 shows on the lower left the historic basis of communication networks, i.e., (voice) telephony.
Traditionally, and for the most part, using a wired network. Furthermore, and perhaps more importantly, the
talking path and end to end connection is circuit switched with dedicated resources being allocated (trunk
lines, switching, monitoring subroutines, etc.) exclusively for each call. While call set up has progressed to a
(logically) separate packet switched data network (SS7), the concepts remain rooted in the dominance of
fixed location telephony. The wired network started to be used for the transmission and reception of non-
voice data traffic over 30 years ago using modems, and more recently, with ISDN, ADSL, cable systems and

                              3. Switching and Routing in Wireless Networking
16

even fixed point satellite access. These, and the older transmission means, are now providing multimedia
and Internet traffic to homes and offices. This service development is the third bubble on the lower right of
Fig. 3.1. Finally, the upper left bubble is wireless technology that allows tetherless and roaming access to
users.



                                 Wired
                                                                         Wireless



                                                    Fourth
                                                   Generation


                                                                          Multimedia
                                                                           Internet
                              Telephony


                                      Fig. 3.1. Four way convergence.

For the most part, as stated earlier, wireless services have been, until very recently, mostly telephony and
short message services (paging, etc.). The core mechanism for switching and routing of wireless services
remains dependent on the telephony circuit switching even for the third generation (3G) of wireless network.
It is a prime objective of many organizations in Europe, North America, Asia, and elsewhere to converge all
these and possibly future service on a common platform. In this report, we review some of the ideas and
plans to accomplish that. A fairly conservative approach currently being deployed is shown in Fig. 3.2.


                                                      RA


                                              BS
                                                                                             Gateway
                                                                          Serving
                                                                BSC/CS     node




                      Pico
                      Micro                   MSC/Gateway                       IP Network

                     Macro
                    Satellite
                    Coverage
                              Fig. 3.2. Vision of a seamless wireless network.

The objectives of such a plan is to "marry" the circuit switched cellular wireless systems shown on top, with
the IP (Packet switched) Internet network via gateways. Such a solution could include first and second
generation wireless or other legacy air interfaces, but it is wholly insufficient for the kind of features
required for mixed media and broadband services. These features include, but are not limited to the
following:

                                                   Raymond L. Pickholtz                                    17

   on demand bandwidth for real time traffic
   scalable architecture
   differentiated services and, if required, differentiated pricing
   multiple aggregated radio links
   transport to/from heterogeneous mobile end-users
   flexible resource management
   full roaming capability
   World Wide Web (WWW) and other Internet services
   virtual networks

Roaming capability is provided for in 2nd generation systems by transferring the database relating to a
roaming user from a home location register (HLR) to a visitor location register (VLR) over a signaling
network. An illustration of this for GSM is shown in Fig. 3.3 where the standard B, C, D, and G interfaces
are used to link the VLR to the HLR and the Mobile (circuit) Switching Centers (MSC) to each other.


                                                                                    )

                                                                                            (,5
                                         %6&                 06&
                                                                   %                    &
                                 $ELV
                       8P
                                                                                    '       +/5
                                                                       9/5

                       06
                                                         *



                                                   9/5
                                                                             ISDN
                                               %
                                        06&                              PSTN




                       Fig. 3.3. Second generation (GSM/CDMA) network architecture.

The Equipment Identification Register (EIR) is used to verify and identify the individual mobile user
equipment. CDMA also uses a similar kind of architecture with the main differences being the air interface
modulation and the interface between the Base Station (BS) and the Base Station Controller (BSC), Abis.
As shown in Fig. 3.3 there are also provisions for the MSC to connect directly to the Public Switched
Telephone Network (PSTN) via digital lines or to use ISDN.


BROADBAND AND INTERNET ACCESS

At most locations the panel visited in Europe and Japan, it saw a need to design an architecture for wireless
networks that was capable of providing much higher data rates than exist in second generation cellular
systems, regardless of the details of the air interface standards. Furthermore, the need exists for multimedia
delivery to a small (handheld or laptop) terminal. At the present time, the focus is in supplying World Wide
Web (WWW) and general Internet services. While there is limited potential for doing this using the PSTN,
which the second generation relies on, such an approach is likely to prove inadequate and both the air
interface and the core network switching and routing will need to change to accomplish the task. There are a
number of competing approaches. The two most prominent are (1) wireless ATM and (2) some form of
packet radio. Both of these ultimately envision packet or cell transmission end to end. That is, including the

                              3. Switching and Routing in Wireless Networking
18

air interface, but also fundamentally changing the routing and switching in the core network away from
traditional voice oriented circuit switching. Among the many variations of these proposals, the one that
stands out because it is currently implemented and shows promise for smooth evolution to the full
convergence is General Packet Radio Service (GPRS).

GPRS

GPRS is an outgrowth of GSM/TDMA in Europe. Its basic architecture is the transmission of packets and is
designed to support IP while minimizing hardware modifications of existing network elements. The packet
format and its derivation from the GSM eight time slot air interface are show in Fig. 3.4 using slot number 4.




                                       Fig. 3.4. GPRS packet format.

This can provide about 18 kbps of true throughput (overhead excluded) per slot. Several slots can be used to
increase this rate. The layered architecture for GPS is shown on figures 3.5a, 3.5b, and 3.5c. Here is
illustrated the interface, Um, between the mobile transceiver and the Base Station Controller (BSC).

                                      Raymond L. Pickholtz                                             19



                                                 S NDC                    S ND C
                                                    P                        P
                                                 LLC                       LL C


                                                 RLC                      R LC

                                                 MAC                      MA C

                                                Ph. Link                 Ph. Link
                                                and RF                   and RF


                                                Mobile                 BSC - SGSN
                                                                  Um    Network
              SNDCP: Subnetwork dependence Convergence Protocol
              LLC: Logical Link Control
              RLC: Radio Link Layer
                                                                         Ref: GSM 03.60 series
              MAC: Medium Access Control


                              Fig. 3.5a. GPRS architecture.




Fig. 3.5b. GPRS network.                                                    Fig. 3.5c. GPRS routing.

                                          3. Switching and Routing in Wireless Networking
20

Once the packets get to this point, they can be switched and routed by any kind of packet switching network
such as the Internet. The next step in the evolution of GPRS is Enhanced GPRS (EGPRS). This provides
for a higher radio interface rate and more flexible user rates. Enhanced Data Rates for Global Evolution
(EDGE) will be introduced to boost network capacity and increase the data rates of both circuit switching
using High Speed Circuit Switched Data (HSCSD) and packet switching (GPRS) up to three fold. Possible
rates may then exceed 400 kbps. The evolution of GPRS is believed by many to be the migration path
towards a Universal Mobile Telecommunication System (UMTS) and the UMTS Radio Access Network
(UTRAN)

Wireless ATM

An alternative contender for providing integrated wireless access and core network switching and routing is
Asynchronous Transfer Mode (ATM) or perhaps more properly called "cell switching." Originally
developed for wireline multimedia services, ATM has connection oriented features and the ability for
differentiated services and negotiated bandwidth plus Quality of Service (QoS) guarantees, that has much to
recommend it. One can build an entire end to end network based on ATM. Wireless ATM has become a
candidate architecture that assumes that multimedia service will be ATM based. Figure 3.6 illustrates the
basic architecture. In this structure, developed by NEC Research, the air interface is ATM cells and a special
ATM access point is provided to serve each geographical microcell. A new Mobile Network to Network
Interface (M-UNI/UNI) is added. The User to Network (UNI) is standard. If IP networking is required then
the proposal suggests carrying IP packets over ATM (IP/ATM).



                                                                                             R a i o Microc l l 1
                                                                                                d          e
                                                                 AT M ACCESS POI NT
                                                                                                          WAT M T E R MI NAL
                                                                                      WAT M c l l s
                                                                                             e
                                                AT M c l l s
                                                      e


                 AT M HOST /S E R V E R
                                          AT M SWI T CH                                                             Standard UNI (+M):
                                                                                      WATM Radio
                                          + Mob l i ty Ext
                                                i
                                                               Mobile ATM                                           ATM or IP/ATM
                                                                                      Air Interface
                                                               "M" UNI/NNI


                              Standard UNI:
                              ATM or IP/ATM
                                                                                             R a i o Microc l l 2
                                                                                                d          e




                                     Fig. 3.6. Network architecture: Wireless ATM system.

Shortcomings

Wireless ATM appears to have some serious shortcomings. For example, since Adaptation Layer 2 (AAL2)
appears to be the ideal mode to support both the radio interface and the core switching network, the use of
minicell packets (up to 42 octets) within AAL2 requires specific overhead for signaling and switching, the
result is a significant loss in efficiency. In addition, for high mobility users the Wireless ATM scheme may
not be easily scalable.

GPRS has its own problems in that it is a gradual approach to achieving the convergence objectives and in
the initial stages it is still tied to 2nd generation wireless techniques for roaming and mobility. Furthermore,
once the packet gets into the TCP/IP network, it is not distinguished from non-wireless traffic. Radio
transmission is notorious for its many impairments such as fading, multipath, shadowing, and blocking
which causes packets to be dropped or corrupted. The existing TCP protocols interpret this as congestion
and take action that can severely reduce performance. In addition, TCP/IP is a connectionless service with
no QoS guarantees and until new differentiated service features are introduced, a completely satisfactory

                                              Raymond L. Pickholtz                                               21

solution is not possible. Other problems exist in the interaction of the higher layers of the protocol stack
because of the anomalies of the physical layer that exists in wireless, and especially in high mobility and
handoffs.

Possibilities for Research

A possibly fruitful area of research for switching and routing in wireless networks is packet radio taken to its
limits. Packet radio per se has been investigated for many years as an application in military tactical
communications.

The ultimate solution may be to design the wireless network with an advanced version of packet radio more
suitable for the global commercial market. The large geographic coverage requires some form of cellular
structure where the mobiles act as relays to a cell site (or satellite) for long haul. In addition, the structure of
the network is very "fluid" so that "ad-hoc" networks may be established without prior configuration. There
is considerable research already underway for small scale ad-hoc wireless networks but that needs to be
extended.

There is also a need for understanding the interaction of the higher layers of the protocol stack when they are
being serviced by an unreliable and quirky wireless physical layer and the need for handoffs, mobility, and
roaming. A further positive note for direct wireless packet networks is that there are new protocol suites
such as Ipv6, which have a very large address space, built in security features and characteristics that
increase efficiency and performance. Another new direction in Internet development is Multiprotocol Label
Switching (MPLS), which bears directly on the issues of the ability to independently route and switch many
connections destined for the same address and allows a unique ability to optimize traffic flows and to
emulate connection-oriented virtual circuit switching. MPLS has been advanced by the Internet Engineering
Task Force (IETF). It is a label switching technique that integrates layer 2 switching with level 3 routing.
Label switched routers can improve performance and provide for differentiated services and multiple
protocols, including Ipv4 and Ipv6, among others. Although these ideas are being developed primarily with
the wired network, they have many potential benefits for the new multimedia broadband wireless systems.


CONCLUDING REMARKS

In the area of networking, switching and routing there will continue to be a disconnect between European,
Japanese, North American, and worldwide standards.

Even through the 3rd generation, the interfaces, signaling, and roaming will remain incompatible.
Furthermore, although there is every intention of providing higher data rates as well as voice telephony,
many systems are unable to integrate voice, data, and multimedia so that there is a smooth convergence of
wireline and wireless networks. The third generation migration of GSM includes GPRS, which is a
packetized transfer to the user level, but it is still based on connection oriented sessions by stealing slots
from the GSM TDM air interface. GPRS II extends the way that databases are accessed (for roaming, etc.)
but the basic architecture is the same. In the United States, there are similar methods for AMPS Cellular
Digital Packet Data (CDPD), the North American TDMA IS 136 standard, as well as Packet
communications in CDMA 2000. While there are many proposals to integrate ISDN, or ATM into the
wireless network, there remain fundamental problems with them.

Incorporating the ability to use IP for mobile traffic is fraught with problematic issues ranging from effects
during handoffs to roaming. Mobile IP as taken up by the IETF may be more suitable for relocation of
computer resources than to true mobility as in rapidly moving vehicles.

It appears that one way to achieve a true four-way convergence of wireline, wireless, telephony, and
multimedia traffic is to rethink the entire concept of leaving the core network as well as the air interface as a
connection oriented circuit switched network.

                                3. Switching and Routing in Wireless Networking
22

Among the topics of needed research are the following:
    a scalable architecture that takes into account the wireless access model
    seamless operation across radio access fixed and core network
    simplified mobility procedures
    distributed databases for user services
    new ideas of the use of intelligent network (IN) concepts applied to new services including mobile
     wireless
    a multi-tier structure that will allow expansion of scale and new services not yet defined

ACKNOWLEDGMENT

This author had the benefit of discussions with many people and, in particular, would like to thank Dr. Bijan
Jabbari of George Mason University for certain insights and Professor John Daigle and his student, Vikante
Chitre of the University of Mississippi, for permission to use Figures 3.4 and 3.5 on GPRS.

                                                                                                             23




                                               CHAPTER 4


    CHANNEL CHARACTERIZATION AND PROPAGATION MODELS FOR
              WIRELESS COMMUNICATION SYSTEMS

                                            Magdy F. Iskander




INTRODUCTION

A wide variety of radio propagation models for different wireless services that specifically address varying
propagation environments and operating frequency bands are generally known (Pahlavan et al. 1995; Jakes
1974). A large number of propagation prediction models have been developed for various terrain
irregularities, tunnels, urban streets and buildings, earth curvature, etc. (E. Vehicular Technology Society
1988; Lee 1989; Parsons et al. 1998). For propagation models addressing satellite communications systems,
on the other hand, different types of issues including rain attenuation and atmospheric effects are routinely
considered (Dissanayake et al. 1997). The level of sophistication in the development of these models also
depends on the longevity of the related technology. For example, the importance of developing propagation
models suitable for satellite communications, and in particular the development of reliable models for rain
attenuation and other atmospheric impairments along earth-satellite paths, has long been recognized; and
extensive research activities have been focused on addressing these effects (Capsoni et al. 1987; Stutzman
1995). With the development of new satellite services incorporating very small aperture terminals (VSAT)
and ultra small aperture terminals (USAT) in the Ka-band (20-30 GHz) frequencies, more recent research
efforts in this area have focused on refining available propagation models to account for and accurately
predict the total propagation link margin that includes other propagation impairments such as cloud
attenuation, gaseous absorption, and low-angle fading. European and U.S. agencies are compiling several
databases that should enable the evaluation of propagation models that attempt to combine different
propagation effects (Dissanayake 1997). These research activities and available results should also be useful
in addressing the needs of new emerging high frequency and point to multi-point terrestrial wireless
communication systems such as the local multi-point and point-to-point distribution systems (LMDS and
PPDS, respectively) and wireless local area networks.

With the phenomenal growth in mobile and portable terrestrial wireless communication systems, and due to
their potential utilization in a wide variety of high data rate and multimedia services, higher frequency bands
need to be allocated and utilized for these services. New devices and components for high frequency and
millimeter wave integrated front-end receivers are being developed, active and low cost phased array
antennas are being designed, and advanced software issues in coding, modulation, switching, and
networking are being researched and developed. In addition to these rather obvious advances that are
needed to enable the next generation wireless technology, developing new and more computationally
efficient propagation models is also essential. Development of reliable propagation models and the
availability of the associated simulation software tools would be absolutely necessary for the successful
implementation of the future terrestrial wireless systems and also for their integration with other technologies

           4. Channel Characterization and Propagation Models for Wireless Communication Systems
24

including the satellite, LMDS, and the wireline based services. Accurate propagation models will help in
using the rather congested frequency spectrum more efficiently, in planning more effective radio networks,
and in implementing cost effective solutions for a desirable and user specific communication coverage
pattern.


PROPAGATION MODELS FOR URBAN ENVIRONMENT

For urban propagation, three distinct models can be used. These include propagation in macrocells,
microcells, and indoor or picocells. In macrocells, the base station is often placed well above an average
rooftop, while for microcells the base station is placed well below the average rooftop. In macrocells, the
propagation path is dominated by the over the rooftop path, while for microcells reflections and diffraction
from buildings and streets often dominate the propagation environment. For such environments, ray tracing-
type simulation models are adequate and their use is justifiable. For picocells and indoor propagation, on the
other hand, new challenges appear and improved propagation models and simulation tools are required to
achieve reliable, accurate, and computationally efficient propagation predictions and to help overcome many
of the indoor propagation impairments. Challenges facing the development of picocell simulation tools may
include the following:
    Propagation predictions depend primarily on often unavailable building construction parameters such as
     wall thickness, materials, and indoor building structures.
    Exclusive use of ray tracing-based propagation models may be inadequate. Available ray tracing
     procedures often encounter a large number of reflections and multiple transmissions and hence become
     time consuming and computationally inefficient.
    Lack of knowledge of diffraction coefficients for many indoor structures may also compromise the
     accuracy of available ray tracing simulation methods.
    The ray tracing procedure and the geometrical theory of diffraction are high frequency techniques, and
     dimensions of some of the indoor structures may not necessarily satisfy the small dimensions compared
     to the wavelength criterion required by these methods.
It is often argued that results from deterministic electromagnetic-based calculation models are not expressed
in terms of parameters that can be used in the simulation of wireless communications systems. Parameters
such as delay spread, coverage, direction of arrival, and bit error rate (BER) are necessary for system
simulations and need to be incorporated as part of the simulation code development.

Four different types of methods are often used in developing propagation models, and the above listed
limitations are expected to impact them differently. For example, statistical models provide parameters
suitable for system simulations but lack specificity and accuracy. EM-based deterministic models, on the
other hand, provide accurate and site specific coverage and delay spread information but are also very
computationally inefficient and time consuming. Empirical and measurement-based models are site specific,
frequency specific, and hence lack generality. Researchers use a combination of these methods to help
improve the accuracy, broaden the generality, and reduce the required computational time. But much more
research and development are needed to fully develop accurate, computationally efficient, and
experimentally verified propagation models that may be used for broadband and highly mobile
communications systems. With the advances in the signal processing methods and the development of
communications algorithms, the envisioned propagation models are expected to play a critical role in the
accurate accounting for mobility and the dynamic variation in the characteristics of the propagation channels.

With this in mind, the panel members tried to identify and possibly discuss the on-going R&D activities in
this area of channel characterization and propagation models as we continued to travel in Europe and Japan.
Only at Philips, CSELT, and Ericsson in Europe, and Matsushita Research Institute Tokyo (MRIT), KDD,
and YRP in Japan did the panel identify research activities that the host was interested in sharing and
discussing. The following provides a summary of these activities and a comparative study of the level of

                                              Magdy F. Iskander                                              25

interest and the type of emphasis in each case. This summary will be presented according to the modeling
and the characterization technique used in research activities at the visited sites.

Deterministic EM-Based Propagation Models

The WTEC panel identified strong research activities in this area at Philips and Ericsson. At Philips, new
deterministic models for indoor propagation are being developed based on modal expansion techniques and
using the Finite Difference Time Domain Method (FDTD). In both cases, both the EM field distributions
and statistical parameters such as coverage and delay spread were being calculated (Dolmans 1997).
Examples of the obtained results using a 2D FDTD code are shown in Fig. 4.1 for two different indoor
propagation environments. Results from some of the statistical parameters calculations are shown in Fig. 4.2
where both the delay spread profile for propagating pulses of different widths and the coverage for single
and diversity antennas were calculated. Results from these calculations are being experimentally evaluated
using experimental set ups such as the one shown in Fig. 4.3. The important observation from this effort is
related to the fact that efforts are being made to include calculations of statistical parameters of interest to
system simulations and to verify the results experimentally. The use of 2D FDTD calculations emphasize
the need for a more computationally efficient procedure to carry out 3D calculations often required in indoor
simulations.

The research activities at Ericsson are closely tied with the European Cooperation in the Scientific and
Technical Research (COST) in this area.

The COST 295 task force on "Wireless Flexible Personalized Communications" has a working group
(Working Group 2) on propagation and antennas. This working group, chaired by Prof. E. Bonek from the
Technical University of Vienna, has the following stated objectives:
   develop new EM-based deterministic models for UHF, microwave, and millimeter wave
   study and optimize models for short range communications
   conduct a comparative study of the effectiveness of empirical/statistical and electromagnetic
    deterministic models for different propagation environments and situations
   conduct measurements to validate accuracy and improve efficiency

As part of this activity, Mr. M. Steinbaur, also from the Technical University of Vienna, is leading an effort
to provide characterization for wideband and time-varying directional channels and to ensure that models
meet requirements posed by system and network simulations. A summary of the progress and discussion of
activities of the COST 295 task force, working group 2, is available elsewhere (COST 295/260 Workshop
1999; Landstorfer 1999).




                          (a)                                                  ( b)
Fig. 4.1. Fluctuations of the electric field in the building that houses the faculty of Electrical Engineering.
          2D FDTD code was used in these calculations which include the following: (a) all doors are open
          with no object present; (b) doors are closed with one object placed in one of the rooms. Green
          color denotes high electric field values; blue color represents low signal amplitudes.

             4. Channel Characterization and Propagation Models for Wireless Communication Systems
26




                                                           Ex [V/m]
                                                                                      t [s]
                                             Delay profile of the electric field Ex
                                   t [s]




                                    (a)                                         (b)
       Fig. 4.2. Coverage distribution in an indoor environment using space diversity receivers (a) 0-100%,
                 (b) 98-100. The diversity combining consists of a switch (dashed-dotted), a selection
                 receiver (short dashes), an equal-gain combiner (dotted), a maximum-ratio combine (long
                 dashes). The coverage for a single antenna receiver is represented by the solid curve.




     Photograph of the measurement setup                   Schematic diagram of the measurement
     for a prototype of an adaptive DECT handset           set-up
     Fig. 4.3. A photograph and schematic diagram of the adaptive/diversity antenna measurement system
               (W.M.C. Dolmans, Eindhoven University of Technology/Philips Research Laboratory).

Ray Tracing-Based Propagation Models

The ray tracing method represents the most commonly used approach in the calculation of propagation
models for terrestrial and urban environments. Several software packages are available (Bertoni et al. 1994;
Liang et al. 1998; Rappaport et al. 1992), and some research efforts are underway to help in the continued
improvement of the accuracy and extension of generality and to increase computational efficiency. The
conventional ray tracing method is based on a ray launching and bouncing procedure that can be very
inefficient if no speed-up algorithm is employed. There have been several schemes to accelerate this
procedure including the image method, the bounding box method, and the utilization of the visibility

                                              Magdy F. Iskander                                                 27

approach (Landstorfer 1999; Liang et al. 1998; Catedra et al. 1998). Although these methods have their own
advantages and specific domains of applications, more efficient methods are needed to cope with the
complex and often computationally demanding indoor or indoor/outdoor situations while maintaining good
accuracy of the propagation prediction results. Such research activities were found at CSELT in Italy and
KDD Research and Development Laboratories in Japan. At CSELT results from several models were
presented including site specific ray tracing predictions which were time consuming; ray-launching results,
which were faster but lacked accuracy; and semi-deterministic methods, which were being used in small cell
planning. For indoor propagation, however, empirical models based on experimental measurements were
being used. Results from these calculations were presented in terms of field distributions in the propagating
environment, delay spread distribution, and Doppler frequency distribution. An example of the presented
results for a microcellular structure is shown in Fig. 4.4.




   Fig. 4.4. Microcell structure (L.) and ray tracing results (R.) of delay profile in a parking lot (CSELT).

At KDD two tools were developed. These include the CSPLAN tool, which is used for cell site planning and
coverage evaluation using low antenna height and 2D building shapes, and the BSPLA tool, which provides
propagation predictions for mobile based station planning. For the BSPLA tool, path loss is evaluated based
on geographic information of the propagation area. This effort at KDD points to other ongoing research
activities in the area of channel characterization and propagation models development, including the use of
geographic information and data from the Global Positioning System (GPS) to guide the development and
enhance the accuracy and the computational efficiency of new propagation models for future wireless
communications systems (Enge 1994; Kaplan 1996). This may provide significant advantages in systems
that intend to incorporate dynamic variations in channel characteristics. For mobile multimedia wireless
applications, incorporation of such capabilities may be crucial in enhancing the quality of service or making
it even possible in the first place.

Propagation Models At Millimeter Waves

Besides the stated objective by the COST 295 working group, the issue of developing propagation models at
millimeter wave frequencies was not discussed in any of the visited European sites. Two groups in Japan,
however, discussed R&D activities in this area. These include the MRIT and the Stratospheric Wireless
Access Network group at the Yokusuka Research Park (YRP). At MRIT new propagation models are being
developed at millimeter wave frequencies, and emphasis is placed on the accurate accounting of multi-path
analysis. At YRP, on the other hand, propagation models are being developed to support the development of
a stratospheric platform. This unmanned High Altitude Platform Station (HAPS) is expected to fly at an
altitude of 22 km, and 15 platforms are expected to provide coverage for all of Japan. Frequencies in the
range from 2-20 GHz will be used with the continued increase in attainable data rates. Figure 4.5 shows that
optical links will be used for inter-platform communications and radio links will be used for subscriber

           4. Channel Characterization and Propagation Models for Wireless Communication Systems
28

access. Propagation models that cover this entire frequency band are being developed, and research
activities expected to improve the accuracy and enhance the computational efficiency will continue for some
time.




                 Fig. 4.5. Schematic of the stratospheric wireless access network in Japan.

Empirical and Measurement-Based Propagation Models

Clearly many of these models are presently available and are being used in a variety of wireless services.
Limited aspects of these models were, however, discussed in the visited sites during this study. As
mentioned earlier, the COST 295 task force is involved in a comparative study of the effectiveness of
empirical and statistical vs. electromagnetic deterministic models in different situations. The CSELT group
is also using this type of empirical model for indoor propagation studies and channel predictions. The
limited interest in this area may be justified based on several drawbacks including the following:
    the large number of time-consuming measurements required
    the site specific nature of the data and their limited broad utilization in various propagation
     environments
    lack of accuracy
The main reason for the attractiveness of such approaches is computation speed. Furthermore, results from
these measurements and empirical curve fitting efforts are sometimes used to complement ray tracing-type
calculations and provide improved accuracy in areas where it is difficult or time consuming to incorporate
numerical calculations of diffraction coefficients.

Technology Assessment

In addition to the information learned and collected during site visits, the WTEC panel tried to further assess
research activities in this area by searching the INSPEC database for some of the key words related to this
topic. Selected key words include propagation models, channel characterization, and indoor-outdoor
propagation models. The results from the database search are summarized in tables 4.1a, 4.1b, and 4.1c in
terms of the number of papers published or presented on this subject. From these results it may be noted that
research on the development of propagation models is strongest in Europe, followed by the United States,
while the research activities in the area of indoor-outdoor propagation models are rather limited (only 20

                                                 Magdy F. Iskander                                          29

papers cited during the period from 1995-99) with major participation by the European community. These
results also emphasize the need for new R&D for modeling micro- and pico-cells.

                                               Table 4.1a
                                     Propagation Models (1998-1999)*
                                         U.S.A.          21          21%
                                         Europe          38          38%
                                         Japan            8          8%
                                         Canada           6          6%
                                         Others          27          27%
                    *Results of the database search using INSPEC. Total number of papers, 100.

                                              Table 4.1b
                                  Channel Characterization (1997-1999)*
                                         U.S.A.          16          38%
                                         Europe          19          45%
                                         Japan            1          2.4%
                                         Canada           2          4.8%
                                         Others           4          9.5%
                                            *total number of papers 42

                                              Table 4.1c
                                Indoor-Outdoor Propagation (1995-1999)*
                                         U.S.A.           3          15%
                                         Europe           9          45%
                                         Japan            1          5%
                                         Canada           2          10%
                                         Others           5          25%
                                            *total number of papers 20

For the overall comparative study among Europe, Japan, and United States in the area of channel
characterization and modeling, Table 4.2 was prepared to provide a qualitative comparison. From Table 4.2
it may be noted that while the majority of the available models are based on the computationally efficient
statistical and empirical models, there is some growing interest in using EM-based deterministic models
particularly in the United States followed by Europe. Efforts to integrate statistical parameters in the models
are being mostly emphasized in Europe followed by the United States. It is expected that this trend will
continue to grow because of the continued demand for improved accuracy and reliability in system designs
and network planning. Table 4.2 also shows some growing interest in modeling new wireless
communications systems in the millimeter wave frequency range in both Japan and the United States, while
much of the European activity is presently focused on addressing the present industrial needs at lower RF
frequencies.

              4. Channel Characterization and Propagation Models for Wireless Communication Systems
30

                                                     Table 4.2
                             Research Activities in the Channel Characterization and
                            Propagation Models in Europe, Japan and the United States
                                                                     Europe               Japan                 USA
    Statistical/empirical                                              ***                  ***                  ***
    EM based deterministic                                              **                   *                   ***
    Integrative models                                                  **                   -                    *
    (Statistical parameters based on deterministic models)
    Microwave and millimeter wave                                       *                   **                   **
*Qualitative results of a comparative study illustrating the level of activities and the focus of research in Europe, Japan,
and the United States in the area of channel characterization and propagation models.


KEY RESEARCH ISSUES

From the preceding discussion and keeping in mind the stated vision for next generation wireless technology
of fully integrated, reliable, multimedia services with full mobility and minimum latency, the following key
research activities in the channel characterization and propagation model development may be suggested:
     new models for microwave and millimeter wave wireless systems
     models for broadband wireless systems including polarization diversity and mobility effects
     computationally efficient deterministic/quasi-deterministic models that maintain good accuracy and
      generality of application
     integrated models that provide statistical parameters relevant to system and network simulations
     experimental measurements on scaled models or realistic channels to validate simulation results and
      provide guidance for identifying the most important contributions to propagation impairments and
      interference effects
While emphasis in this chapter was placed on channel characterization and propagation models, it is
important to point out that multidisciplinary efforts that incorporate knowledge of the channel characteristics
to develop and implement novel signal processing methods, communication algorithms, and networking
protocols represent a most effective strategy in advancing wireless communications systems. Every effort
should be made to participate in these integrative and multidisciplinary approaches rather than focusing on
isolated and individual efforts in channel characterization and modeling.

In addition to the need for integrative efforts, there is no question that research efforts must focus on the
development of a physics-based channel model that effectively takes advantage of the identified dominant
effects in a given propagation environment and frequency band while maintaining good accuracy. A broad
range of applicability and acceptable computational efficiency will provide next generation wireless
communications systems with a significant tool and a most valuable enabling technology. Understanding the
physical nature of the wireless communication channel and incorporating this developed fundamental
understanding across the communications layers is crucial for realizing the much anticipated benefits from
the wireless information technology and networks.


REFERENCES

Bertoni, H.L., W. Honcharenko, L. R. Maciel, and H. H. Xia. 1994. "UHF propagation prediction for wireless personal
     communications." Proceedings of IEEE 82:1333-1359.
Capsoni, C., F. Fedi, and A. Paraboni. 1987. "A comprehensive meteorologically oriented methodology for the
    prediction of wave propagation parameters in telecommunication applications beyond 10 GHz." Radio Science
    22:387-393.

                                                 Magdy F. Iskander                                                  31

Catedra, M.F., J. Perez, de Adana, and Gutierrez. 1998. "Efficient ray-tracing technique for 3D analyses of propagation
    in mobile communications: application to picocells and microcell scenarios." IEEE Antennas and Propagation. 40
    (2):15-28.
Dissanayake, A., J. Allnutt, and F. Haidara. 1997. "A prediction model that combines rain attenuation and other
    propagation impairments along Earth-satellite paths." IEEE Trans. Antennas and Propagation 45 (10):1546-1557.
Dolmans, W.M.C. 1997. "Effect of indoor fading on the performance of adaptive antenna system." Ph.D. dissertation,
    Department of Electrical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.
E Vehicular Technology Society. 1988. "Special issue on mobile radio propagation." IEEE Tran. Veh. Technol. 37:3-
    72.
Enge, P.K. 1994. "Global positioning systems: signals, measurements, and performance." International J. Wireless
    Information Networks 1(2).
Jakes, C., ed.. 1974. Microwave Mobile Communications. New York: John Wiley & Sons.
Kaplan, E.D., ed. 1996. Understanding GPS: Principles and Applications Boston: Artech House.
Landstorfer, F. 1999. "Wave propagation models for the panning of mobile communication networks." Plenary
    presentation read at European Microwave Conference, 4-8 October, Munich, Germany.
Lee, Y. 1989. Mobile Cellular Telecommunications Systems. New York: McGraw-Hill.
Liang, G. and H. L. Bertoni. 1998. "A new approach to 3-D ray tracing for propagation prediction in cities," IEEE
    Trans. Antennas and Propagation 46:853-863.
Pahlavan and A.H. Levesque. 1995. Wireless Information Networks. New York: John Wiley & Sons.
Parsons, J.D. and J.G. Gardiner. 1998. Mobile Communication Systems. Glasgow: Blackie.
Proceedings of COST295/260 Joint Workshop. 1999. "Spatial Channel Models and Adaptive Antennas." April 20-21,
    Vienna, Austria.
Rappaport, T.S. and D.A. Hawbaker. 1992. "A ray tracing technique to predict path loss and delay spread inside
    buildings." Proc. IEEE GLOBCOM'92 Dec: 649-653.
Stutzman, W.L., T. Pratt, A. Safaai-Jazi, P.W. Remaklus, J. Laster, B. Nelson, and H. Ajaz. 1995. "Results from
     Virginia Tech propagation experiment using the Olympus Satellite 12, 20, and 30 GHz Beacons." IEEE Trans.
     Antennas and Propagation 43 (Jan): 54-62.

     4. Channel Characterization and Propagation Models for Wireless Communication Systems
32

                                                                                                              33




                                               CHAPTER 5


    HARDWARE FOR RF FRONT-END OF WIRELESS COMMUNICATION

                                        Tatsuo Itoh, Linda Katehi




INTRODUCTION

Hardware provides the building blocks for the specified requirements and functions of wireless
communication systems. In many defense and satellite systems, devices and circuit designs are aimed at the
best performance, although the choice of hardware is often conservative. In the case of wireless
communication systems, this conservative approach is somewhat true because of the rapid turnaround in
commercial products. In fact, manufacturability and marketability become the drivers for many high volume
short-cycle commercial products as many industrial participants in this study like Dr. J. Golio of Rockwell
emphasized. However, in looking at the future beyond the G3 and even G4 environment, research
concerning hardware needs to be advanced in a steady and accelerated pace. This includes not only devices
and circuits, but also enabling process technology and design methodologies. This is because the
performance of future wireless systems critically depends on hardware capability. Dr. Golio mentioned that
the faster, smaller, lighter and cheaper philosophy still holds. It is also true that research methodologies for
hardware may need to be modified.

One of the factors influencing hardware research is the frequency of operation, which affects bandwidth and
signal processing speed. Although much industrial effort is aiming at frequencies up to 2.4 GHz (at most 5.7
GHz) for mobile wireless and 28 GHz for fixed wireless such as LMDS, several industrial research centers
are looking at much higher frequencies beyond 60 GHz. Although the need for bandwidth far exceeding the
G3 requirement is often questioned, research on higher frequency devices and circuits has at least two
benefits. One is to enable a potential system that takes advantage of the wider bandwidth such as 5 GHz
around a carrier frequency of 60 GHz, as envisioned by Sony for ultra-wideband wireless connections.
Another is to make low frequency design more flexible and device and circuit performance superior through
the availability of higher frequency devices used lightly.

Since hardware research is motivated by system requirements, listing some of the desired features for the
future systems and the potential technologies necessary to achieve these goals is a good place to begin. The
list is not intended to be exhaustive, but it includes features envisioned by some industrial participants in the
WTEC study. Dr. Walid Ali-Ahmad of Maxim, who is engaged primarily in silicon based wireless systems,
provided the following list of targets for future circuits and devices:
   complete wireless system on chip including radio frequency (RF), analog baseband, digital baseband,
    digital logic, digital signal processing (DSP), microprocessor and power supply1


1
 At the recent Workshop on Single Chip Radio during the 1999 IEEE International Microwave Symposium, most
panelists expressed the desirability (but extreme difficulty) in achieving this in the foreseeable future.

                           5. Hardware for RF Front-End of Wireless Communication
34

    low cost system solution with minimum off-chip component count, high yield process
    small size system solution and portability
    very low power consumption and extended battery life

Dr. Ali-Ahmad provided the following list of device and circuit technologies needed:
    MEMS devices and micromachined components including the high-Q on-chip filters
    advanced IF circuits for software radio
    advanced process technology
    optimized RF silicon transistors for high efficiency linear power amplifiers
    continued scaling of complementary metal oxide semiconductor (CMOS) technology
    advanced packaging
    battery technology
    CAD for system-on-chip design

In regard to the device technology, a number of other study participants from the United States and abroad
emphasized the importance of III-V devices for high frequency applications such as 5.7 and 60 GHz (Mr.
Kawasaki of Sony, Dr. K. Honjo of NEC, Dr. Kagiwada of TRW). In fact, TRW can deliver a 190 GHz
amplifier based on III-V technology. On the other hand, many people considered SiGe as a promising
device with potential low cost, high frequency applications.


CMOS TECHNOLOGIES AND SILICON BIPOLAR TRANSISTORS

CMOS and silicon bipolar devices and circuits currently are responsible for the majority of wireless
communication hardware. Silicon technology has a long history for digital signal processing, VLSI, A/D
and D/A converters. CMOS based radio has been steadily progressing toward higher frequencies. State-of-
the-art CMOS uses the 0.18 m process. CMOS is currently the workhorse for wireless up to 800 MHz.
Substantial effort is being expended worldwide to extend the frequency to 1.9 GHz, 2.5 GHz and 5 GHz
ranges. One of the major drawbacks for silicon devices used for RF applications is the low resistivity of
silicon, causing substrate loss. This problem causes low Q of passive circuits, particularly for inductors.
Much effort is spent to enhance the capability of silicon circuits by, e.g., elevating the inductor from the chip
to increase Q and by introducing SOI (silicon on insulator) technology for power and speed.

Philips Research Laboratories have been working on "silicon-on-anything" devices based on the bipolar
process with the circuits transferred to a range of insulating substrates such as glass (Fig. 5.1). In this way
the parasitic capacitance is reduced, and high-quality RF passive components can be integrated on the chip.
They have manufactured RF devices, including a bipolar transistor with an active emitter of only 0.05 square
micrometers and with proportionately smaller junction capacitances. This resulted in low power
consumption with only 15 A at the cut-off frequency of 10 GHz. One example of the chips is a fully
integrated LC-type VCO including a phase-locked-loop frequency synthesizer and divider chain for local
area networks (LANs).

Much effort has been expended to improve performance by changing the device fabrication process. For
example, Philips has proposed a double-poly-transistor with SiGe in-situ grown base (Fig. 5.2). The
traditional base contacts are eliminated. Instead, the base contacts are poly-silicon strips on a thick oxide
layer. The base layer is grown into the narrow opening in the oxide and automatically contacts the poly-
silicon strips. Finally, heavily n-doped poly-silicon is deposited to form the emitter. Adding 10 to 20% Ge
to the base layer offers new possibilities to adjust device parameters.

                                          Tatsuo Itoh, Linda Katehi                                        35




           Fig. 5.1. An example of a silicon-on-anything circuit by Philips Research Laboratory.




                      Fig. 5.2. Double-poly transistor by Philips Research Laboratory.

Although it has not used CMOS, NEC has utilized Si nMOSFETs (field-effect transistors) for both a low
frequency (900 MHz) amplifier for GSM and high frequency (Ku band) amplifier (Fig. 5.3). Since the
substrate is lossy, the amplifier design for 900 MHz makes use of the loss matching technique to obtain an
unconditional stability from a conditionally stable design to obtain a power added efficiency (PAE) of 62%
with the power output Pout of 27 dBm. The device uses two-generation old 0.6 m technology. For the Ku
band amplifier based on 0.18 m nMOS (with fT of 50 GHz and fmax of 45 GHz), the substrate loss is too
significant to use the same approach. Therefore, the transmission line structures for the circuit are modified
(Fig. 5.4). For "Type A" modification, microstrip lines are placed on a polyimide layer that is in turn placed
on Si substrate via SiO2 and SiON isolation layer. In "Type B," a thin-film microstrip line that has an Al
layer inserted in the SiON and SiO2 layers is used. The insertion loss is about 1 dB/cm. The amplifier gain
is 10 dB with a noise figure of 4 ~ 5 dB in Ku band.

One technology that has drawn recent attention is SOI (silicon on insulator). Recently IBM announced that
it plans to use SOI technology to manufacture a range of logic integrated circuits (ICs). IBM's first
0.22 micron SOI devices were scheduled to be used in Apple Computer Inc.'s Macintosh systems and in
IBM servers, perhaps by early in the year 2000. IBM is also developing 0.18 and 0.13 micron processes for
1 GHz microprocessors. Along with up to 30 percent performance gains, SOI could improve power
consumption by 30 to 50 percent. Because SOI's advantage is more pronounced at low-voltage operation,
the technology is suitable for mobile applications, with reasonable RF performance at single-volt supply
voltages well above a few GHz. Similarly, Motorola is preparing an SOI BiCMOS process for RF/IF
circuits for cellular phone applications.

                          5. Hardware for RF Front-End of Wireless Communication
36




                                Fig. 5.3. nMOSFET characteristics by NEC.




                        Fig. 5.4. Transmission lines on an Si substrate used by NEC.

Many modern wireless communication systems use digitally modulated signals. Therefore, at some point
this digital information needs to be extracted so that DSP can take over. Much work has been carried out for
the direct conversion receiver. Central to this scheme are AD and DA converters. Although there is a need
to place this A to D conversion scheme as close to the antenna as possible, the performance of the AD and
DA converters set the limit (Fig. 5.5). The bit rate and the frequency are in a trade-off relationship. Analog
to digital conversion improves 1 bit/3 years according to Philips, and CMOS AD conversion may slow down
due to low VDD. In fact, a good rule of thumb to describe a figure-of-merit of the AD converter is given by

                   F = log2(Sampling Speed) + Resolution (given as Effective No. of bits)

For the state of the art, this F value ranges from 38 to 40 at the moment. For example, for 1 GHz speed with
10 bits of resolution, F becomes 40.

                                          Tatsuo Itoh, Linda Katehi                                       37




             Fig. 5.5. Recent and projected trends for AD conversion for 1990-2002 (Philips).


III-V DEVICES AND CIRCUITS

Although the market is much smaller than that for silicon based devices, III-V devices have been developed
for high performance, high frequency applications from UHF to millimeter-wave frequencies. In addition to
the discrete devices, the past several years have seen significant advances in MMIC based on III-V materials.
The most common baseline materials are GaAs and InP. GaAs metal Schottky FETs (MESFETs) are quite
mature and are available off the shelf up to X and Ku band applications. More advanced high electron
mobility transistor (HEMT) devices are the preferred choice for higher frequency and higher performance
applications with lower noise figures for low noise amplifiers. InP HEMT provides better performance for
higher millimeter wave frequencies as demonstrated by Daimler-Chrysler in Fig. 5.6.




                              Fig. 5.6. Daimler-Chrysler InP-based HEMTs.

TRW recently demonstrated the world's first 190 GHz InP HEMT low noise amplifier (LNA), which
exhibited a gain of more than 7 dB from 160  190 GHz, with a peak of 9.6 dB, while the noise figure is
6 dB at 170 GHz (see Fig. 5.7). This device has a 70 nm e-beam defined T-gate on a 2-mil substrate with a
25 m backside via. TRW also has demonstrated an InP HEMT MMIC power amplifier with an output
power of 427 mW with PAE of 19% and an associated gain of 8.2 dB (see Fig. 5.8). The state of the art
devices exhibit fT > 300 GHz and fmax > 500 GHz. The expected future performance would be fT > 500 GHz,
fmax > 1 THz, and an LNA with a gain of 10 dB at 260 GHz, as well as a PA with an output power of 0.25 W
at 260 GHz.

                         5. Hardware for RF Front-End of Wireless Communication
38




                         Fig. 5.7. TRW 190 GHz InP HEMT low noise amplifier.




                           Fig. 5.8. TRW W-band In-P HEMT power amplifier.

For applications at somewhat lower frequencies, GaAs HEMT (PHEMT or pseudomorphic HEMT) is a very
practical and readily available device. In fact, Dr. Honjo of NEC believes that wireless applications up to
100 GHz do not require the use of InP devices. For future mobile wireless communications for multimedia,
a high speed (> 20 GHz) and low power phase lock loop (PLL) is required. NEC has developed a CPW-
based MMIC using a 0.1 m GaAs E/D-HEMT. The salient feature of this device is the use of a two stage
mushroom gate (see Fig. 5.9).

                                          Tatsuo Itoh, Linda Katehi                                        39




                              Fig. 5.9. NEC two-stage mushroom gate HEMT.

A new type of microwave device that has drawn a considerable research attention is III-V heterojunction
bipolar transistor (HBT). This device tends to have a lower phase noise than FET type devices. At the
moment, the usable frequency range is lower, however. NEC uses selective regrowth to reduce the base
resistance to one fourth (see Fig. 5.10). At the same time, pseudomorphic InGaAs graded base was used so
that the regrowth-performed GaAs-based HBT achieved low RbCbc leading to an fmax comparable to those of
high-performance InP-based HBT that has a higher fT. Some of their devices include (1) a 26 GHz power
amplifier module made of two device power combined with 3.63 W and PAE of 21%, (2) a 1W 35 GHz
HBT power amplifier with PAE of 29% and a 60 GHz dynamic frequency divider, and (3) a low phase noise
38 GHz HBT MMIC VCO.




                                 Fig. 5.10. NEC high fmax HBT technology.


SiGe DEVICES AND CIRCUITS

To achieve high integration and multifunction capability, industry is pursuing the development of SiGe for
range sensors, speed control, etc. In addition to integration and performance, this technology is likely to be
utilized in customer products for wireless applications including communications and sensing/navigation.
Comparisons made between InP-, GaN- and SiGe-based products show superior cost potential in the SiGe
technology (see Fig. 5.11) and indicate device superiority due to very low 1/f noise and low phase noise.
SiGe transit-time diodes in self-oscillating mixers have demonstrated frequency stability with subharmonic

                                                     5. Hardware for RF Front-End of Wireless Communication
40

locking. Free running has demonstrated about -60 dBc/Hz at 100 kHz from the carrier, and with phase
locking about 90 dBc/Hz at 100 kHz from the carrier. In this circuit technology, CPW has been chosen as
the interconnect medium due to its superiority to thin film microstrip and its associated need of a via hole
technology. CPW solves a number of problems but requires an air-bridge technology, which in terms of
fabricating is easier to establish due to its requirements for wafer-surface and not wafer-bulk fabrication.
Daimler-Chrysler is a leader in SiGe technology and has demonstrated performance records in SiGe HBT, as
shown in Fig. 5.12. A number of SiGe applications include Ka-Band CPW oscillator HBTs, a 77 GHz near-
field sensor with SiGe Schottky diodes, a 77 GHz closing velocity sensor, etc. While SiGe technology is
progressing fast, a number of processing issues still need to be resolved. To alleviate some of these issues,
passivation of the device by Si3N4 has been adopted. Low temperature, low-power cpw-based HBT
structures are routinely demonstrated (20 mW at 47 GHz) (6 emitter figure device). Presently research is
focused on the development of phase resonant devices with fmax=300GHz achieved by quantum-well
injection.

                                                    SiGeSIMMWIC: Motivation
                                                     Mater ial data and costs

                                                                                                                                            Silizium                                                         GaAs

                                                                                                                                             11,67
                                                                Pe mittivity
                                                                  r                                                                                                                                           12,7
                                                                                                                                          1500 c 2/Vs                                                     8500 c 2/Vs
                                                                                                                                                m
                                                                Ele tron mobility
                                                                   c                                                                                                                                             m
                                                                                                                                          3 x 105 V/c                                                     4 x 105 V/c
                                                                Bre kdow fie d
                                                                   a    nl                                                                           m                                                               m
                                                                The mal c nduc ivity
                                                                   r     o     t                                                           1,5 W/c K
                                                                                                                                                  m                                                       0,46 W/c K
                                                                                                                                                                                                                  m
                                                                Me hanic l s ability
                                                                  c     at                                                                    hoch                                             ge ing
                                                                                                                                                                                                 r
                                                                Subs ratec s
                                                                    t     ot                                                            < DM 10 - 6" (low                                 DM 200 - 3" (s mi-
                                                                                                                                                                                                        e
                                                                                                                                          re is ivity)
                                                                                                                                            st                                                            ins lating)
                                                                                                                                                                                                             u
                                                                                                                                        DM 30 - 4" (high
                                                                                                                                           re is ivity)
                                                                                                                                             st
                                                                                                                                     Good RF pe formanc data of GaAs
                                                                                                                                               r       e

                                                                                                                                     Cos advantage(1 orde of magnitude of s lic n !
                                                                                                                                        t                r            )    io


                                             Fig. 5.11. Comparison of GaAs and SiGe (Daimler-Chrysler).




               SiGeSIMMWIC: (Module )    s
                 Per for mance - world-record !
                                                                                                                                                                                                                         100 kHz
                                                                                                                                                                                                                                               S pan: 1MHz
                                                                                             Monolithical integrated                                                                                  0
                                                                                                                                                                                                                                               VBW: 10 kHz
                                                                                                                                                                             output power (dbm)




                                                                                                                                                                                                                                               RBW: 10 kHz
                                                                                             coplanar 6 finger                                                                                                         59.31 dBc
                                                                                                                                                                                                   -20

                                                                                             HBT structure
                                                                                                                                                                                                   -40


                                                                                                                                                                                                   -60


                                                                                                                                                                                                   -80
                                                                                                                                                                                                   47.0224   47.0226   47.0228     47.0230   47.0232   47.0234
                                                                                                                                    Power density spectrum                                                              fr equency (G z)
                                                                                                                                                                                                                                     H




                                                                                                                                    Power vs
                                        15                                                    47.04
                                                                                                      oscillation frequency (G z)




                                                                                                                                                                                                                                                        47.04
                                                                                                                                                                                           14
                                                                                                                                                                                                                                                                 oscillation frequency (G z)
                                                                                                                              H




                                                                                                                                                                                                                                                                                         H




                                                                                                                                    Collector voltage
                   output power (dbm)




                                                                                                                                                                output power (dbm)




                                        10                                                    47.02                                                                                                                                                     47.02
                                                                                                                                                                                           12


                                                                                                                                                                                                                                                        47.00
                                                                                                                                                                                           10
                                        5                                                     47.00

                                                                                                                                                                                                                                                        46.98
                                                                                                                                                                                                  8
                                        0                                                     46.98

                                                                                                                                                                                                                                                        46.96
                                                                                                                                                                                                  6
                                        -5                                                    46.96
                                                                                                                                         Power vs                                                 -0.84        -0.82         -0.80            -0.78
                                             1.5   2.0    2.5    3.0     3.5    4.0    4.5
                                                                                                                                         Emitter voltage                                                     emi tter -bas e voltage veb (V)
                                                   coll ector -bas e voltage vcb (V)




                  Fig. 5.12. World record performance of SiGe HBTs (Daimler-Chrysler).

Daimler-Chrysler is inserting this technology into customer products via an extensive product development
effort performed in the "Microwave Factory" owned by DASA. Sensors have been produced such as
SatCom, MobilCom, Cruise control at 77 GHz and LMDS at 28 GHz, in addition to 24 GHz radar designed

                                           Tatsuo Itoh, Linda Katehi                                        41

to measure material properties for application in steel production. Other products include a 58 GHz point-to-
point link in hybrid configuration with GaAs MMICs using bonding wires for connection to MMIC chips.


GaN DEVICES AND CIRCUITS

Devices based on a wide bandgap semiconductors also have received considerable attention. In particular,
GaN based devices are considered more appropriate for higher frequency operations than SiC based ones.
Although GaN has been successfully applied for blue laser development, its microwave application has
encountered a number of challenging research issues, two of which are material purity and substrate
material. Daimler-Chrysler, for example, uses material from Cree and silicon carbide substrate for X band
high power application (10 W/mm at 50 V bias) (see Fig. 5.13). NEC has attained fmax of 90 GHz with an SiC
substrate. This device, when matured, is promising for the base station applications.




                                   Fig. 5.13. Daimler-Chrysler GaN FET.


MILLIMETER-WAVE CPW MMIC

At UHF to lower microwave frequencies, RF front-end circuits are primarily made by monolithic microwave
integrated circuits (MMIC). The typical MMIC makes use of microstrip line technologies for which
sufficiently accurate and fast CAD software is available, and industry all over the world has sufficient design
experience. At higher microwave frequencies to millimeter wave frequencies beyond 60 GHz, a microstrip
line is not necessarily the best choice, while coplanar waveguide (CPW) technology has received
considerable attention. At this time, CAD tools for CPW are not completely satisfactory. CPW has much
smaller dispersion in phase velocity and has a more tightly coupled electromagnetic guided field than
microstrips and many other guided wave structures. In addition, its uniplanar nature does not require a via-
hole process due to lack of the backside ground plane while air-bridges are required. IMST in Germany has
spent considerable effort in establishing design techniques for CPW, primarily based on lumped element
approximations. A number of corporations visited by the WTEC panel, including Daimler-Chrysler and
NEC (see Fig. 5.14), now make use of CPW for millimeter-wave MMIC development.

                          5. Hardware for RF Front-End of Wireless Communication
42




                                   Fig. 5.14. NEC 60 GHz CPW MMIC.

Use of CPW and slot line in MMIC have been core research items at NTT Wireless Systems Laboratory. Its
Uniplanar MMIC can reduce the chip size to 1/1.5 to 1/5 in comparison with the microstrip line based
MMIC. NTT has further advanced research toward 3D MMIC, which is discussed later in this chapter.


HIGH Q COMPONENTS AND FILTERS

Murata holds a very strong position in the manufacture of high-Q components and filters through the
development of novel ceramic materials and devices. Its success is based largely on the ability to develop
unique designs of ceramics materials, employ a low-cost manufacturing process, and design useful devices
incorporating these materials better and cheaper than probably anyone else. Murata's technology policy
leads to the integration of material, processing, design and production processes. This approach is followed
in all component and element design. About 10 billion capacitors are produced per month. Murata has
extensive tools for design and analysis and has developed its own manufacturing equipment. Material
characterization is performed via resonator measurements using HP equipment. Murata's method will
become an IC standard next year.

Most of the high-Q components and filters are based on the company's ceramic material formulations
combining high dielectric constant with high Q (low dielectric loss), and good thermal stability in both
dielectric constant and temperature coefficient of expansion. Murata ceramics are known as the best in the
world. Dielectric constants range from 20 to 13,000. A value of 3000 is most popular. Ceramic dielectric
constants are notoriously temperature sensitive, but one material changed only 10 percent from -45C to
+85C.

Filters are developed via use of piezoelectric materials (PZT) and multilayer technology for very low
frequency applications from the 400 kHz region up to 10 MHz. In addition, ferrite materials are used to
develop transformers and noise suppression filters. Pyroelectricity is a material property explored for sensor
development. Furthermore, semiconductor materials are used for the development of thermistors. The kind
of device used for filtering depends inter alia on frequency and power levels. Thus SAW filters are good at
lower power levels and better at the lower frequencies. Piezoelectric filters have been used up to 450 kHz
with an unloaded Q of 400 and only about 1/2 mm on the side.

                                           Tatsuo Itoh, Linda Katehi                                          43

Murata has a good capability to design microwave combline and stepped-impedance filters and duplexers to
specified performance. These dielectric filters are constructed in a neat miniaturized monoblock
construction out of a block of high-dielectric-constant material (under the trade name GIGAFIL). Murata
has written its own proprietary CAD programs to aid in various designs. It has demonstrated progress in
miniaturization by showing successive versions of two 900 MHz GIGAFIL duplexers: the mobile version
came down from 66 cc in volume and 154 g in mass in 1983 to 3.9 cc and 20 g, respectively, in 1996. The
handheld version went from 9.5 cc and 30 g in 1986 to 0.9 cc and 3 g in 1995 (and 0.5 cc in 1997). Murata's
work on both dielectric block filters and on multilayer functional substrates is particularly impressive, both
leading to miniaturized high-performance components. The latter starts out with thin strips of green ceramic
piled in layers. One such device consisted of 21 layers; as many as 600 layers have been contemplated, but
not made. The fabrication steps are briefly stated as follows: Mix materials, de-air, make sheets, cut sheets,
punch via holes, fill via holes, add dielectric material + solvent + binder, print inner electrode, punch cavity,
stack, press, form grooves (for later breaking into separate modules), cofire, inspect, plate Au/Ni electrode,
print solder paste, mount components, solder, break where grooved, package and mark, inspect, pack and
ship. Filter technology goes to 2 micron thickness, which is expected to be reduced further to reach the 1
GHz mark. The transverse dimension may be as high as a few millimeters.

A major trend in filter technology is the constant push toward three-dimensional (3D) micro-miniaturization,
as evidenced here by the multilayer construction currently attempted in filter design. The driver is smaller
size, lower mass, lower cost, and sometimes better performance (afforded by integration and the avoidance
of connectors and connecting 50-ohm cables). Research into better ways to accomplish this miniaturization
might have good payoff though this is perhaps several years away.


PACKAGING AND INTEGRATION

Packaging and integration of the entire radio including the RF front end is one of the most expensive
portions of wireless hardware. The ultimate goal could be the so-called system-on-the-chip in which all the
constituent elements of wireless communication hardware are in a single chip including the baseband DSP,
RF-front end, and even antennas. In practice, however, the approach is to combine several different chips or
functional elements and connect them together to form a functional block. The so-called multi-chip module
(MCM) of this type. In many attempts, the techniques developed at lower frequencies can be modified for
high frequency applications. Flip-chip mounting of the MMIC on a motherboard is one such example (see
Fig. 5.15).




                           Fig. 5.15. A typical flip-chip MMIC structure by NEC.

                          5. Hardware for RF Front-End of Wireless Communication
44

Matsushita Research Institute Tokyo has been engaged in flip chip technology with micro-bump for quite
some time with very successful results. More recently, it has demonstrated a 3D hybrid IC as a future PC-
card-type radio terminal for millimeter-wave frequencies. This structure consists of a dual-mode filter in a
dry-etching micromachined cavity, multilayered thin films, and flip-chip bonding of GaAs devices (see Fig.
5.16).




                       Fig. 5.16. Matsushita mm-wave system integration on a chip.

On the other hand, NTT has for some time proposed 3D MMIC with 6 metal layers and polyamide for
insulation (see Fig. 5.17). This has resulted in a comparable microstrip-line-based MMIC 1/3 to 1/20 in size,
for applications up to 65 GHz. NTT has built a U-band single-chip down converter based on this technology
with a conversion gain of 0 dB 1.5 dB and an image rejection ratio greater than 15 dB in a chip size of 1.78
mm  1.28 mm (see Fig. 5.18). The K-band Si 3D MMIC has an 0.70 mm  0.46 mm amplifier together
with an 0.46 mm  0.42 mm mixer (see Fig. 5.19).

             Tatsuo Itoh, Linda Katehi              45




     Fig. 5.17. NTT's concept on 3D MMIC.




Fig. 5.18. NTT U-band single-chip down converter.

                           5. Hardware for RF Front-End of Wireless Communication
46




                               Fig. 5.19. NTT K-band Si 3D MMIC examples.

The millimeter wave band is expected to be a frequency resource for the next generation's mobile
communication system and is aimed at achieving a high-frequency PC-card-type radio terminal. To realize
all the wireless functions including the antenna and the filter on a chip, a 3D hybrid IC structure is one of the
most effective solutions. Matsushita has recently developed a 3D millimeter-wave IC that uses silicon
micromachining. For the development of this IC, several technologies were used, including a dual mode
resonant filter, multi-layer thin-films on silicon, and flip-chip bonding for the GaAs devices. This circuit has
been utilized in a 25 GHz receiver down-converter and has an area of 11 mm2 including the built-in
micromachined filter.

With the progress of technology and the invention of the transistor, it became apparent that very small
transmission lines compatible with the planar technology of the newly discovered two- and three-terminal
devices are needed to effectively couple the power of microscopic devices and macroscopic systems. Circuit
miniaturization can be achieved by use of 3D integration where circuits are laid in all dimensions of the
space. This approach has been effectively used in designing microprocessors and has resulted in a dramatic
reduction of size and an unbelievable increase of speed. The next leap beyond the current state of the art
multichip modules (MCMs) is the development of a technology that can integrate high-frequency Si-based
active circuits, advanced micro-electromechanical (MEMS) devices, and micromachined components (e.g.,
filter/multiplexers) into one wafer. By employing 3D integration, significant reduction in mass (by a factor
of 10) in physical volume and in cost can be achieved easily.

New concepts in integrated conformal packaging have been introduced, leading the way for micromachining
to impact planar microwave circuits beyond the component level and into the system integration area.
Micromachining has the potential to revolutionize microwave devices by offering new techniques that can be
used to integrate entire systems onto a single IC. One scenario for total system integration calls for the use
of multiple layers to accomplish various system functions such as amplification, signal reception, down
conversion, and filtering. Micromachining offers the possibility of connecting these multiple layers together
vertically to achieve new levels of high density integration. This concept has already been applied to the

                                           Tatsuo Itoh, Linda Katehi                                         47

development of high frequency transmit modules and has demonstrated very high density integration along
with excellent RF circuit performance.


AMPLIFIERS

The amplifier is the key element in wireless hardware, be it a receiver or a transmitter. In the receiver, a low
noise receiver is needed to "screen" the desired signal out of background noise before the signal reaches the
down-converter. Although a futuristic direct conversion receiver is supposed to eliminate the conventional
heterodyne system, the increasing operating RF frequency makes it difficult for direct conversion to be
adopted. Good low noise reception can be accomplished routinely by the microwave industry with HEMT
technology.

The high-power final-stage (or output) amplifier is the key element in the transmitter. Since this amplifier is
the most power consuming, high efficiency amplifiers have drawn considerable research attention in the past
several years. On the other hand, for the spectrally efficient modulation scheme used in CDMA, amplifiers
will need to deal with a modulated RF carrier with a non-constant envelope, hence, amplifier linearity is
important. In order to obtain higher power-added efficiency, a higher class of amplifiers such as Class AB,
Class B or even Class C or switched mode Class E or F is often used. However, due to the V-I curves of
devices operated in these classes, the amplifier becomes nonlinear. Therefore, often high efficiency and high
linearity are contradictory objectives. There are several techniques to combat this problem.

One method tried at NEC is the use of adaptively controlled bias with a DC-DC converter for W-CDMA
applications (see Fig. 5.20). A similar approach has been demonstrated at the University of California at San
Diego to increase the average PAE while the amplifier is kept in Class A operation. Since the PAE is
extremely low in most instances of normal operation, the DC supply voltage is reduced in such instances to
reduce the DC power consumption.




                        Fig. 5.20. PAE improvement with DC-DC converter by NEC.

Somewhat more routine approaches are first to design a high PAE amplifier with a nonlinear mode and then
to provide a linearity-improvement scheme, such as feedback, feed-forward and predistortion. These
approaches tend to make the overall circuit configuration complex and the PAE lower. Matsushita Research

                          5. Hardware for RF Front-End of Wireless Communication
48

Institute Tokyo reported a new approach called the Hybrid Adaptive Predistortion method shown in Fig.
5.21.




                       Fig. 5.21. Hybrid adaptive predistortion method by Matsushita.

A recent trend is to cope with the linearity-PAE issue from the point of "transmitter unit" rather than a single
amplifier. The above examples include a control or signal processing circuit in the configuration.


ANTENNAS

The antenna is a constant subject of discussion, but as yet no perfect solution has been found for wireless
applications. There are many varied antennas from one-dimensional (dipole or monopole), two-dimensional
(inverted F and microstrip patches), and 3D (dielectric antennas). In addition, dishes and phased arrays are
used for base stations and satellite based communication. In this section, only the hardware aspect will be
reported while the software aspects, such as the smart antenna or software antenna, will be discussed in
Chapter 6 of this report. Also, as many efforts on the antennas are quite similar, the reports are intended to
provide the descriptions below only as typical examples.

NTT's multisector monopole Yagi-Uda (MS-MPYA) consists of two very low profile 12- and 6-sector units
for operation at 19 GHz. The 12-sector unit has a gain of 14 dB, and the 6-sector unit has a 10 dB gain.
These units are used for beam forming, as Fig. 5.22 shows.

                                          Tatsuo Itoh, Linda Katehi                                        49




                             Fig. 5.22. NTT's multi sector monopole Yagi-Uda.

NTT has developed rod-type small-sized antennas for 25 GHz applications. Microstrip antennas are printed
on panels within the rod, the beam radiating out from a cylindrical disk-like radome on top of it (Fig. 5.23).




                                 Fig. 5.23. NTT's rod type printed antenna.

At IMST, the effect of the human head on the antennas has been investigated extensively. It was found that
8 ~ 10 dB loss is caused by the human head in an experiment at 450 MHz. IMST tested the efficiency of
several antennas. IMST's helix antenna has 38% efficiency while its end-inductance antenna provided 84%.
A  wavelength patch has proven to be twice as efficient as the helix structure. IMST has also tried a
ceramic antenna for 0.9 and 1.9 GHz and have found that the bandwidth is too narrow.

Parabolic dishes still play an important role for wireless communication, especially for satellite-based
communication. NTT has developed several deployable on-board antennas (constructed of solid, wire-mesh)
that are inflatable. NTT's current non-inflatable mesh model consists of 7 modules, 10 meters in diameter,
and weighing about 80 kg. The target is 14-modules 14 to 15 meters in diameter and 120 kg in weight. This
technology was successfully transferred to NASDA (Japanese counterpart of NASA).


CONCLUDING REMARKS

Throughout this study and visits to selected sites in Europe and Japan and interactions with selected U.S.
industries, the WTEC panel recognized that hardware technologies for future wireless applications provide
substantial research opportunities on a worldwide scale. The following technological areas are either
emerging or evolving and are considered important for the future health of wireless technologies:
   devices and materials
    -    new materials and components (GaN, SiGe, MEMS, substrate materials, etc.)

                              5. Hardware for RF Front-End of Wireless Communication
50

     -   higher ft and fmax as well as higher linearity for active devices
     -   new 3D oriented process technologies
     -   higher performance passive components
     -   broadband antennas, higher gain antennas, low cost phased arrays
    front-end architecture
     -   amplifier linearization and efficiency
     -   interconnects and packaging
     -   mixed signal IC (baseband/RF)
     -   front-end architecture for software oriented radio
     -   RF aspects of smart antennas
     -   multifunction/reconfigurable devices/circuits/antennas
     -   MEMS RF components
    frequency of operation
     -   10, 35, 60, 77, and 95 GHz
    CAD
     -   global CAD (circuits, electromagnetics, devices, antennas, thermal, mechanical, packaging all
         inclusive and interactive)

Some specific additional features are as follows:

Amplifier efficiency and linearity are contradictory requirements. The typical approach is to design an
amplifier operated in a nonlinear mode and then provide schemes to improve linearity. The latter can be a
simple output power back-off or a more sophisticated feed-forward or predistortion technique. In any case,
not only good devices but also synergistic approaches are essential. It is important to optimize the amplifier
block or transmitter containing an amplifier and output circuits including antenna, or to make use of digital
technology for "signal processing" for the amplifier. Modulation format often dictates the choice of control.
For instance, a spectrally inefficient constant-envelope modulation is very resistive to nonlinear effects.
Combining digital techniques with an amplifier may lead to a form of "software" oriented radio.

A mixed signal IC may be a good ingredient for a futuristic one-chip radio or system-on-a-chip. But both
good devices and also low loss and high isolation interconnects are needed.

Software oriented radio has drawn much attention. However, often software issues and digital circuits issues
are emphasized while the RF front end is sometimes neglected. Therefore, front-end architecture should be
included in the studies for software radio.

Smart antennas are another example where the software and hardware collaborate well. Integrated antennas
alleviate some of the hardware difficulties associated with smart antennas. Also, reconfigurable circuits and
antennas should play important roles in developing the smart antenna.

Three-dimensional integration schemes are required to provide communication systems that are very small,
very low in weight and very low in cost without compromising performance. The use of heterogeneous
materials for the circuits and devices incorporated in the system may lead to unique solutions in integration
and packaging.

High-Q, low-loss passive devices are also needed for high performance. The development of RF MEMS
also provides new directions with the possibility of new functions and system architectures.

                                             Tatsuo Itoh, Linda Katehi                                       51

The above are some of the possible future directions of research. What should be emphasized is that future
research must require interdisciplinary approaches not only in terms of different hardware components but
also hardware and software.


TECHNOLOGY ASSESSMENT

It is always difficult to make a comparable assessment of the technical advances of several countries and
regions. The hardware technologies for wireless communication are no exception. In fact, due to the very
broad technical topics involved in this chapter, the challenge is even greater. Therefore, Table 5.1 provided
below is based on the quite subjective judgment of the authors of this chapter. The WTEC panel as a whole
does not disagree with this table.

                                                 Table 5.1
                               Wireless Technology Assessment for Hardware
                                                                 U.S.       Japan       Europe
         Millimeter Wave Circuits and Systems                     **        *****        *****
         Packaging/Interconnect                                 *****       ****          ***
         CAD                                                    *****        **           ***
                                                                                        *****1
         SiGe/Si                                                 ****        ***
         III-V                                                  *****       *****        ****
         GaN                                                     ****       ****          ***
         Antennas                                                ***        ****          ***
         Passive Components                                      ****       *****        ****
                                                                                         ****2
         Amplifier Technique                                    *****       ****
         MEMS/Micromachining                                     ****        ***          **
         1
             Germany only; 2 UK activities

The following six points pertain to the entries in Table 5.1:
1.   Millimeter Waves. Here, it is very clear that in terms of devices and MMICs, the United States is ahead
     of others, largely because of DARPA's successful MIMIC and MAFET projects. However, the U.S.
     entry here reflects expertise in millimeter wave circuits for non-military wireless applications. In Japan,
     government-led programs on 60 GHz wireless technology have been implemented, while in Europe a
     substantial effort has been expended mainly for automotive applications centered around 77 GHz.
2.   The United States has dominated CAD development and commercialization and it maintains an
     unchallenged position.
3.   In the area of SiGe, IBM is the leader. However, its circuit applications have lagged behind Daimler's
     effort, particularly in millimeter wave areas. In an effort to make the process technology available to
     others, IBM and Daimler process technologies are expected to benefit circuit design efforts funded by
     other organizations.
4.   GaN is still in its infancy in industrial applications. Most high performance devices devices are still at
     the research stage. It is interesting to note that the United States is leading in the RF (microwave) area,
     i.e., transistor development, while Japan's effort has mainly been in the area of optical devices. Cree in
     the United States and Nichiya in Japan have made excellent materials available.
5.   Antenna research has left much to be desired. In wireless communications, antenna research is meant to
     be different from the traditional in terms of the analysis, design, and characterization of antenna

                          5. Hardware for RF Front-End of Wireless Communication
52

     elements and/or phased arrays, from an electromagnetic point of view. What is needed is the
     development of an interdisciplinary research field useful for future wireless technologies. Examples are
     the integration of antennas with the RF front end, such as passive filters, MEMS devices, amplifiers, and
     even DSPs.
6.   In the area of passive components, the Japanese are slightly ahead due to their effort in high Q
     components led by Murata.
In closing, it should be emphasized that future research on wireless oriented hardware requires
interdisciplinary approaches not only between hardware and hardware but also between hardware and
software.

                                                                                                          53




                                              CHAPTER 6


                                        SMART ANTENNAS

                                            Jack H. Winters




INTRODUCTION

Throughout the world, including the United States, there is significant research and development on smart
antennas for wireless systems. This is because smart antennas have tremendous potential to enhance the
performance of future generation wireless systems as evidenced by the antennas' recent deployment in many
systems.

This chapter covers smart antenna technology, including software and system aspects. First the two basic
types of smart antennas, adaptive and phased arrays, are described and then their current use and proposed
use in future wireless systems is discussed. Then the key research issues that came up at the U.S. workshop
and at the various sites the WTEC panel visited are presented. Finally, conclusions are presented along with
the technology assessment of the U.S., European, and Japanese companies.


SMART ANTENNA DESCRIPTION

There are two basic types of smart antennas. As shown in Fig. 6.1, the first type is the phased array or
multibeam antenna, which consists of either a number of fixed beams with one beam turned on towards the
desired signal or a single beam (formed by phase adjustment only) that is steered toward the desired signal.
The other type is the adaptive antenna array as shown in Fig. 6.2, which is an array of multiple antenna
elements, with the received signals weighted and combined to maximize the desired signal to interference
plus noise power ratio. This essentially puts a main beam in the direction of the desired signal and nulls in
the direction of the interference.

A smart antenna is therefore a phased or adaptive array that adjusts to the environment. That is, for the
adaptive array, the beam pattern changes as the desired user and the interference move; and for the phased
array the beam is steered or different beams are selected as the desired user moves.

Nearly every company the WTEC panel visited is doing significant work in smart antennas. Indeed, some
companies placed strong emphasis on this research. In particular, researchers at NEC and NTT stated that
they felt that smart antenna technology was the most important technology for fourth generation cellular
systems. Researchers at Filtronics and other companies agreed that smart antenna technology was one of the
key technologies for fourth generation systems. The reasons appear below.

                                             6. Smart Antennas
54

        DESIRED SIGNAL




                                                                             SIGNAL OUTPUT




                                           Fig. 6.1. Phased array.


 DESIRED SIGNAL




                                                                               SIGNAL OUTPUT




     INTERFERENCE

                                                 BEAMFORMER WEIGHTS

                                          Fig. 6.2. Adaptive array.


FUTURE WIRELESS SYSTEM REQUIREMENTS

Future wireless systems generally may require higher data rates with better coverage for a wide variety of
users operating with a large variety of different systems. To achieve these goals, greater power, interference
suppression, and multipath mitigation are needed. As users operate at higher data rates, they need higher
power for adequate reliability. For higher bandwidths, higher carrier frequencies that have higher
propagation and circuit losses are needed. So some way to recover this power must be developed. In
addition, interference suppression is needed for higher capacities. Particularly as higher frequency reuse is
used to increase capacity, there will be more cochannel interference, which requires greater interference
suppression. Finally, multipath mitigation to have more reliable and robust communications is necessary.

                                               Jack H. Winters                                             55

SMART ANTENNA ADVANTAGES

Smart antennas can help systems meet these requirements in the following manner: First, both phased and
adaptive arrays provide increased power by providing higher gain for the desired signal. Phased arrays use
narrow pencil beams, particularly with a large number of antenna elements at higher frequencies, to provide
higher gain (power) in the direction of the desired signal. Adaptive arrays place a main beam in the direction
of the desired signal for an M-fold power gain with M antenna elements.

In terms of interference suppression, phased arrays reduce the probability of interference with the narrower
beam, and adaptive arrays adjust the beam pattern to suppress interference. For multipath mitigation, smart
antennas can provide diversity, of which there are three basic types: spatial, polarization, and angle (or
pattern) diversity. These appear in more detail below.


USE OF SMART ANTENNAS

From the site visits and U.S. company workshop, it appears that phased arrays and adaptive arrays are
considered and researched about equally. Although some companies studied only one type exclusively,
others work both on phased and adaptive arrays.

Phased arrays are mainly being studied for point-to-point wireless systems, e.g., for wireless local loops.
They are also being considered for macrocellular base stations. For example, in Europe there is work on
using 8-element phased arrays on GSM base stations. In Japan, there is work on using very large phased
arrays on satellites, as well as on satellite terminals such as on car tops.

Adaptive arrays are being studied for indoor systems, i.e., systems with wide angular spread where the
received signals arrive via widely separated paths where a phased array may not be useful in achieving gain.
Also they are being studied in microcells and in some cellular base stations. For example, currently in the
TDMA system ANSI-136 adaptive antenna algorithms have been widely deployed commercially in the
United States. Also adaptive arrays are being considered on cellular terminals where local scattering causes
wide angular spread.


KEY RESEARCH ISSUES

The site visits and the U.S. workshop raised several key research issues.

The first research issue is cost, including the cost of power. For example, at Philips, researchers noted that
50% of the power in the handset is in the RF electronics. Therefore, multiple antennas in the handset not
only increase the dollar cost of the handset, but also increase the power and thus decrease battery life.
Research to reduce the power that each of these antennas requires needs to be undertaken. Similarly, the
number of required receiver chains must be reduced because the RF electronics and the A/D converter
required with each antenna are expensive. One method being considered is a low-cost phased array. At
higher frequencies, some companies are considering using large phased arrays to create very narrow beams
to provide higher gain. But the issue is how to have, for example, hundreds of antenna elements and mass
produce them at a reasonable cost. Thus, cost is limiting the number of antenna elements that can be used.
Various solutions are being considered. For example, ATR is considering using optical beamforming for
large phased arrays. Another solution being considered is integrating the antennas onto the RF electronics
IC itself. Also, researchers at Ericsson are considering a limited introduction of smart antennas, because
their research has shown that using smart antennas at just a small portion of the base stations, e.g., those
having capacity problems or creating the most interference, can achieve most of the gain of complete
deployment. In particular, Ericcson's results show that deploying smart antennas at only 10% of the base
stations resulted in a 40% increase in capacity.

                                              6. Smart Antennas
56

The second key research issue is size. Large base station arrays are difficult to deploy for aesthetic reasons,
and multiple external antennas on terminals are generally not practical. For base stations, companies are
using dual polarization, but at the terminal some companies are researching putting antennas on the RF
electronics IC in an "antenna-less" terminal (since an external antenna is not present). However, issues of
gain and efficiency and the effect of hand placement on the terminal need further research.

The third issue is diversity, which, as discussed above, is needed for multipath mitigation. For diversity,
multiple antennas are needed on the base stations and/or terminals. As mentioned above there are three types
of diversity: spatial, polarization, and angle (pattern) diversity. Spatial diversityspatial separation of the
antennasis difficult on a small handset. Even though only a quarter wavelength separation is required for
low correlation of the multipath fading between antennas on a handset, it also is difficult for base stations
where the angular spread is small and large separation is required for low correlation. Spatial diversity is
even more difficult to achieve in point-to-point systems where a near line-of-sight exists between the
transmitter and receiver, and, further, at higher frequencies, sufficient spatial separation does not appear
feasible. This problem can be partially avoided by the use of polarization diversity, where both vertical and
horizontal polarizations are used to obtain dual diversity without spatial separation. For example, at Philips
and other companies, researchers are using dual polarization diversity on handsets. Others are studying and
implementing dual polarization on base station antennas. Polarization diversity provides only dual diversity,
though polarization diversity can be used in combination with other forms of diversity to obtain higher
orders of diversity.

Finally, companies are using angle diversity. That is, the signals from two or more beams (generally the
beams with the highest signal powers) are used to obtain diversity. But performance depends on the angular
spread. If the angular spread is small, then the received signal is mainly arriving on one beam and angle
diversity will not provide a significant diversity gain. Also, some companies are studying pattern diversity,
where antennas have different antenna patterns. In particular, researchers at Nokia are studying the use of
multiple antennas in the handset, where some of the antennas may be covered by the hand, and moving the
hand around changes the antenna pattern. These researchers believe that by adaptively combining the
signals from such antennas, perhaps only using those antennas not blocked by the hand or adjusting the
antenna impedance to compensate for hand placement, it may be possible to obtain much better performance
(including diversity) with multiple internal antennas as compared to an external antenna.

A fourth issue is signal tracking, i.e., determining the angle-of-arrival of the desired signal with phased
arrays to determine which beam to use and adjusting the weights with adaptive arrays to maximize the
desired signal-to-noise-plus-interference ratio in the output signal. At none of the sites the panel visited did
the researchers feel that signal processing power was a significant issue for tracking in future systems.
Instead, they felt that increases in signal processing power would permit new tracking algorithms to be
implemented without substantial consideration of the processing requirements. Researchers at Ericsson, for
example, noted that, although angle-of-arrival techniques for phased arrays use MUSIC or ESPRIT
algorithms in 2000, improvements are needed to make these algorithms more robust with angular spread and
to obtain higher resolution. For adaptive arrays, better subspace tracking methods are needed since higher
data rates will require longer temporal equalizers, which require longer training sequences and greater
overhead.

A fifth issue is spatial-temporal processing, i.e., equalization of intersymbol interference due to delay spread
at high data rates, with cochannel interference suppression. During the WTEC panel's European site visits it
was noted that better architectures are needed for spatial-temporal processing, as current architectures have
room for significant improvement. However, the use of OFDM is being considered for fourth generation
systems (as brought up during Japanese site visits), which may simplify spatial-temporal processing at high
data rates, but further research is needed. Also, space-time coding is an area of significant research,
primarily in the United States, but research on improved interference suppression and tracking with these
codes is needed. Finally, multiple transmit/receive antenna systems (referred to as multiple input multiple
output (MIMO) or BLAST for the Lucent Bell Labs version) are being touted mainly in the United States as

                                               Jack H. Winters                                              57

a means for achieving very high capacities in wireless systems. With MIMO, different signals are
transmitted from each antenna simultaneously in the same bandwidth and then are separated at the receiver,
thus increasing the potential to provide an M-fold increase in capacity without an increase in transmit power
or bandwidth. For example, Lucent has demonstrated 1.2 Mbps in a 30 kHz channel in an indoor
environment using 8 transmit and 12 receive antennas. To be useful in a wider variety of wireless systems,
however, research is needed to extend the technique to the outdoor environment, including determining the
multipath richness of this environment, which is required for the technique to work properly, and to the
cochannel interference environment of cellular systems.

A sixth issue involves putting the necessary hooks in the standards such that smart antenna technology can
be used effectively. In second generation cellular systems, ANSI-136 and IS-95, implementing smart
antennas had problems because the standards did not consider their use. In particular, ANSI-136 required a
continuous downlink signal to all three users in a frequency channel, which precludes the use of different
beams for each of these three users. In IS-95, there is a common downlink pilot, which also precludes the
use of different beams for each user, as all users need to see the pilot. For third generation systems, smart
antennas were taken into account in WCDMA, where downlink pilots are dedicated to each user, and
therefore smart antennas can be effectively used on the downlink. In the EDGE system, the continuous
downlink requirement is no longer present, but some signals from the base station still need to be broadcast
to all users. Thus, further research is needed to ensure that smart antennas can be effectively used in this
system. For fourth generation systems, therefore, smart antennas must be taken into account in standard
development. Specifically, any packet or multimedia access to all users, as well as pilots, must be
transmitted or done in such a way as to not preclude the use of smart antennas, if this technology is to be
used to its full benefit. Since these standards are international, research in this area needs to be done
globally.

The previous issue leads to the seventh and final issue: vertical integration or an interdisciplinary approach.
Research on smart antennas will require multiple factors/expertise to be considered--smart antennas cannot
be studied in isolation. This issue was brought up repeatedly during the WTEC site visits. As discussed
above, smart antennas must be considered in protocol development, i.e., expertise in both physical and media
access layers is required. Also, smart antennas need to be considered in combination with other techniques,
such as frequency hopping, power control, and adaptive channel assignment. Researchers at Nokia and
Philips noted that smart antennas need to be considered in combination with RF matching, particularly with
multiband antennas. At Nokia, the issue of adapting the antennas to hand position was noted. Ericsson has
studied the limited introduction of smart antennas with nonuniform traffic. Another issue was the interaction
when ad hoc networks are used. Furthermore, propagation measurements and channel modeling are needed
to determine the performance of smart antennas in specific environments. Issues of base station versus
terminal antenna (complexity) tradeoffs were also noted, as well as transmit diversity with space-time
coding. From the above issues, it seems important that smart antenna research be multidisciplinary.
However, few people have such a wide range of expertise, and it is often difficult for researchers with such
different expertise to work together effectively. Thus, even though the critical need for such research was
noted over and over again worldwide, there were few instances in any region where this was being done, or
even planned in the future, as this type of research is different from the general method used in the past.
Thus, this type of research appears to require a change of approach, but there was general agreement that the
companies that can do this will make the greatest progress in smart antennas.


CONCLUDING REMARKS

From the site visits in Europe and Japan and interactions with U.S. companies, it appears that the major
requirements for future wireless systems are higher data rates with better coverage to a large number of users
at a reasonable cost. To obtain these goals, higher signal-to-noise ratios (more power), interference
suppression, and multipath mitigation is needed. The smart antenna was universally recognized as a critical
component in meeting these requirements, but much research still needs to be done, as evidenced by the fact
that nearly all sites visited have a significant research effort in smart antennas. Research efforts are about

                                                6. Smart Antennas
58

equally divided between the two types of smart antennas (phased arrays and adaptive arrays), although the
emphasis varies among companies.

The WTEC study concludes that the major research issues for smart antennas are the following:
    cost (including power and electronics)
    size
    diversity
    tracking
    spatial-temporal processing
    hooks in international standards to include provisions for smart antennas
    vertical integration/interdisciplinary research
Of these, interdisciplinary research incorporating smart antennas was considered to be the key to the greatest
gains, but very little of this type of research is currently being conducted because of the difficulty of the
required interactions.

For future wireless systems to be viable, substantial research on smart antennas in the above areas will be
required, with emphasis on interdisciplinary approaches.


TECHNOLOGY ASSESSMENT

Smart antenna technology varies substantially among companies, and since many of these companies are
multinational, it is difficult to make a comparative assessment of the technology among regions. Nearly all
wireless companies visited, and therefore regions, have significant research in smart antennas, and thus
overall the current status of the regions in smart antennas appears to be about equal. However, the emphasis
of the research on phased or adaptive arrays varies by application. Specifically, Japanese companies
emphasize WCDMA and higher frequencies, and thus the major focus of their work is on phased arrays. On
the other hand, U.S. and European companies tend to emphasize lower frequencies (850 and 1900 MHz),
and TDMA systems (GSM, EDGE, ANSI-136) as well as WCDMA, and therefore focus on adaptive arrays
in addition to phased arrays. Thus, Japan leads in smart antenna research and technology for phased arrays,
particularly at higher frequencies (5 GHz and above), whereas the United States and Europe lead in adaptive
array research and technology (see Table 6.1).

                                                 Table 6.1
                                           Technology Comparison
                                                               U.S.        Japan       Europe
            Smart Antennas Overall                             *****       *****       *****
            Phased Arrays                                       ***        *****        ***
            Adaptive Arrays                                    *****        ***        *****

                                                                                                          59




                                              CHAPTER 7


                      HOLISTIC DESIGN OF WIRELESS SYSTEMS

                                               Ramesh Rao




INTRODUCTION

The phenomenal growth in mobile wireless communications combined with the equally impressive global
growth in Internet-related services and applications is poised to effect fundamental changes in all walks of
life. With this newfound success comes the need to cope with the demand for services that far exceeds early
projections. Much of this growth was fueled by early research funded by federal agencies and private
industry. Yet the need to reexamine and identify new areas will enable the next generation of innovations.
This report covers three related developments, software radios, energy and power management techniques,
and integrated approaches to system design.


SOFTWARE RADIOS

In contrast to conventional radios, software radios process signals mostly in the digital domain, making it
possible to put radio under software control. A number of companies in Japan and Europe described their
rationale for software radios and outlined areas of research that were viewed as critical for the development
of software radios. Alcatel, NTT, Daimler-Chrysler, NEC, Toshiba, Matsushita, Philips, Nokia, IMST all
reported ongoing research and development activities on software radios. U.S. companies that described
efforts in this regard included Hughes and Rockwell Collins. At the time of the WTEC study, most
companies viewed software radios as reconfigurable, multimodal, multichannel, or multiband devices. This
view does not call for radios that dynamically alter error control algorithms or modulation formats as a
function of the channel and traffic characteristics.

The development of a reconfigurable, multimodal, multichannel or multiband radio depends critically on
high resolution, high bandwidth, high dynamic range, A/D converters. Marcell Pelgrom at Philips has
forecast that the trend in higher resolution/bandwidth A/D converters will continue for another six to ten
years, with three orders of magnitude improvement still left. Besides A/D converters, Alcatel drew attention
to the need for frequency synthesizers and good integrable low noise amplifiers (LNAs) as additional
enablers for software radios.

Dr. Hori at NEC described an interesting application of the software radio concept by calling for studies of
systems in which reconfigurable radios are deployed only at base stations and not in the handsets. Base
station radios would then be expected to recognize the handset type and adjust themselves to the protocol
and system for which the terminal was designed. This would obviate the need for reconfigurable radios in
handsets and allow for smaller and cheaper handsets.

                                    7. Holistic Design of Wireless Systems
60

Bo Hedberg at Ericsson, speaking about the power efficiency of multicarrier power amplifiers, reinforced
Dr. Hori's view of the asymmetric deployment of software radios. Hedberg also concentrated on the base
station, because he thought that the software radio solution is very costly for terminals. The technology
needs to mature before it can be used at the terminals. Hedberg pointed out that power efficiency is
important, not just at the mobiles but also at base stations. Apparently, the air conditioning required to keep
the multi-carrier power amplifiers (MCPAs) cool at the base stations would increase the price significantly.
Hedberg estimates that half the cost of future base stations will be in the MCPA. Hedberg concluded that a
lot of research will be needed during the next several years to improve the MCPAs.

Assessment

State of the art

At the time of the WTEC study, the companies visited viewed software radios as enabling the production of
multimodal, multichannel or multiband terminals. The focus is on using a software reconfigurable terminal
to harmonize dissimilar standards in one lightweight, low cost package that can be mass produced and
reconfigured in software. The realization of this relatively modest objective requires additional progress on
(1) high resolution, high bandwidth, high dynamic range A/D converters, (2) frequency synthesizers, and (3)
better low noise amplifiers.

For a time, software radios are likely to be deployed only at base stations. In this scenario, the subscriber
would be shielded from the high cost, complexity, and power requirements of software radios. A primary
advantage of such an asymmetric deployment is the ability to support older generation handsets even as
service providers roll out newer generation services.

The base station's ability to sense and adjust to the terminal's capabilities (protocol, frequency band etc.)
could be used to create new competitive models for cellular services in which users, regardless of the type of
terminal they carry, can roam across competing systems. This would be in contrast to approaches in which
subscribers have to make a hard decision between competing providers that use incompatible air interfaces
and offer very good coverage limited to certain geographical regions. Such a model may help the cellular
industry as a whole to grow by offering more assured service to subscribers.

Once hardware requirements for the current generation of software radios have been met, the rationale for
software radios will evolve from lowering costs to enhancing performance at lower cost as the demand for
services starts to expand and saturates the available capacity. This objective will require more adaptive
software radios that will be capable of switching quite rapidly between modulation formats, error control
algorithms and other such features as a function of the channel, traffic and possibly battery characteristics.
The additional technical breakthroughs required will be in the area of software control of the underlying
hardware.

Deployment Trends

The task of assessing the relative status of U.S. companies in the global arena is fraught with limitations.
The need to provide global communications services provides a strong incentive for telecommunications
companies to operate as global enterprises. Therefore at a certain level, the distinction between U.S.,
European, and Japanese companies is quite artificial. Yet, in the context of communications, it is quite
instructive to examine the relative impact of regulatory developments, which do differ from nation to nation,
on technological needs.

In an article titled "Software radio technology: a European perspective," Tuttlebee (1999) argues that the
need for software radios is most acute in the United States where multiple second generation digital systems
compete in a market that has yet to be saturated. Such a market could be more efficiently served through the
use of software reconfigurable handsets. On the other hand, European standardization of GSM obviates the
need to develop software reconfigurable for multimodal, multi-standard handsets since the European

                                                 Ramesh Rao                                                61

multiband GSM allocations can be accommodated with modest enhancements at the RF end without
incorporating the full range of reconfigurations that software radios may be called upon to effect in the U.S.
market. Therefore, Tuttlebee claims that software radios are likely to emerge first in the United States and
then in Europe when there is a demand to support user roaming between GSM and third-generation UMTS
systems.

Publication Trends

To get a sense of the current state of the research activity, the WTEC panel analyzed publications on
software radios that have appeared in the recent literature, using the online INSPEC service, which tracks
"articles in over 4000 scholarly, journals, conference proceedings, books, reports, and dissertations in
physics, electrical engineering and electronics, computers and control, and information technology." Over
1400 publications on "software radio" appeared during the period 1995 to 1999almost one new
publication per day.

Of these 1400 publications,
   284 covered architecture
   235 covered RF elements
   178 covered protocols
   146 covered DSP algorithms
   127 covered antennas
   75 covered base stations
   20 covered batteries
   only 15 included any coverage of handsets.

With regard to author affiliations,
   about 40% listed U.S. institutions
   35% listed institutions in Germany, the United Kingdom, Italy, France, Finland, Sweden or the
    Netherlands
   5% listed Canadian institutions or others
   5% listed Japanese institutions

All but 90 of the 1400 publications were in English. Of the 90 non-English publications, 27 were in
Japanese.

These numbers suggest that current publications activity is largely in line with the software radio needs
communicated to the WTEC panelists: RF components, smart antennas, protocols, DSP algorithms and base
station deployment. U.S. leadership in the field appears to be consistent with Tuttlebee's assessment of the
critical need for early deployment of software radios in the United States. The extensive Japanese
development activities discovered by this panel during the site visits appear not to be reflected in
publications.

Summary Assessment

Factoring in all the information available at this time, the WTEC panel concluded that U.S., European, and
Japanese companies were on par with regard to software radio technology.

                                    7. Holistic Design of Wireless Systems
62

POWER AND ENERGY MANAGEMENT

Power and energy management issues came up in a variety of contexts including software radios.

Addressing the issue of power management in a broader context, Marcel Pelgrom at Philips noted the trend
towards higher energy per weight and size through the evolution of batteries from NiCd to Lithium-ion to
Lithium-polymer and beyond. Hans Hofstraat, also at Philips, discussed polymer batteries, which in 5-10
years could be widely deployed and reduce costs dramatically. However, Hofstraat, who passed around a
working polymer display driven by a polymer battery, believes that substantial research is still needed,
particularly multidisciplinary research.

The success of untethered, mobile communications depends critically on portable energy sources that enjoy a
long life. Longer battery life can be effected directly through the development of higher capacity cells but,
so far, advances in battery technology have failed to keep up with the rapid pace of developments in other
aspects of mobile communications. Thus, energy savings may more likely be found through more efficient
management of available battery energy.

Pelgrom claimed that the best research area for power management was better power management through
protocols. Pelgrom also observed that RF power consumption often dominates software power
consumption. He felt that long-term research should emphasize RF and packaging research and software
improvements that have a direct effect on RF power consumption. Nokia representatives pointed out that the
drivers of technologies in the future will be service and application protocols and not more capacity (as is the
current driver) and identified battery and energy management as one of the technologies needed to achieve
these applications. Mitsubishi Electric Corporation's overarching concern for reducing the size and weight
of handsets induced them to explore battery technologies to extend life or reduce weight. U.S. companies
that are interested in the topic include IBM, Hughes, Rockwell Collins, and Maxim.

Assessment

Development of higher capacity electrochemical cells has failed to keep pace with the demand. Therefore it
is desirable to develop energy efficient architectures, systems, protocols, algorithms, and circuits for the
efficient management of available battery energy.

Currently, the energy consumed in RF processing dominates digital processing. Technology areas in the
critical path include (1) RF and packaging advances, (2) software that reduces RF power consumption, (3)
energy efficient modulation formats and protocols, and (4) power efficient hardware-software co-design.
Low cost polymer batteries appear to be an innovative development on the battery technology side, but the
need for more extensive multidisciplinary research on the topic persists.

As networks reach deeper, penetrating home and commercial control applications, many simple non-
computing nodes will need to be networked. Such an approach is expected to result in new services and
applications. Current initiatives, such as Bluetooth, HomeRF, and sensor networks, are early precursors of
this trend. In sensor networks or any largely dormant segment of a network, battery powered nodes will be
mostly asleep and consequently consume most of their energy while asleep. Therefore research on ways to
reduce energy consumption in sleep modes is critical. This means that RF energy consumption is not the
only limiting factor.

The panel agreed that United States and European companies were on par with regard to their interest in
energy efficient system designs. The Japanese companies that the panel visited did not articulate any special
concern in this regard. Many of the leading suppliers of batteries for portable devices are currently Japanese.

                                                 Ramesh Rao                                                 63

INTEGRATED APPROACHES TO WIRELESS SYSTEM DESIGN

Over the years, the layering principle, which segments network functions and specifies standard interfaces
between layers, has served the networking community quite well. The standardization of functional
interactions between the layers has, to some extent, allowed developers to work independently of each other.
This has led to the development of multiple sources for protocols and new market-driven approaches to their
use and integration.

Three relatively recent phenomena have affected the way protocol stacks will have to be designed. First,
protocol stacks are being used in new ways. Two examples are "best effort" IP over ATM stacks that can
guarantee service quality and voice, which demands some quality guarantees, over best effort IP. Second,
concepts such as quality of service guarantees and energy conservation, which can be engineered in multiple
ways at various layers, are emerging. Finally, concepts like software controlled radios and active networks
that can be used to redefine networking functions on the fly are being developed. These three sets of
developments taken together stimulate the need for better understanding of the interaction between the
layers. IPSI, ATR, Mitsubishi, and NEC are working on these developments. Representatives of Hughes, a
U.S. company, described its interests in this topic as well.

Mitsubishi researchers reported that their concern for reducing the size and weight of hand sets compels the
exploration of cross layer opportunities for effecting efficient communications. At NEC, interest in
provisioning QoS, has led to a call for "definitions that work" and enhanced understanding of the functional
relationships between levels in order to effect system optimization. At NEC, Dr. Hori articulated the need
"to mix the software/system issues with hardware." For instance, NEC has an interest in a system on a chip
with integrated antennas.

The objectives of ATR's Adaptive QoS Management project are to develop adaptive ways in which network
parameters and resources are controlled in response to changing QoS demands in multimedia applications.
The focus at ATR was on controlling the compression and transmission parameters of video streams (bit-
rate, frame-rate, etc.) through negotiation among network agents that correspond to different user streams.
Eventually these negotiations will include allocation of additional network resources (such as buffer
memory, bandwidth, etc.). The investigators do realize that end-to-end QoS performance depends on the
lower-layer (link) QoS parameters and intend to include this coupling in their methods.

The visit at IPSI highlighted the issues in wireless networking that are often ignored by the wireless
community, namely the need to address the design of upper-layer protocols and their effects on link
operation. However, the visit verified that an integrated approach to networking that bridges the gaps among
layers is still needed, but not yet in place.

Assessment

A number of companies, especially those that were building prototypes, were keenly aware of the need to
develop a comprehensive understanding of design options regardless of the layer (of the system protocol
stack) that the function traditionally resides in. The most pressing problems identified included (1) "QoS
definitions that work," (2) better understanding of the functional relationships between levels, (3) interlayer
interactions, and (4) ways to mix software, systems, and hardware issues. More focused research is required
in order to understand the (1) effect of lower-layer (link) QoS characteristics on end-to-end QoS
performance and (2) the effect of upper-layer protocols on link operation. This research is necessary in order
to support more sophisticated negotiation between applications and networks.

From a larger perspective, the payoff from adopting integrated approaches may not be worth the cost of
deconstructing the layered approach to protocol design. Indeed, layering protocol stacks has served well in
the past. Yet, developments that motivate new research include the following: (1) the notion of a link layer
is much softer in the wireless environment than in a wire-line environment, (2) issues such as quality of
service guarantees and energy conservation can be engineered in multiple ways at various layers and, finally,

                                    7. Holistic Design of Wireless Systems
64

(3) new uses for protocol stacks. These developments require better understood interactions between the
layers of a protocol stack as well as between different protocol stacks. Research on this topic is likely to
further benefit from the availability of software controlled radios and the deployment of active networks that
can be used to redefine networking functions on the fly.

Japanese companies seemed to display the highest sensitivity to this issue. Perhaps this is consistent with
their early prototyping efforts. U.S. and European companies were on par with each other, but did not seem
as advanced as the Japanese.


SUMMARY

ATR, Alcatel, Daimler-Chrysler, Ericsson, IPSI, IMST, Matsushita, Mitsubishi, NEC, Nokia, NTT, Philips.
and Toshiba all reported activities in the areas of software radios, energy or power management, and
integrated approaches to wireless system design. The initial objectives described were technologically quite
challenging and were estimated to take at least five to 10 years to reach maturity and deserved to be nurtured
in the research community.

These objectives included development of (1) high performance A/D converters, (2) frequency synthesizers,
(3) low noise amplifiers, (4) low cost, long life batteries, (5) protocols that effect RF power economies, and
(6) techniques to support differentiated service qualities in a wireless environment. Scenarios for the
deployment of a new generation of systems based on these initial initiatives are already under careful study.

Many activities in wireless system design will benefit from substantial research and development in the area
of integrated approaches to wireless systems. Finally, these initial initiatives, which tend to have a hardware
focus, should lead to a second generation of integrated systems that will be driven by sophisticated protocols,
algorithms, and other software techniques that will harness the full power of the adaptive hardware to
produce new services and applications. Some thought should be given to exploring these possibilities.


REFERENCE

Tuttlebee, W.H.W. 1999. "Software radio technology: a European perspective." IEEE Communications 37 (2):118-
     123.

                                                                                                        65


                                           APPENDICES

APPENDIX A. PROFESSIONAL EXPERIENCE OF PANELISTS

Name:            Anthony Ephremides (Panel Chair)
Address:         Professor of Electrical Engineering & Institute for Systems Research
                 Department of Electrical Engineering
                 University of Maryland
                 College Park, MD 20742-3285
Anthony Ephremides received his B.S. degree from the National Technical University of Athens (1967) and
M.S. (1969) and Ph.D. (1971) degrees from Princeton University, all in electrical engineering. He has been
at the University of Maryland since 1971, and currently holds a joint appointment as Professor in the
Electrical Engineering Department and in the Institute of Systems Research (ISR). He is co-founder of the
NASA Center for Commercial Development of Space on Hybrid and Satellite Communications Networks
established in 1991 at Maryland as an offshoot of the ISR.

He was a Visiting Professor in 1978 at the National Technical University in Athens, Greece, and in 1979 at
the EECS Department of the University of California, Berkeley, and at INRIA, France. During 1985-1986
he was on leave at MIT and ETH in Zurich, Switzerland. He was the General Chairman of the 1986 IEEE
Conference on Decision and Control in Athens, Greece. He has also been the Director of the Fairchild
Scholars and Doctoral Fellows Program, an academic and research partnership program in Satellite
Communications between Fairchild Industries and the University of Maryland. He won the IEEE Donald E.
Fink Prize Paper Award (1992). He has been President of the Information Theory Society of the IEEE
(1987) and served on the Board of the IEEE (1989 and 1990).

Dr. Ephremides' interests are in the areas of communication theory, communication systems and networks,
queueing systems, signal processing, and satellite communications.

Name:            Tatsuo Itoh (Panel Vice-Chair)
Address:         Professor of Electrical Engineering
                 Department of Electrical Engineering
                 University of California, Los Angeles
                 405 Hilgard Avenue
                 Los Angeles, CA 90095-1594
Tatsuo Itoh received the Ph.D. degree in Electrical Engineering from the University of Illinois, Urbana, in
1969. He worked at the University of Illinois, Stanford Research Institute, University of Kentucky, AEG
Telefunken in Germany, and the University of Texas at Austin. In January 1991, he joined the University of
California, Los Angeles, as Professor of Electrical Engineering and holder of the TRW Endowed Chair in
Microwave and Millimeter Wave Electronics. He is currently Director of the Joint Services Electronics
Program (JSEP) and is also Director of the Multidisciplinary University Research Initiative (MURI) program
at UCLA. He was an Honorary Visiting Professor at Nanjing Institute of Technology, China, and at the
Japan Defense Academy. Since April 1994, he has been an Adjunct Research Officer for Communications
Research Laboratory, Ministry of Post and Telecommunication, Japan. He currently holds a Visiting
Professorship at the University of Leeds, United Kingdom, and is an External Examiner of the graduate
program of City University of Hong Kong. He has received a number of awards including the Shida Award
from the Ministry of Post and Telecommunication, Japan, and the 1998 Japan Microwave Prize.

Dr. Itoh is a Fellow of the IEEE, a member of the Institute of Electronics and Communication Engineers of
Japan, and Commissions B and D of USNC/URSI. He served as the Editor of IEEE Transactions on

                                Appendix A. Professional Experience of Panelists
66

Microwave Theory and Techniques for 1983-1985. He served on the Administrative Committee of IEEE
Microwave Theory and Techniques Society. He was President of the Microwave Theory and Techniques
Society in 1990. He was the Editor-in-Chief of IEEE Microwave and Guided Wave Letters from 1991
through 1994. He was elected as an Honorary Life Member of MTT Society in 1994. He was the Chairman
of USNC/URSI Commission D from 1988 to 1990, the Vice Chairman of Commission D of the International
URSI for 1991-93, and Chairman of the same Commission for 1993-1996. He is on the Long Range
Planning Committee of URSI. He serves on advisory boards and committees of a number of organizations
including the National Research Council and the Institute of Mobile and Satellite Communication, Germany.
He has over 750 publications and has advised 42 Ph.D.s.

Name:             Ray Pickholtz (Panel Vice-Chair)
Address:          Department of Electrical Engineering and Computer Science
                  Phillips Hall, 6th floor
                  George Washington University
                  Washington, DC 20052
Raymond L. Pickholtz is a professor and former chairman of the Department of Electrical Engineering and
Computer Science at The George Washington University. He received his Ph.D. in Electrical Engineering
from the Polytechnic Institute of Brooklyn in 1966. He was a researcher at RCA Laboratories and at ITT
Laboratories. He was on the faculty of the Polytechnic Institute of Brooklyn and of Brooklyn College. He
was a visiting professor at the Universite du Quebec and the University of California. He is a fellow of the
Institute of Electrical and Electronic Engineers (IEEE) and of the American Association for the
Advancement of Science (AAAS). He was an editor of the IEEE Transactions on Communications, and
guest editor for special issues on computer communications, military communications spread spectrum
systems and social impacts of technology. He is editor of the Telecommunication Series for Computer
Science Press. He has published scores of papers and holds six U.S. patents.

Dr. Pickholtz is President of Telecommunications Associates, a research and consulting firm specializing in
communication system disciplines. He was elected a member of the Cosmos Club and a fellow of the
Washington Academy of Sciences in 1986. In 1984, Dr. Pickholtz received the IEEE centennial medal. In
1987, he was elected as Vice President, and in 1990 and 1991 as President of the IEEE Communications
Society. He received the Donald W. McLellan Award in 1994. He was a visiting Erskine Fellow at the
University of Canterbury, Christchurch, NZ, 1997. He was awarded the IEEE Third Millenium Medal in
2000.

Name:             Magdy Iskander
Address:          Electrical Engineering Department
                  University of Utah
                  50 South Central Campus Dr., Room 3280
                  Salt Lake City, UT 84112
Magdy F. Iskander is Professor of Electrical Engineering at the University of Utah. From 1997-99 he had an
appointment as Program Director, Physical Foundation of Enabling Technologies, in the Electrical and
Communication Systems Division of the National Science Foundation. At NSF he formulated and directed a
"Wireless Technologies and Information Networks" initiative in the Engineering Directorate. This wireless
communications initiative resulted in funding over 29 projects in the microwave/millimeter wave devices,
RF micromachining and MEMS, propagation, and the antennas areas.

He has been with the University of Utah since 1977 and is presently the Director of the Center of Excellence
for Multimedia Education and Technology (formerly the NSF/IEEE Center for Electromagnetics Education).
In 1986, Dr. Iskander established the Engineering Clinic Program to attract industrial support for projects to
be performed by engineering students at the University of Utah. Since then, more than 95 projects have been
sponsored by 29 corporations from across the United States. The Clinic Program now has a large
endowment for scholarships and a professorial chair. From 1994-97 he was the Director of the Conceptual

                                Appendix A. Professional Experience of Panelists                           67

Learning of Science (CoLoS) USA Consortium, sponsored by the Hewlett-Packard Company, and has
eleven member universities from across the United States. He has received the Curtis W. McGraw ASEE
National Research Award for outstanding early achievements, the ASEE George Westinghouse National
Award for innovation in engineering education, and the 1992 Richard R. Stoddard Award from the IEEE
EMC Society. He spent sabbatical leaves at the Polytechnic University of New York; Ecole Superieure
D'Electricite, France; UCLA; the Harvey Mudd College, the Tokyo Institute of Technology, the Polytechnic
University of Catalanya, Spain, and at several universities in China, including Tsinghua University, Beijing,
South East University, Nanjing, Shanghai Jiaotong University, Suzhou University, and Yangzhou
University. He participated and presented the U.S. perspective in the special symposium on millimeter wave
technology sponsored by the Ministry of Post and Telecommunications in Japan, 1999. He is a Fellow of
IEEE and a member of the National Research Council Committee on Microwave Processing of Materials.

Dr. Iskander authored a textbook Electromagnetic Fields and Waves, published by Prentice Hall, 1992;
edited the CAEME Software Books, Vol. I, 1991, and Vol. II, 1994; and edited four other books on
Microwave Processing of Materials, all published by the Materials Research Society in 1990, 1992, 1994,
and 1996. He edited two special issues of the Journal of Microwave Power, one on "Electromagnetics and
Energy Applications," March 1983, and the other on "Electromagnetic Techniques in Medical Diagnosis and
Imaging," September 1983. Dr. Iskander also edited a special issue of the ACES Journal on computer-aided
electromagnetics education and the proceedings of both the 1995 and 1996 International Conference on
Simulation and Multimedia in Engineering Education. He was the General Chairman of the 1996 Frontiers
in Education Conference sponsored by the Computer and Education Societies of IEEE and the General Chair
for the IEEE Antennas and Propagation International Symposium and URSI meeting in the year 2000. He
has published over 160 papers in technical journals, has 8 patents, and made numerous presentations in
technical conferences. He was a Distinguished Lecturer for the Antennas and Propagation Society of IEEE
(1994-97) and during his tenure as a distinguished lecturer, he gave lectures in Brazil, France, Spain, China,
Japan, and a number of U.S. universities and IEEE chapters.

Dr. Iskander is the founding editor of the journal, Computer Applications in Engineering Education (CAE),
published by John Wiley & Sons Inc. This journal received the excellence in publishing award in 1993 in
the category of technology, science, and medicine. He is also an associate editor of the IEEE Transactions
on Antennas and Propagation (1995-98), an associate editor of the AP-S Magazine, and an elected member
of the IEEE AP-S AdCom from 1996-99. His research interests are in the area of computational
electromagnetics, antenna design and propagation models for wireless communications, microwave
processing of materials, biological effects of EM radiation, and the development of multimedia applications.

Name:             Linda Katehi
Address:          Professor of Electrical Engineering and Computer Science
                  University of Michigan
                  College of Engineering
                  1221 Beal Avenue
                  Ann Arbor, Michigan 48109-2102
Linda P.B. Katehi, Professor of EECS and Fellow of IEEE, received the B.S.E.E. degree from the National
Technical University of Athens, Greece, in 1977 and the M.S.E.E. and Ph.D. degrees from the University of
California, Los Angeles, in 1981 and 1984 respectively. In September 1984 she joined the faculty of the
EECS Department of the University of Michigan, Ann Arbor. Since then she has been interested in the
development and characterization (theoretical and experimental) of microwave, millimeter printed circuits,
the computer-aided design of VLSI interconnects, the development and characterization of micromachined
circuits for millimeter-wave and submillimeter-wave applications, and the development of low-loss lines for
terahertz-frequency applications. She has also been studying theoretically and experimentally various types
of uniplanar radiating structures for hybrid and monolithic circuits, as well as monolithic oscillator and
mixer designs.

                               Appendix A. Professional Experience of Panelists
68

She has been awarded the IEEE AP-S W. P. King (Best Paper Award for a Young Engineer) in 1984, the
IEEE AP-S S. A. Schelkunoff Award (Best Paper Award) in 1985, the NSF Presidential Young Investigator
Award and an URSI Young Scientist Fellowship in 1987, the Humboldt Research Award and The University
of Michigan Faculty Recognition Award in 1994, the IEEE MTT-S Microwave Prize in 1996, and the 1997
Best Paper Award from the International Society on Microelectronics and Advanced Packaging. She is a
Fellow of IEEE and a member of IEEE AP-S, MTT-S, Sigma XI, Hybrid Microelectronics, URSI
Commission D and member of AP-S ADCOM from 1992 to 1995. Also, Prof. Katehi is an Associate Editor
for the IEEE Transactions of the Microwave Theory and Techniques Society.

Name:            Ramesh Rao
Address:         Department of Electrical and Computer Engineering
                 University of California San Diego
                 9500 Gilman Dr., Mailcode 0407
                 La Jolla, CA 92093-0407
Ramesh R. Rao was born in Sindri, India, in 1958. He received his Honours Bachelor's degree in Electrical
and Electronics Engineering from the University of Madras in 1980. He did his graduate work at the
University of Maryland, College Park, receiving the M.S. degree in 1982 and the Ph.D. degree in 1984.
Since then he has been on the faculty of the department of Electrical and Computer Engineering at the
University of California, San Diego. He is a member of the industry-sponsored UCSD Center for Wireless
Communications.

His research interests include architectures, protocols, and performance analysis of wireless, wireline, and
photonic networks for integrated multi-media services.

He has been a reviewer for a number of journals, conferences, funding agencies and book publishers. He is
the founding Web Editor of the Information Theory Society web site. He served as the Proceedings Chair
of the 1994 International Parallel Processing Symposium and the 1995 International Conference on High
Performance Computing. He served as the Technical Program Chair of the 1997 International Conference
on Universal Personal Communications and is the guest editor for a special issue of the Wireless Network
Journal and a special issue of the Journal of Selected Areas in Communication on Multi-media Network
Radios. He is the Editor for Packet Multiple Access of the IEEE Transactions on Communications and is a
member of the Editorial Board of the ACM/Baltzer Wireless Network Journal as well as the IEEE Network
Journal. He is a member of the Board of Governors of the IEEE Information Theory Society.

Name:            Wayne Stark
Address:         Professor of Electrical Engineering and Computer Science
                 University of Michigan
                 College of Engineering
                 4227 EECS Building, 1301 Beal,
                 Ann Arbor, MI 48109-2122
Wayne Stark received the B.S. (with highest honors), M.S., and Ph.D. degrees in electrical engineering from
the University of Illinois, Urbana, in 1978, 1979, and 1982 respectively. Since September 1982 he has been
a faculty member in the Department of Electrical Engineering and Computer Science at the University of
Michigan, Ann Arbor, where he is currently Professor. From 1984-1989 he was Editor for Communication
Theory of the IEEE Transactions on Communication in the area of Spread-Spectrum Communications. He
was involved in the planning and organization of the 1986 International Symposium on Information Theory,
which was held in Ann Arbor, Michigan. He was selected by the NSF as a 1985 Presidential Young
Investigator. He is principal investigator of an Army Research Office Multidisciplinary University Research
Initiative (MURI) project on Low Energy Mobile Communications. His research interests are in the areas of
coding and communication theory, especially for spread-spectrum and wireless communication networks.
Dr. Stark is a member of Eta Kappa Nu, Phi Kappa Phi and Tau Beta Pi, and a Fellow of the IEEE.

                                Appendix A. Professional Experience of Panelists                           69

Name:             Jack Winters
Address:          Technology Leader, Wireless Systems Research Department
                  AT&T - Research
                  Newman Springs Laboratory
                  Room 4-148, 100 Schulz Drive
                  Red Bank, NJ 07701
Jack H. Winters received his B.S.E.E. degree from the University of Cincinnati, Cincinnati, Ohio, in 1977
and M.S. and Ph.D. degrees in Electrical Engineering from the Ohio State University, Columbus, in 1978
and 1981, respectively. Since 1981 he has been with AT&T Bell Laboratories and now AT&T Labs 
Research, where he is in the Wireless Systems Research Department. He has studied signal processing
techniques for increasing the capacity and reducing signal distortion in fiber optic, mobile radio, and indoor
radio systems and is currently studying adaptive arrays and equalization for indoor and mobile radio.

Dr. Winters is a member of Sigma Xi and a Fellow of the IEEE.

70


APPENDIX B. PROFESSIONAL EXPERIENCE OF OTHER TEAM MEMBERS

Name:             Joanne H. Maurice
Address:          Air Force Office of Scientific Research
                  Asian Office of Aerospace Research and Development
                  U.S. address: Unit 45002, APO AP 96337-5002
                  Japan address: 7-23-17 Roppongi, Minato-ku, Tokyo 106-0032
Ms. Maurice is a liaison scientist for the Air Force Office of Scientific Research's Asian Office of Aerospace
Research and Development (AFOSR/AOARD) in Tokyo, Japan. Her responsibilities include assessments of
emerging technologies in Asia and the Pacific Rim countries, including Australia and India, and encouraging
foreign and U.S. Air Force scientists working on leading edge technology to actively pursue research
collaborations through sponsorship of lectures, conferences, and exchange visits. Her career with the U.S.
Air Force began in 1988 at the Photonics Center at the AFRL Rome Research Site, formerly Rome
Laboratory (RL), in central New York State. There, she conducted in-house applied engineering research for
the development of C4I photonics technology for processing, storing, and transmitting information. While a
member of RL, she served as a visiting scientist at the Cornell University Nanofabrication Facility (CNF),
using the resources there to fabricate novel photonic device structures for optical interconnect applications.
She has authored several publications related to her in-house photonics work. She received her M.S. (1994
in Electrical Engineering) from Syracuse University. Her B.S. (1988, Engineering Physics) is from MIT.
She has received several scientific achievement awards and performance awards.

Name:             Nader Moayeri
Address:          Manager
                  Wireless Communications Technologies Group
                  National Institute of Standards and Technology
                  100 Bureau Drive, Stop 8920
                  Gaithersburg, MD 20899-8920
Nader Moayeri was born in Hamadan, Iran, on August 31, 1956. He studied electrical engineering at Sharif
University of Technology, Tehran, Iran, from 1974 to 1978. He received the MSEE, MSCICE, and Ph.D. in
electrical engineering-systems from the University of Michigan, Ann Arbor, 1980, 1981, and 1986,
respectively.

From 1986 to 1994, he was with the Department of Electrical and Computer Engineering at Rutgers, the
University of New Jersey. From 1994 to 1997, he was with the Imaging Technology Department at Hewlett-
Packard Laboratories, Palo Alto, California. Since September 1997, he has been with the National Institute
of Standards and Technology, Gaithersburg, Maryland. At NIST, he is the Manager of the Wireless
Communications Technologies Group, which he organized during 1997-98. Dr. Moayeri's research interests
include data compression, mobile radio communications, information theory, and routing and flow control in
data networks. He has served the Princeton/Central Jersey Section of the IEEE in various capacities, among
which was Section Chair (1992-93) and founder and first Chairman (1989-93) of the Information Theory
Chapter. He was a Co-chairman of the Joint DIMACS/IEEE Workshop on Coding and Quantization, held at
Rutgers University in October 1992.

Name:             Hiroshi Morishita
Address:          HMI Corporation
                  Matsudo Paresu 1002, 35-2 Koyama
                  Matsudo 271-0093, Japan.
Mr. Morishita, President, HMI Corporation, specializes in ultra-micro manipulation technology for MEMS
(MicroElectroMechanical Systems). He founded HMI Corporation in 1991 to commercialize his ultra-micro

                         Appendix B. Professional Experience of Other Team Members                       71

manipulator system. He extended his interest and business to the field of archaeological excavating
machines and to a new robot manipulator system to help bed-ridden persons. In 1994, he became a
consultant to WTEC concerning its study tours in Japan. He graduated from the University of Tokyo (BA,
MA, mechanical engineering) and is in the final stage of preparing his doctoral thesis. He was a visiting
researcher in the Mechanical Engineering Department in 1992 and 1993, and at RCAST (Research Center
for Advanced Science and Technology) of the University of Tokyo in 1994 and 1995.

Name:            Leo Young
Address:         ODDR&E
                 4015 Wilson Blvd., Suite 209
                 Arlington, VA 22203
Dr. Young obtained degrees in mathematics and in physics from Cambridge University in England, and a
doctorate in electrical engineering from the Johns Hopkins University in Baltimore, Maryland. He is a
member of Sigma Xi, a Fellow of the American Association for the Advancement of Science (AAAS), and a
Life Fellow of the Institute of Electrical and Electronics Engineers (IEEE). He has held senior positions at
Westinghouse, Stanford Research Institute, and the U.S. Naval Research Laboratory; he retired from the
Pentagon as Director for Research in 1994 and now consults for that office. He has served on many
government, industry, and university advisory boards, and was the first chairman of the NSF Engineering
Advisory Committee. Dr. Young has authored, co-authored or edited 14 books and over 100 papers, and he
holds 20 patents. He has received numerous awards from IEEE and received an honorary doctorate from the
Johns Hopkins University. He served as President of the IEEE Microwave Society, and later as IEEE
President and Chairman of the Board. He is a Foreign Member of the Royal Academy of Engineering of the
United Kingdom. His current interests focus on RF components for wireless communications

72


APPENDIX C. SITE REPORTS--EUROPE

Site:                   Alcatel
                        54 rue La Boetie
                        75008 Paris
                        France

Date Visited:           29 April 1999

WTEC Attendees:         R. Pickholtz (report author), M. Iskander, J. Winters, L. Young

                        Vinod Kumar
Hosts:
                        Alistar Urie
                        Alain Bravo
                        Martial Guillaume
                        Elie Bejjani
                        Hikmet Sari
                        Gert Bostelmann

SYNOPSIS

This site is the Corporate Headquarters for Alcatel (Alcatel Telecom plus Business and Corporate). The new
organization for Alcatel is a matrix of services and business divisions that operate worldwide. Some
highlights of this matrix, as they directly impact or are impacted by wireless technology include:
Services        Networking              Access Systems            Enterprise and Consumer
Network         Radio                   - Internet Access         Professional and Consumer
Architecture    Communications          - Transmission Systems
Division        Division                - Space Products

Alcatel operates a Corporate Research Center (CRC) with 700-800 people, an IP group of 200 persons, and a
Technical Strategy and Standardization program (40 people).
The CRC supports scientific/technical projects for short to medium (2-5 years) terms plus some long-term
(8-10 years) projects to prepare for the future. Publication and professional society activity is viewed
favorably. CRC is spread over many sites: France (6), Spain, Belgium, Germany, and the United States.
Currently there are eight technical departments: software, energy, optical, radio, space, network access,
network architecture, and private networks.

M. Guillaume gave a thoughtful and informative talk on both the business prospects of wireless and the
emergence/convergence of technologies through 2004. He expects voice traffic to increase by a factor of 2
but non-voice is a major trend that may overtake it. European initiatives to provide Internet services include
General Packet Radio Service (GPRS), Wireless Application Protocol (WAP), and the consideration of
portable operating systems (OS) such as CE, Palm Pilot, Symbian and Java+. The general feeling is that
many companies will contend for dominance of portable digital devices via the operating system, as this will
drive applications and services. The OS will also play a large role in the services delivered by wireless.

Alcatel is firmly established in the circuit switched (CS) business but is also moving rapidly to provide
packet switched (PS) IP Networks. Alcatel is prepared to offer wireless mobile service via both modes. It
was not clear that there would be a strong convergence in the next few years.

                                      Appendix C. Site Reports--Europe                                      73

Alcatel is also very much involved in satellite communications and has built remarkable technology for radar
and signal processing, mostly for military applications. These technologies, however, are quite suitable for
commercial adaptation to wireless communications.

In particular, Alcatel developed several working active antenna array systems with beamforming in the
K-band, 12.5  12.75 MHz only using both amplitude and phase control of 48 subarrays with 3 x 48 control
elements.

T/R beam steering antennas with over 6,000 elements have been designed.

H. Sari presented a number of ideas for improving the physical layer performance that are being studied
including, but not limited to, turbo codes, multicarrier transmission, improved CDMA plus, informally, a
number of theoretical "hot topics" and their likelihood of implementation.

Such emphasis was given to bring the digital processing closer to the antenna by incorporating the low noise
amplifiers (LNAs) upconverter and L.O. into a single chip. The bottlenecks for full software radio are high
dynamic range, wideband, accurate A/D converter, frequency synthesizers, and good LNAs that are
integratable.

Elie Bejjani predicted that wireless might replace the last mile (local loop) even for high speed applications.
There was discussion of "mobile dedicated HTML" for encompassing the unique character of mobile links
and possible novel applications. Emphasis was placed on PS with IP/ATM or direct ATM Wireless.

Focus topics for research included turbo codes, CDMA optimization, multicarrier improvements (crest
factor, synchronization), better, faster power control, study of dynamic effects of power control and
optimization, tradeoffs between diversity and array processing gain, and novel techniques for non-coherent
modulation/demodulation.

There was considerable discussion about the four-way wireless/wired/CS/PS standards and the ultimate
convergence of these parts. Additional discussions included software radio and the European vs. North
American approach.


SPECIFIC TOPICS

Alcatel personnel made a series of organized presentations. In addition there were several annual review
reports, which convey the sense of direction of work being done at Alcatel in all areas of
telecommunications. Wireless communications is one component of this. The distinct impression conveyed
was that Alcatel considers wireless to be one component, albeit a very important one, of a vast, emerging
global network.

The main thrust of the meeting with Alcatel was systems. The hosts did not address specific hardware
devices such as microwave components, physical antennas, or semiconductor technology. However, Alcatel
is involved in these areas.

                                      Appendix C. Site Reports--Europe
74

Site:                 Centro Studi E Laboratori Telecomunicazioni (CSELT)
                      10148 Torino
                      Via G. Reiss Romoli, 274
                      Italy

Date Visited:         30 April 1999

WTEC Attendees:       N. Moayeri (report author), A. Ephremides, R. Pickholtz, W. Stark, L. Young

Hosts:                Enrico Buracchini, Mobile Services and Radio, Radio Systems, Techniques and Radio
                           Methodologies
                      Giovanni Colombo, Mobile Services and Radio, Head, Mobile Services
                      Gaetano Francesco Cazzatello, Mobile Services and Radio, Propagation, Antennas
                      Claudio Mattiello, Mobile Services and Radio, Propagation, Modeling and
                           Simulations
                      Agostino Moncalvo, Mobile Services and Radio, Head, Satellites and Microwave
                           Radio Relay Links
                      Valerio Palestini, Mobile Services and Radio, Head, Radio Systems
                      Federico Tosco, Head, Mobile Services and Radio

BACKGROUND

CSELT has 1,223 employees, of whom about 826 work in technical areas and have university degrees. The
salaries at CSELT are competitive with those offered by the private industry. CSELT is the research arm of
Telecom Italia, which provides 75% of CSELT's budget. CSELT's 1997 revenues and investments were
$163 million and $28 million, respectively. If Telecom Italy merges with Deutsche Telekom, there will be
only one research center. The mobile activities will be at CSELT, and the German side will handle the
network aspects. CSELT collaborates closely with CNET in France. There are also collaborations with
British Telecom.

Telecom Italia has 126,381 employees and $26.677 billion of revenues. It spends $589 million on research.
(The last three numbers are from 1996.)

G.F. Cazzatello gave a presentation on smart antennas. Linear power amplifiers are important for the proper
operation of switched beam antennas. Another type of smart antenna is the angle diversity antenna system.
In this type of system, the output from several narrow-beam antennas is compared with the output of a wide-
angle antenna, and the best signal is selected. That signal is the output of the GSM receiver connected to one
of the narrow-beam antennas. The output is the soft decision output of the Viterbi equalizer and before the
Viterbi decoding. Ray Pickholtx, a WTEC study team member, commented that one should be able to do
better with maximal ratio combining rather than simply selecting one of the signals.

The next type of smart antenna discussed was the adaptive phase array antenna. This antenna tries to reduce
interference by adaptively introducing nulls. In the case of adaptive beamformers in the GSM system, there
is a 26-bit midamble in each 148-bit frame. This information is used by the adaptation algorithm.

C. Mattiello gave a presentation entitled, "3G Systems Modeling." He emphasized propagation channel
modeling in a micro-cellular structure. Typical height of the base station is 3-5 meters. A database of the
geographic area is constructed based on aerial photography. This results in a map with a resolution of one
meter. The height information for buildings is also incorporated in these maps. The information is then used
to create a color-coded map of field strengths in the geographic area. Mattiello showed a profile of delay
spreads as a function of spatial position at 1,800 MHz. This was done with a fixed transmitter and a moving
receiver in a corridor (perhaps a street). The delay profile in an indoor car-parking garage looked like a mess
with many peaks. He went over ray tracing, which is very expensive, and ray launching, which is more

                                    Appendix C. Site Reports--Europe                                   75

tractable but not very accurate. The latter computation was done with 360 rays, one per degree. He showed
a comparison between actual signal strength measurements with the ray launching method and with another
method taking diffractions into account.

E. Buracchini gave a presentation on software radios. Software radios are not likely to be implemented or
used until 2005 - 2010, even if everything goes right. The main obstacles are the need for high resolution
ADC/DACs and the complexity of the processing. There was a discussion on how software radios should be
introduced. Should there be a common standard, such as Windows CE or Java OS, or should there be
proprietary platforms for each provider? What would be best for the manufacturers and users? Most
participants felt that a common platform would be superior for all parties involved.

G. Colombo gave a presentation entitled "Network Architecture for 3G Systems." GPRS should be
introduced in the beginning of 2000 for GSM. The problem of macro-diversity in CDMA systems was
addressed. In a wideband CDMA system, a mobile might be communicating with a few base stations during
soft handover. An important issue is how the higher levels of the network should handle the situation. One
possibility is to change the core control point in the network. He talked about the use of ATM Adaption
Layers to handle both circuit-switched and IP type of connections on an ATM network.

                                      Appendix C. Site Reports--Europe
76

Site:                 Daimler-Chrysler Research Center, Ulm
                      Wilhelm-Runge Str. 11
                      89081 Ulm (Donau)
                      Germany

Date Visited:         27 April 1999

WTEC Attendees:       L. Katehi (report author), T. Itoh, D. Friday, R. Pickholtz

Hosts:                Johann-Friederich Luy
                      Karl-Michael Aldinger
                      Holger Meinel
                      Oskar Krumpholz
                      Karl Strohm

BACKGROUND

The Ulm research facility has a total of 450 researchers and support personnel and is situated 3 km outside
Ulm. The whole lab occupies 23,000 sq. ft of clean space including clean facilities from 10,000, to 1, as
show in Fig. C.1.




                            Fig. C.1. Daimler-Chrysler Research Center, Ulm.

The Daimler-Chrysler research labs were reorganized recently. The company follows an R&D 3-vector
model in which technological competence, customers, and research programs constitute the three axes of a
multi-dimensional research space. The research activities in the Daimler-Chrysler Research Center in Ulm
cover five core technology fields:
1.   drive systems
2.   autonomous systems
3.   production and materials
4.   mechatronics
5.   products and sales

                                    Appendix C. Site Reports--Europe                                    77

Among the applications that can possibly be covered under these technology areas, emphasis is given to the
following:
   communicationsto stay in touch while on the move, available at anytime, anywhere
   surveillancemonitoring relevant information to enable adequate actions
   navigation and detectionfeel safe and secure about a position, permit personal navigation on a global
    level
In each of these areas, Daimler-Chrysler and DASA are developing products that address a number of
customer needs as shown in Fig. C.2. The wireless communications applications and customer products
cover a wide range of high frequencies from 800 MHz to 77 GHz and require high operation speeds from a
fraction of a Gbps to tens of Gbps. Research efforts in these application areas include development of
software radio, digital receivers, micro-millimeter wave mobile communications and radar systems,
contactless sensors, and antenna technology for digital beam-forming for high density TV. In high
frequency device development, the company is focusing on the development of III-V based 2.5 GHz and 5
GHz mobile phones. However a serious effort is being undertaken to develop SiGe based devices to
accomplish high density and multi-functionality.


       Sys e sope ateat high fre ue c e dueto lowatmos he icatte uation w ndow
          tm      r             q nis                 pr        n        i    s
       and/or dueto bandw dth de ands
                         i      m
          GHz
          Gbit/s            Communic tion
                                    a                   Surve llanc
                                                             i     e              Navigation

             1            Global mobilephone                                   Global pos tioning
                                                                                         i
                         Digital c rdle sphone
                                  o    s
             2          Wire e sloc Are ne w rk
                            ls     .    a to

             5                                          Road pric ng
                                                                  i
                              Hype -LAN
                                  r
                                                       We the radar
                                                           ar
                                                    Synth. Ape ture radar
                                                              r                Sate lite navigation
                                                                                   l
           10                 TV s te lite
                                  al
                           Broadband s te lite
                                       al                 Robotic                De e c radar
                                                                                   fne
                                                      Earth obs rvation
                                                               e
                                                     Airport s rve llanc
                                                              ui        e        Landing radar
            20
                                Minilinks              Indus ry s ns rs
                                                            t eo               Obs ac ew rning
                                                                                  tl a
                          Digital optic l c mm.
                                       ao
                                                       Traffic s ns rs
                                                                eo            Collis on avoidanc
                                                                                    i           e
                          Mobile broadb. s rvic
                                           ee
            50
                                                     Environme t c ntrol
                                                               no
                                                     Pre ie road s ns ng
                                                        vw         ei             Flight radar
           100
                        Fig. C.2. Technical trends to meet future society demands.

The strength of this center is the development of high-frequency device, circuit and antenna design for the
above described communication systems. The research groups have demonstrated world records in InP
HEMTS technology (see Fig. C.3).

In addition to InP, Daimler-Chrysler has seriously invested in GaN technology and has demonstrated
microwave high power modules with fmax above 50 GHz. Effort is presently underway to incorporate this
technology into imaging radars operating at millimeter-wave frequencies.

                                        Appendix C. Site Reports--Europe
78


                        0.5                            InP-based HFETs offer performance advantages in:
         L (m)                  0.25 T     0.20 T
          G
                                                       Higher speed  higher operation frequencies
                                                                       same performance at smaller chip size
       Gm(mS/mm)        600       700       900
                                                                                               lower MMIC-costs
                                                       Lower noise figures
       IDsmax
            (mA/mm)     500       500       600           lowest noise figure of any three terminal device
                                                          more sensitive receivers, new/cheaper system concepts
         fT   (GHz)     55        120       130
                                                       Lower Bias points
                                                                      reduced power consumption
        fmax(GHz)       150       250       >300
                                                       Improved power added efficiency at mm-wave frequencies
                                                                      reduced power consumption
     NF (dB)/f(GHz) 1.1 / @18 0.6 / @18 2.3 / @60
      mi n
                                                       Zero-volt bias mixer diodes possible
     G ss
      a (dB)/f(GHz)   13 / @18 11 / @18 6/ @60
                                                                      reduced LO-power required




                          Fig. C.3. Overview of Daimler-Benz InP-based HEMTs.

To achieve high integration and multifunction capability, Daimler-Chrysler is pursuing the development of
SiGe-Si microwave and millimeter wave integrated circuits (SiGeSIMMWIC) for range sensors, speed
control, etc. In addition to integration and performance, the company expects low cost to be the driver in
using this technology in customer products for wireless applications. Such applications include
communications and sensing/navigation. Comparisons made between InP-, GaN-, and SiGe-based products
show superior cost potential in the SiGe technology (see Fig. 5.11, p. 40) and indicate device superiority due
to very low 1/f noise and low phase noise: SiGe transit-time diodes in self-oscillating mixers have
demonstrated frequency stability with sub-harmonic locking. Free running has demonstrated about -60
dBc/Hz at 100 kHz from the carrier and with phase locking about 90 dBc/Hz at 100 kHz from the carrier.
In this circuit technology, CPW has been chosen as the interconnect medium due to its superiority to thin
film microstrip and its associated need of a via hole technology. CPW solves a number of problems but
requires an air-bridge technology, which however is easier to make due to its requirements of wafer-surface
and not wafer-bulk fabrication.

Daimler-Chrysler is the leader in SiGe technology and has demonstrated performance records in SiGe HBT
as shown in Fig. 5.12 (p. 40). A number of SiGe applications include Ka-Band CPW oscillator HBTs, a 77
GHz near-field sensor with SiGe Schottky diodes, and a 77 GHz closing velocity sensor. While SiGe
technology is progressing fast, a number of processing issues still need to be resolved. To alleviate some of
these issues, passivation of the device by a Si3N4 has been adopted. Low temperature, low power cpw-based
HBT structures are routinely demonstrated (20 mW at 47 GHz) (6 emitter figure device). At present,
research is focused on the development of phase resonant devices with fmax=300 GHz achieved by quantum-
well injection.

Daimler-Chrysler is inserting this technology into customer products via an extensive product development
effort performed in the "Microwave Factory" owned by DASA. This facility called the "M5-Service Center"
(Microwave and Millimeter-Wave Module Engineering and Manufacturing Services) enables the
development of products based on the research of the various D-C research centers. This center has 84 staff
members, occupies 10,000 sq. ft. of dedicated space, and has a DM 17 million measurement facility in
addition to the fabrication facilities. Sensors such as SatCom, MobilCom, Cruise control at 77 GHz, and
LMDS at 28 GHz, as well as a 24 GHz radar designed to measure material properties for application in steel

                                      Appendix C. Site Reports--Europe                                     79

production, have been produced. Other products include a 58 GHz point-to-point link in hybrid formulation
with GaAs MMICs using bonding wires for connection to MMIC chips. This facility has been sole supplier
to many communications companies (including Nokia) and focuses on defense/space products for guidance
and communications, with 60-70% in defense and 30-40% in commercial communications. The antenna
group of DASA does all antenna measurements.

In communications technology, Daimler-Chrysler is investing in telematics, advanced media and services,
information technology, and software technology. Efforts are focused on application specific solutions for a
variety of services including vehicle IT systems, personalized security systems, vehicle integration antennas,
vehicle networks, multi-agent systems, and object oriented techniques. Other applications include the
following:
   Internet to the car by using flat panel displays
   Motiv: telemetric project to develop a traffic routing system using GSM (0.9-2.5 GHz)/DAB (1.8)
   Game: Global Automotive Mobile Entertainment
   error recording via Radio LAN
   digital radio via a short wave communication system (2-9.6 kB/s)
   mobile broadband communication systems (complementary of UMTS)
   150 Mbps up to 5 km range wireless and mobile based on ATM
   ATM mobile (see above)
   fast train communications (38 GHz), among others
In addition to the above, Daimler-Chrysler is developing optical back planes for board-to-board
interconnection. The back planes interconnect high-performance signal processors for modular avionics that
require 1-8 Gbps and require serial buses instead of parallel busses. The backplanes are designed in ring or
star configurations. Back planes offer advantages over space transmission since they provide a vibration-
free solution. Free-space transmission and optical guidance through a polymer wave-guide give a 3 dB loss
with an axial tolerance > 2mm and lateral tolerance better than +-500 micros. Power budgets are very
critical, and wave guide attenuation better than a few dB/m is required to make designs successful. Polymer
optical wave-guides with 1-3 dB/m attenuation in the short wave are used and are coupled through mirrors
for good efficiency and low spillover. This technology has been demonstrated in a 1 Gb application. The
length of the back plane was 26 cm and exhibited 3.5 dB loss. Demonstrated system margin was
approximately 10 dB. Planar optical wave-guide crossing loss =0.7 dB, and line loss can be improved by
anti-reflection coating. Total loss can be as low as 2.5 dB. An issue that needs to be addressed is the
collection of particles on the transitions of the optical wave-guide or on the lenses. Vibration tests have
shown excellent potential and aging tests of the low-loss wave-guide (200 hours) have indicated no increase
in losses. Possible applications may provide 2.5 Gbps, while interconnection lengths up to 19 inches have
been achieved.

                                       Appendix C. Site Reports--Europe
80

Site:                  Ericsson Radio Systems AB
                       Torshamnsgatan 21-23
                       164 80 Stockholm
                       Sweden

Date Visited:          26 April 1999

WTEC Attendees:        N. Moayeri (report author), A. Ephremides, M. Iskander, R. Rao, W. Stark, J. Winters,
                           L. Young

Hosts:                 Soren Anderson, Manager, Antenna Systems and Propagation Research, Ericsson
                            Research, Corporate Unit
                       Hakan Eriksson, Vice President and Gen. Manager, Ericsson Research, Corporate Unit
                       Hakan Eriksson, Manager, Radio Access Research, Terminals
                       Ulf Forssen, Director, System and Technology, Business & Product Line Management
                            TDMA Systems
                       Bjorn Gudmundson, Research Director, Radio Systems
                       Bo Hedberg, Senior Expert, Radio Technology Research
                       Johan Skold, Expert, Digital Radio Access in Cellular Systems, Radio Access and
                            Antenna Systems Research
                       Anders Khullar, Ericsson, Lund

BACKGROUND

The panel visited the Radio Systems division of Ericsson, where most of the R&D work related to wireless
communications is carried out. Ericsson, however, is much more than this and is active in many other areas
of electrical engineering and information technology. The most important and active area of wireless
communications from a commercial point of view, as the 21st century approaches, is the development of 3G
wireless communication systems. The International Telecommunication Union (ITU) is vigorously pursuing
the development of the International Mobile Telecommunication 2000 (IMT-2000) standard for 3G wireless
systems, which it intended to complete by the end of 1999.

Ericsson is a powerful voice and a major player within the European Telecommunication Standards Institute
(ETSI), which is the sponsor of the W-CDMA proposal for the IMT-2000 standard. Ericsson has had the
largest share and contribution in the development of Bluetooth, which is a short radio for wireless LAN type
applications in the 2.4 GHz ISM band. To be more precise, Bluetooth is a cable replacement device that
connects all personal computing and communications devices to each other in a wireless fashion. In fact, it
is to be used even in future home appliances if all goes well with its development by Ericsson, IBM, Intel,
Nokia, and Toshiba.

The first presentation was given by Hakan Eriksson, Vice President and General Manager of Ericsson
Research, about the areas Ericsson is involved with and some facts about research in areas of high
technology in Sweden. He said that universities are now more involved in industrial research in Sweden.
They work closely with Ericsson. He then talked about the distinctions between 3G and 4G wireless
systems. In case of 3G wireless, the spectrum had been clearly specified from the outset. It is much harder
to define 4G wireless, because the spectrum has not been defined. He showed a slide of different wireless
systems on a bit rate vs. mobility (fixed, local area, wide area) plane. He talked about three scenarios for
voice-over IP.

The first scenario is what we have today. He also compared several scenarios (cases of sending various
types of data) in traditional ways and over a wireless network. He showed that wireless made more sense
than the traditional ways in a number of cases, i.e., it was cheaper, at least with the present pricing structure
we have today. He also showed that for email, wireless is a lot better, but for images and video, traditional

                                     Appendix C. Site Reports--Europe                                      81

ways are still better. He stated that it would be very unlikely that people would watch video on a small
pocket-sized terminal. However, such terminals would be good for voice, email, postcards, and music.

Bjorn Gudmundson explained that research at Ericsson has a shorter horizon than the 10 years that WTEC
study team member Tony Ephremides mentioned in his talk. Gudmundson added that the Ericsson staff
present at the meeting all worked on radio aspects, and that they would not be the best people to answer
network-related questions such as whether ATM or IP was the best alternative for sending voice and some
other types of data over the network. There are some experts in those areas at Ericsson, but they were not
present at the meeting. Regarding ACTS, FRAMES, and other such programs administered by the EC,
Gudmundson said that he believed that those programs were not very efficient, as there is a lot of paperwork
and overhead. On the positive side, these programs represent a framework for industry to work closer with
universities all over Europe. But then Ericsson has had good informal relationships with the universities for
many years.

Bo Hedberg gave a talk on multi-standard, multi-carrier, wideband radios. Multi-carrier radios have to
handle much larger dynamic ranges. That means stricter requirements on the A/D, D/A, and the multi-
carrier power amplifier (MCPA). Some part of their architecture can be controlled digitally and through
software. The RF front-end generally is not controllable. He said that power efficiency was important not
just at the mobiles but also at the base stations. Otherwise, they would have to use large fans to keep the
MCPAs cool, and that would increase the price quite a bit. The dynamic range in multi-standard, multi-
carrier, wideband radios would increase by about 20 dB over present systems (GSM). Half the cost of future
base stations will be in the MCPA. The present price for this component is about $100 per watt of average
RF output power.

Hedberg felt that a lot of research was needed during the next several years to improve the MCPAs. He
concentrated on the base station, because he thought the problem was harder for the terminal stations. He
felt that the software radio solution was very costly for terminals. The technology needs to mature before it
can be used at terminals. Note that the multi-carrier requirements at the terminals are much looser than in
the base stations. The 1 microsecond frequency-hopping rate discussed refers to the radio at the base station.
It is not possible to have such a high rate at the terminals. The present rate used at base stations, based on
analog synthesizer techniques, is one frequency hop per millisecond.

Soren Anderson gave a talk entitled, "Adaptive Antennas in Wireless Systems." He outlined possible
alternatives for smart antennas and space-time processing. He presented a general radio architecture for
taking advantage of these concepts. As always, the interesting question is how much benefit would one get
for the cost? In cellular systems, the downlink is usually the bottleneck due to interference. So, when it
comes to smart antennas and space-time processing, it is best to concentrate on the downlink. In an FDD
system, for example, one knows a lot more about the characteristics of fading in the uplink direction than in
the downlink direction. In a TDD system, one has a different situation.

Anderson then talked about the potential benefits of smart antennas in GSM downlink transmission. He
showed a 5-6 dB improvement at the mobiles. Yet another example shows that with sector antennas the
quality drops very quickly in comparison with smart antennas. The measure of quality was probability of
frame error rate being less than 2%. Note that power control is independent of what was discussed here. PC
has its own gains. Also note that to get the maximum benefit of smart antennas in a heterogeneous network,
one needs to have good estimates of the traffic distribution in the cell.

Bjorn Gudmundson talked about radio access technologies. He said that mobile Internet access will be the
main driver for wireless systems in the future. As far as fourth generation (4G) wireless is concerned, it is
not clear whether it should provide much better coverage-bitrate performance or somehow combine in an
architecturally sound fashion a variety of systems such as LMDS, Bluetooth, WLAN, IMT-2000, mobile
satellite systems, etc. He then concentrated on the evolution of cellular systems by showing 2G, 2.5G, and
3G systems. He put the EDGE system in the 3G category. He talked about the structure of dedicated
physical channels in W-CDMA. He said that it was harder to use smart antennas in IS-95, because it

                                    Appendix C. Site Reports--Europe
82

handled the pilot bits differently than in W-CDMA. He then compared GSM and EDGE. In GSM the
modulation is GMSK, which transmits one bit per symbol. EDGE uses 8 PSK. The concept of adaptive
coding and modulation helps EDGE adapt itself to the link quality. He went over major differences between
W-CDMA and CDMA2000. He then talked about certain indoor systems (WLAN, Hiperlan-II, and
Bluetooth). The distinction between Bluetooth and HomeRF was questioned. Gudmundson did not have
any comments about HomeRF.

Ulf Forssen talked about EDGE and how it related to GSM and W-CDMA. It is, of course, an extension of
GSM. He discussed the relationships between EDGE, GSM, and TDMA/IS-136, as well as the tradeoff
between spectrum efficiency and average throughputs. In summary, EDGE offers a way to harmonize GSM
and IS-136. It has been approved by ETSI and UWCC and has been submitted to ITU. It will provide
global roaming for a very large user base.

Johan Skold talked about W-CDMA. He went over a number of features of the UTRA system.

Hakan Eriksson, Manager of Radio Access Research, gave a presentation on mobile terminals. He talked
about their present terminals and future directions. He also talked about some possible applications. In
addition, he talked about Bluetooth and the Wireless Application Platform (WAP) Forum. Symbian
(Ericsson, Nokia, Motorola, and Psion), which is an open architecture, allowing different software
developers to develop new applications for these terminals, was also discussed.

Anders Khullar's talk was titled "GSM Terminal Evolution." He discussed positioning systems and their
impact on mobile price. He covered TOA, OTD, and GPS. He is with Ericsson, Lund.

                                      Appendix C. Site Reports--Europe                                      83

Site:                 Filtronic PLC
                      The Waterfront
                      Salts Mill Road
                      Saltaire, Shipley
                      West Yorkshire BD18 3TT
                      United Kingdom

Date Visited:         Friday, April 30, 1999

WTEC Attendees:       D. Friday (report author), M. Iskander, T. Itoh, R. Rao, J. Winters

Hosts:                Professor J. David Rhodes, Chairman, Filtronic plc
                      Professor Christopher M. Snowden, Director of Technology, Filtronic plc
                      Professor Peter Clarricoats, Chairman Technology Advisory Board, Filtronic plc and,
                           Chairman, Defense Scientific Advisory Council, Ministry of Defense, UK
                      Eric G. Hawthorn, Engineering Director, Filtronic Comtek
                      Dr. Richard G. Ranson, Director, Subsystems Engineering, Filtronic Comtek
                      Alan Needle, Managing Director, Filtronic Comtek

Additional unidentified participants came and went throughout the day

FILTRONIC PLC, THE COMPANY

Filtronic was founded in 1977 and is a public limited company (plc) incorporated in England and Wales.
Professor Rhodes has been Executive Chairman and Chief Executive Officer since its founding. The
company is multinational, with several subsidiaries in Europe, Australia, and North America, and it is a
world leader in the design and manufacture of a broad range of products for communication across the radio-
frequency (RF) spectrum. These products include microwave and millimeter-wave devices, components and
subsystems for wireless communications, cellular handsets, components for hardwired networks such as
cable TV and high-speed Internet access, and electronic warfare systems. The company claims to be able to
supply products at any frequency, for every transmission standard and every modulation system in the world.
Its products primarily receive, transmit, filter, and amplify RF signals. Markets are categorized in four broad
areas. These markets, and the percentages of Filtronic's business in each of these areas in 1998, are as
follows: Wireless Infrastructure (55.8%), Cellular Handset (26.4%), Electronic Warfare (17.1%), and Cable
(0.7%). In 1998, the company had sales of 181.1 million ($295.3 million), almost all its wireless business
being mobile cellular. The focus in this report will be on the commercial wireless communications aspects
of the business, the first two categories and 82.2% of Filtronic's business.

In 1989, Filtronic bought Philcom Microwave, the first of its U.S. interests. This gave Filtronic a
technological edge with which to move, more rapidly, into the base station and mobile communications
market. In 1994, the company went public on the London stock exchange. The commercial communications
market is Filtronic's primary customer base, and national-defense agencies form a second customer base.
Filtronic supplies the latter with electronic warfare equipment and systems. The electronic warfare (EW)
part of the business remains privately owned and provides access to the U.S. defense market. The advanced
defense technology, especially in communications, also provides Filtronic with a critical edge for
commercial applications. In the United Kingdom, Filtronic has facilities in Shipley (the Corporate
Headquarters and WTEC visit site), Stewarton, East Kilbride, Wolverhampton, and Milton Keynes. The
U.K. activities include the design and manufacture of wireless and cable products, EW products, and ceramic
and ferrite wireless components. Filtronic has facilities (LK Products) in Kempele and Oulu, Finland, for the
design and manufacture of access and subscriber products. In its Brisbane, Australia, facilities Filtronic
designs and manufactures wireless and EW products. In the United States, the company has facilities in

                                      Appendix C. Site Reports--Europe
84

Salisbury Md., Merrimack, N.H., Santa Clara, Calif., and Natick, Mass. The more recent of these U.S.
acquisitions include Litton Solid State, Sage Laboratories, and subsidiaries.

Primary commercial customers are the leading international original equipment manufacturers (OEMs).
Filtronic plc employs approximately 3000 employees worldwide, including 250 engineers, of whom 10 %
have Ph.D.s. Filtronic refers to its worldwide holdings and resources as the "Filtronic Group." The Filtronic
strategic goal is to become the pre-eminent supplier of RF, microwave, and millimetric products.


FILTRONIC PLC, THE TECHNICAL PROGRAMS

Materials

Filtronic management, early on, saw materials as critical to competitiveness in wireless technology and
acquired a U.K. ceramic and ferrite manufacturing company. The main materials-technology roadmap is
focused on requirements for ceramic resonators. The fundamental challenge is price vs. performance for the
components produced with these materials. Good performance means lower-losses (higher Q), higher
dielectric constants (size reduction), and invariance of the material properties under changes in temperature.
Present low-cost ceramic resonators have Q-values ranging from 15,000 to 20,000, and are based on
ceramics with dielectric constants ranging from 35 to 45. Current, high-end ceramics have dielectric
constants from 45 to 55 and achieve Q-values of 30,000. Filtronic representatives stated that one of the
targets was a resonator, at 1.96 GHz, with a loaded Q of 50,000. Their roadmap predicted high-Q resonators
with dielectric constants ranging from 70 to 200 in 5 years.

Base Stations, Amplifiers, and Filters

Base station technology is another key element in Filtronic's corporate planning and roadmapping efforts,
with amplifier and filter performance the key issues. Dual-mode conductor loaded ceramic and high-Q
combline filters are mid-priced and also mid performance ( unloaded Qs of 5,000 to 8,000). TE (0,1,d) and
dual-mode TE (0,1,d) filters achieve unloaded Qs of 50,000 but at twice the price. There is a need to drop
the price of these components. Filtronic is leveraging the Sage acquisition for base station coupler
technology. The wireline technology is low cost and yields high performance among competing
technologies. Ferrite components and their manufacturing processes for planar circulators is another base
station technology the company is roadmapping.

Filtronic sees three viable options for base station filter technology for 3G: GPRS, EDGE, and W-CDMA.
One option is modular systems including integrated systems, micro-controllers, and highly linear power
amplifiers. The second option is TE (0,1,d) ceramics technology including multimode, helical, and other
designs. The third option comprises improved versions of more traditional machined combline filters.
Filtronic's dual-mode conductor-loaded ceramic technology has enabled a one-half size reduction. The
insertion loss is 0.5 to 1 dB for a typical base station. These devices have a very good Q (not given) and are
the result of an 18-month development period combining both ceramics technology and metalization
technology.

Filtronic does not have any projects for using high temperature superconductors (HTS) for base station
filters. They cited the nonlinearities and reliability as factors that make HTS technology less attractive as a
product line. Filtronic also believes that advances in conventional technology have marginalized the
performance gains of HTS hardware.

3G hardware will require improved linear amplifier technology and better efficiency, particularly for
wideband CDMA. Software radio is doablethere should be no problems at the lower frequencies.
Transceivers need to be cost effective. There is a need for distributed switching systems in base stations.
One objective is to make a significant advancement (details unavailable) in Class A amplifier performance
by September 2000. Filtronic is taking an integrated approach, without close project management, and

                                      Appendix C. Site Reports--Europe                                      85

researchers believe they have a key advantagespecial expertise and proprietary software for integration of
complex filters.

Base Station Antennas

Prof. Rhodes discussed the issue of the higher power (approximately 20 dB) needed for base stations to have
the same coverage for high data rate systems (such as EDGE) as for current mobile radio systems. He
discussed the use of adaptive antennas, in particular, pencil beam phased arrays on the uplink and downlink
at base stations to provide a higher gain. Key research issues were seen to be multiband phased array
antennas for base stations, along with filters and efficient and linear power amplifiers. Tower top electronics
were also seen as an issue. The use of terminal adaptive arrays was not felt to be practical (because of the
expense), as was the use of higher frequencies (because of diversity issues with point-to-point links). DSP
power was not felt to be a concern. Other Filtronic comments regarding base-station antennas were "we
can't get away from pencil beams from the base stations," and "multibeam RF is absolutely necessary and
difficult."

Fixed Broadband Wireless

Comments concerning LMDS implied Filtronic does not see a wide market for this. Researchers said that
LMDS in the United Kingdom was licensed in the frequency band 40.5 to 43.5 GHz. Experiments
performed led them to the conclusion that propagation reliability will be poor with the moist and rainy
weather typical of the United Kingdom. They said that point-to-multipoint architectures were not likely to
succeed and that perhaps multipoint to multipoint would be a better architecture  a dynamic network in
which every user would be a possible relay-node. They didn't see such an architecture being acceptable in
the more privacy and security conscious United States. They also feel that most demands can be met with
existing bands, and envision 1% of the market for LMDS, mostly wireless local loops. They also said one of
their subsidiaries (Radiant Networks plc ) had a 25 Mbps wireless technology and that LMDS is not right
from either standpoint.

Wireless Handsets

The purchase of LK Products has extended Filtronic's expertise and its market to include handsets.
Customers now include Nokia, Ericsson, Siemens, Bosch, AT&T, Hyundai, etc. Clearly, the only directions
here are to make the handsets smaller, less costly, and more multifunctional and to improve their
performance. Since handsets are simply housings for the real technology, the only solutions are in advances
in the components discussed elsewhere. Filters are a key component and in addition to the ceramic
technology discussed under "Materials," surface acoustic wave (SAW) filters are showing promise. Helical
filters, traditionally used in handsets, will likely drop out of use as ceramics and SAW improve. The one
exception is the handset antenna and integration of the antenna with its housing as well as the RF front end.
Improved integration was seen as a key issue here. The cellular air interface also needs attention,
particularly the antenna technology, the effects of hand placement, and the user-body effects on antenna
performance. Additional comments were "3G specifications, such as 2 Mbps are political issues," "GSM
will be driven by power requirements," and "multi-antenna handsets will be essential."

Semiconductors

Filtronic does not use HEMTs but developed a capability (by acquisition) for fabricating pHEMTs. Their
pHEMTs have very high linearity, TOI up to 20 dB above P-sub-I. Researchers developed the capability for
producing MMICs up through mm-waves. Filtronic now has MBE and E-Beam capability, several class
1000 and Class 100 Clean Rooms, and GaAs, InP, and YIG fabrication technology. Filtronic sees
semiconductors as one of the most critical technologies, where it needs to maintain cutting-edge capabilities
in design and manufacture, in order to remain competitive. The hosts had an interesting observation on
competing semiconductor technologies particularly SiGe: They see the frequencies for Si technology being
pushed much higher and the costs for GaAs being pushed down. The end result is that SiGe technology will

                                      Appendix C. Site Reports--Europe
86

lose its perceived advantage and drop out as an alternative for wireless.        The company has no SiGe
fabrication capabilities.

General Comments on Wireless Bands: Low Frequencies

Everyone will go to the limits to use these frequencies as much as possible. Some applications assumed to
be the domain of higher frequencies will be done in the future at lower frequencies, and industry will
develop much more competence at exploiting these frequencies.

High Frequencies

Receiving much attention at present, but the ultimate applications and implementations will have to sort
themselves out. Many technical (hardware) challenges remain before this technology is competitive. Most
demands can be met in the existing band.


SUMMARY/CONCLUSIONS

Filtronic Wireless Vision, Research Recommendations

Chairman Rhodes stated in his overview that the company's technological niche requires that it operate in
one of the world's most highly competitive markets. Very rapid advances in technology characterize this
market and its industries. Filtronic, he said, competes on the basis of cost, quality, performance, and
manufacturing and delivery deadlines. All R&D and corporate acquisitions are directed toward advancing
the technology, the expertise, and the production capability necessary to stay even with or ahead of the
competition for the next major procurement contracts. If Filtronic falls behind, it will be adversely affected,
and even its OEM customers may become competitors if they can manufacture equivalent products at less
cost. Filtronic has a long-term planning process and showed us for perusal (but did not provide) a
proprietary copy of their strategic plans, the Filtronic corporate roadmap. Our perspective however, was that
the technology requirements forecasting process was critically driven by the need to make the next logical
improvement in existing devices, components, and subsystems. The rationale was clear. If the company's
product is not competitive in the next few rounds of procurement competition, the long-term future will be
irrelevant. Although this essential aspect of the planning process was in the forefront, it was balanced by a
longer term vision that encompassed new technologies, experimentation, and prediction of customers' needs
through the year 2005. Director of Technology Snowden stated that the horizon was only 5 years out, due to
the rapid evolution of markets and technology. William Smith, who spoke regarding the manufacturing
operations, said the basic mode of operation is "get the call today, deliver the product tomorrow." A typical
product may go from specifications to a volume-manufactured product in less than eight weeks. This is
clearly a very difficult environment in which to do long-term technology forecasting. However, Filtronic did
develop and provide insights into the next steps in wireless hardware improvements.

The Filtronic management left the WTEC study team with its vision of the five key research topics that, over
the next five years, will have an important impact on future wireless communications technology products.
The key topics are the following:
    systems perspective: systems architecture, hardware/software-integration/optimization
    smart antenna systems
    power amplifiers for both handsets and base stations
    filters (including materials)
    digital signal processing to enable more efficient use of hardware
Filtronic hosts stated that performance is the bottom line and given the success and rapid growth of Filtronic
plc since its inception, this vision may not be too far off.

                                      Appendix C. Site Reports--Europe                                     87

Site:                 GMD FOKUS
                      German National Research Center for Information Technology,
                      Research Institute for Open Communication Systems
                      Kaiserin-Augusta-Allee 31
                      D-10589 Berlin
                      Germany
                      http://saturn.fokus.gmd.de/fokus/

Date Visited:         29 April 1999

WTEC Attendees:       R. Rao (report author), A. Ephremides, N. Moayeri

Hosts:                Eckhard Moeller, Head of Competence Center PLATIN
                      Mihai Mateescu, Head of MOBRA
                      Christian Schuler, member of MOBRA

SUMMARY

Forschungsinstitut fr Offene Kommunikationssysteme (FOKUS) or the Research Institute for Open
Communication Systems was formally established in 1988, but its roots can be traced to the much older
Hahn-Meitner-Institut in Berlin. It had then and continues to have an institutional focus on providing
"information at any time, at any place, in any form, and according to personal preferences." GMD FOKUS
undertakes research and pre-product development work on a variety of communications and computing
initiatives.

FOKUS draws 30% of its support from the German government. The remaining 70% comes from
companies like Deutsche Telekom and Textronix in Germany, Hitachi and NEC in Japan, the Racal Data
Group in the United States, from E.U. programs like ACTS and ESPRIT, and from national R&D programs
such as the German Research Network (DFN).

FOKUS takes part in a number of technological developments through R&D projects, management and
development of international test beds, software and hardware prototypes, and product development.
FOKUS is an active contributor to main standardization bodies such as OMG, EURESCOM, TINA-C, ATM
Forum, TMF, IETF, ETSI, ISO, and ITU-T, and is active, as well, in education at universities (in particular
the Technical University of Berlin) and other organizations. FOKUS has experience in developing working
demos, and an essential part of its success in this regard comes from extensive industry involvement not only
in donating equipment but also in setup and testing.

The organizational structure at GMD FOKUS and the funding mechanisms pursued exposes researchers to
market forces. Although this exacts a price in the management of projects and recruitment and retention,
research personnel seem to be engaged in relevant work.

About 20% of its 185 employees are permanent and the rest are hired for terms not exceeding five years.
The permanent staff provides leadership and continuity. The temporary staff is hired for specific projects
and the duration of their appointments are directly tied to the duration of the projects. This is viewed as a
source of some difficulty in hiring and retention.

Discussions with key senior personnel spanned issues pertaining to network centric and user centric support
for mobility, hybrid fiber radios, scheduling for the wireless channel, error control, fourth generation
systems, cellular IP, and software radios.

Drs. Mateescu and Moeller, the WTEC panel's gracious hosts at GMD FOKUS, believe that competition is
key to driving down the costs of access as well as the provision of proxy services to untethered mobile users.

                                     Appendix C. Site Reports--Europe
88

As far as mobility support was concerned, they saw particular merit in two architectures/technologies:
architectures involving smart network resident agents that shadow mobile users and serve up appropriately
reformatted information to low cost terminals and architectures where the mobile exercised more control and
relied on network infrastructure primarily as a low cost transport medium.

Dr. Mateescu believes that communication is about information exchange. Large databases will be used to
store this information, and therefore he sees high bandwidth optical networks as a key element of the overall
communication infrastructure. In this context, an ongoing project on Hybrid Fibre Radio at GMD FOKUS
was described to the panelists. The system incorporates passive devices that convert optical signals to RF
and vice versa. The architecture allows for the deployment of many low cost antenna/converter subsystems
that are linked to a more central base station. EURESCOM (www.eurescom.de), a pan-European institute
for strategic studies in telecommunications, has an interest in understanding how this and other such
technologies would affect the business of European telephone service providers.

Although research driven by market forces has its appeal, Dr. Mateescu indicated that a new hurdle in
securing commitment of market actors for long-term projects was not the fear of failure but the fear that the
work might become irrelevant in today's rapidly changing environment. Senior leaders remain confident
that through nimble management, the quality of the research at GMD FOKUS will remain high but some
concern was expressed about the quality of life of the researchers. An example of a long-term research
project at GMD FOKUS within the confines of a standard was the development of packet "scheduling
algorithms over the RF channel." This was viewed as a key point of differentiation between competing
UMTS compliant data service providers.

GMD FOKUS was starting to explore "Fourth Generation" concepts in collaboration with major equipment
manufacturers. At the current time, this new generation was viewed as extending the range and mobility
support for broadband wireless access. Investigations were also underway on the concept of "Secure Cellular
IP Networks." Long-term research plans at GMD FOKUS include MAC, FEC/ARQ, software radio, HFR,
radio independent access, and mobility routing. Applied research is focused on hardware/software prototype
development, and GMD FOKUS does get involved in pre-product development through the creation of
networking software and software tools.


FOKUS ORGANIZATIONAL STRUCTURE

FOKUS was recently structured around nine centers of competence:
1.   CATS, the Competence Center for Advanced Network Technologies and Systems, is focused on the
     development and implementation of new communication protocols, systems and services.
2.   GLONE, the Competence Center for Global Networking, is focused on Internetworking services over
     various underlying technologies, enabling global communication, services procurement, and service
     quality guarantees.
3.   MAGIC, the Competence Center for Multimedia Applications for a Globally Interacting Community, is
     focused on various aspects of interworking communication systems including issues of convergence.
4.   PLATIN, the Competence Center for Distributed Object Technology, Platforms, and Services, aims to
     support new business opportunities that emerge from value-added, customized service provisions.
     ECCO, the Electronic Commerce Competence Center, offers products, services, and consultation on the
5.
     design, specification, and development of electronic commerce platforms and applications based on
     state-of-the-art technology.
6.   IMA, the Intelligent Mobile Agents Competence Center, offers services and consulting on the definition,
     specification, and development of agent platforms and applications based on state-of-the-art Intelligent
     Mobile Agent technology.

                                   Appendix C. Site Reports--Europe                               89

7.   MOBRA, The Competence Center for Mobile and Broadband Wireless Communications, pursues
     advanced R&D for protocols, interfaces, and applications of mobility in wideband/broadband
     multimedia networks.
8.   TIP, the Competence Center for Testing, Interoperability and Performance, offers services and
     consulting on analyzing, testing, measuring, and monitoring LAN and WAN components and
     applications.
9.   OKS, the Competence Center for Open Communication Systems, investigates technologies, platforms,
     and services to provide universal service access.

                                         Appendix C. Site Reports--Europe
90

Site:                    German National Research Center for Information Technologies (GMD)
                         IPSIInstitute for Integrated Publication and Information Systems
                         Dolivostrasse 15
                         D-64293 Darmstadt
                         Germany

Date Visited:            28 April 1999

WTEC Attendees:          A. Ephremides (report author), R. Pickholtz, L. Katehi, T. Itoh, D. Friday

Hosts:                   Professor Dr. Wolfgang Schoenfeld
                         Mr. Matthias Hollick, GMD-IPSI
                         Ms. Nicole Berier, GMD-IPSI
                         Professor Dr. Ralf Steinmetz, Professor, GMD-IPSI and Technical University of
                              Darmstadt
                         Dr. Lars Wolf, Technical University of Darmstadt
                         Ms. Ana Pajares, Technical University of Darmstadt

BACKGROUND

GMD is the principal research organization of Germany that is primarily publicly funded and that focuses on
information technology. Although detailed budget figures were not presented, a broad picture of GMD's
activities emerged from the discussion. The organization is composed of eight institutes each of which
focuses on separate (although interrelated) sectors of research activity. Four of these institutes are located in
the Bonn area (along with GMD's headquarters); two are located in Berlin; and two in Darmstadt. IPSI
focuses on information distribution. As such it encompasses activities in the following:
    information management
    digital libraries
    information "publication" (in the broad sense of the term)
    future working environments
    mobile interactive media
    cooperative environments
The main activity of the institute that formed the basis of the discussion for the purposes of this study was
that of mobile interactive media. As it emerged from the discussion, the main thrust of IPSI's efforts in this
area are focused on the upper networking layers (i.e., on the effects of mobility and of dynamic
environments on network protocols) and not on the wireless medium per se.

There is close interaction between personnel at IPSI and the research staff (faculty and students) of the
Technical University of Darmstadt. In fact, at the WTEC meeting, representatives of both organizations
participated.


DISCUSSION

After the WTEC panel made a brief introduction and described the objectives of the study, Professor
Dr. Schoenfeld proceeded with an extensive review of IPSI's programs on mobility issues. Later Professor
Dr. Steinmetz joined the meeting and complemented, with a brief commentary, the presentation of
Dr. Schoenfeld. After lunch, Dr. Wolf described some additional projects that are jointly pursued by IPSI
and the Technical University of Darmstadt. The meeting concluded with a broad discussion among all the
participants.

                                      Appendix C. Site Reports--Europe                                       91

The main focus of IPSI's programs in mobility studies is on seamless roaming for interactive multimedia in
dynamic environments in which the logical connectivity among the hosts and the routers is changing. As
such, it concentrates on the higher layers of the communication process.

As described by Dr. Schoenfeld, the objective of mobility tracking is to maintain consistent information
about every node's connectivity throughout the network. The networks of interest include WLANs, cellular
networks, fixed wireless systems, and even systems with satellite links. When an end-node in a routing tree
changes position, well-developed and well-understood methods of registration and reporting (from cellular
networks) can be used. However, when intermediate nodes change position and connectivity, then the
method of "tunneling" can be used. This method has formed the basis of mobile IP and represents a short-
term solution since the resulting new route is in general non-optimal. The long-term solution would have to
be based on rerouting. This is not easily accomplished in IP networks. Ongoing and future research on this
issue is addressing this problem.

In a sense, the search for improved solutions in this context suggests that routing in ad-hoc networks is an
important area that may have useful fallout in mobile computing. In fact, the DFN-Verein, which operates
the network that interconnects universities and research institutes in Germany, maintains an interest in
mobile computing and, through a new program, called MIRIAM, will permit IPSI to test the use or the
modification of mobile IP as part of the research in adaptive routing.

A related problem that IPSI is investigating involves the continuous registration of a mobile host at a
(possibly remote) home agent. The research concentrates on the theoretical modeling of this issue and on the
resource management problem that arises when links that support different quality of service must be
chosen. An E.U. project called COSMOS, in which IPSI is participating, addresses this issue. The role of
IPSI in this project, which assumes the use of satellite links as well, centers on middle-ware development.

Although IPSI recognizes the importance of the effects of the wireless link on the higher-layers (e.g., QoS
vis-a-vis mobility), its primary concern is the development of upper-layer protocols that are compatible with,
or are optimized for, dynamic topologies. By the same token, these upper-layer issues are crucially
important and, yet, are usually ignored by the physical-layer community.

To handle environment changes, a service location protocol is needed and a classification of services is
necessary in order to determine which services should be provided at which location. In this regard, it was
clarified that location refers to the notion of topological connectivity and not of actual position coordinates
(which is an objective of E-911 in the United States for future wireless services).

To assist in these projects, a Mobile Network Emulator is being developed that will actually include a link
propagation model.

In response to a question from the panel, it was clarified that multicasting applications are not currently part
of the focus in the IPSI projects.

The meeting, as mentioned earlier, included a description by Dr. Wolf, of the projects that are jointly studied
by the Technical University of Darmstadt and IPSI. These include a variety of topics that revolve around
multimedia networking from the point of view of content and information distribution. Some of these topics
are quality of service, heterogeneity, Internet telephony, security, gateways and protocols, content
processing, distance education, middle-ware, video servers, and content distribution. As the nature of these
topics makes it clear that the emphasis is on general networking and not on wireless networking.
Nonetheless, the relation to mobility (from the point of view of long-term mobility, i.e., the prediction of
needs at different locations) renders this research relevant to wireless networking. Also, the issue of pricing
of services, which in its own right has long-term implications for Internet networking as well as for wireless
communication, is on the research agenda of IPSI and the Technical University of Darmstadt.

                                     Appendix C. Site Reports--Europe
92

In the ensuing broadened discussion, in which the panel's hosts were explicitly asked to address the long-
term research issues and bottlenecks in wireless and mobile networking, it was mentioned that there is a
2005 Master Plan for IPSI. This Master Plan encompasses the areas of media streams (including
entertainment services), ubiquitous computing, education, applications (such as telemedicine), and
technology (e.g., security). Furthermore, it was pointed out that the ultimate bottleneck in network
communications would be the "usability" of the products and services, i.e., the needs and capabilities of the
consumer and user.


SUMMARY

The visit at IPSI highlighted issues in wireless networking that are often ignored by the wireless community,
namely the need to address the design of upper-layer protocols and their effects on link operation. However,
the WTEC panel visit verified that an integrated approach to networking that bridges gaps among layers is
needed but not yet in place.

                                      Appendix C. Site Reports--Europe                                      93

Site:                 IBM Zurich Laboratory
                      Communication Systems Department
                      Soodmattenstrasse 8
                      H-8134 Adliswil
                      Switzerland

Date Visited:         29 April 1999

WTEC Attendees:       T. Itoh (report author), D. Friday, L. Katehi, W. Stark

Hosts:                Dr. Pierre R. Chevillat, Mgr. Wireless Communication System
                      Mr. Martin Hug

BACKGROUND

The panel visited IBM's Zurich Research Laboratory in Switzerland and, more specifically, its
Communication Systems Department, located in Adliswil in a suburb of Zurich. This building is several
kilometers from the main laboratory. It is planned for this building to be vacated shortly, as this department
will be relocated to the main site. This is one of eight research laboratories of IBM. The others are the T. J.
Watson Research Center (headquarters), the Almaden Research Center, and the Austin Research Laboratory
in the United States. There are also research labs in Haifa, Israel; Tokyo, Japan; Beijing, China; and New
Delhi, India. The first three laboratories noted here employ 1,000, 800, and 220 people, respectively, while
the other five laboratories each employ 200 workers. IBM Zurich has three departments: Science and
Technology (famous for the number of Nobel prizes awarded), Communication Systems, and Applied
Computer Science (formally IT Solutions). The two latter departments comprise the major part of the
Zurich operation.


SYNOPSIS

Mr. Martin Hug and Dr. Pierre Chevillat greeted the WTEC panel. After the welcome and presentation of
the March 15 Workshop summary by the visiting panelists (T. Itoh, L. Katehi, W. Stark, and D. Friday),
IBM researchers made four presentations and one presentation/demonstration. The first two presentations
and the presentation/demonstration came from the Communication Systems Department and are more
engineering oriented. They are (1) "Mobile ATM" by Doug Dykeman, Manager of IP and ATM
Networking, and (2) "Short-Range Radio Communication, HomeRF vs. Bluetooth" by Dietrich Maiwald,
"Wireless Communication Systems," and (3) "Infrared Technology" (Short Lecture and Demostration) by
Walter Hirt, Wireless Communication systems. The remaining two were from Applied Computer Science
Department. They are (4) "`DEAPspace' Short-Range Wireless Communication" by Dirk Husemann, IT
Solutions, and (5) "Wireless Application Protocol (WAP)" by Carl Binding.

Fairly extensive discussions on the role of university research and on technical subjects have taken place
during the technical sessions. The presentations are mostly software oriented. Little description was given
on hardware as it is outside of the charter and operation of these departments and are in some cases worked
out at other facilities of IBM. The wireless subjects discussed were heavily oriented to data and computers.


MOBILE ATM

This project is for development of a mobile network integrated with a fixed infrastructure and is for aircraft,
ships, and large ground vehicles. Uninterrupted operation is the goal while mobility is hidden from the
users. Key protocols are ATM and IP for voice and data in the range of 0 ~100 kbps. This is a mobile ad-
hoc (reconfigurable) network.

                                     Appendix C. Site Reports--Europe
94

A new protocol called PNNI was introduced. PNNI routing has been accomplished while PNNI signaling is
still under investigation. ATM Forum Standardization is carried out, and the prototype implementation is in
progress with U.S. Navy through IBM's U.S. operation. The Federated Battle Lab of the U.S. DoD (Army,
Navy, and Air Force) and NATO are responsible for implementing the prototype, and a demonstration is
planned for September 1999.

Mobile IP, integration of IP on mobile ATM, and a new protocol for the future were discussed. The
problems to be addressed are Routing (ATM, IP) and Re-routing (ATM). In the future, voice needs to be
prioritized. Two problems that emerged from the discussions are the fading effect and frequency mobility
(jamming in a military environment).

Short Range Radio (HomeRF vs. Bluetooth)

Because of the evolution of consumer electronics devices, connectivity is now a problem. Items in this
category include digital broadband (ISDN, LMDS, etc.), cellular phones, and PCCS in a changing life style.
Interconnectivity should be built in, not created using many phone lines. The key to acceptance by the
customer is that these devices be made "easy, affordable and standard."

That is, the connection is interactive wireless without new wires. For Laptop and PDA, mobility is
important. For the short-range format, Cordless (DECT) and Radio LAN, 2Mbps, 2.4 GHz including
Hyperlan 1 (5.2 GHz, 10 Mbps) and Hyperlan 2 (5.2 GHz, 25 Mbps), are examples although simple infrared
LAN has a problem in diffusion and shadowing by wall so that this can be used for line of sight only.

The following initiatives, HomeRF and Bluetooth, must be considered:
    HomeRF is in the unlicensed band. Ten companies are founding members, but the numbers extend to
     87. HomeRF is based on DECT frequency hopping, IEEE 802.11 at 2.4 GHz ISM band, 1.2 Mbps
     frequency hopping, 100 mW, range of up to 50 m.
    Bluetooth is a project started by five companies. Membership has expanded to 612. Specifications are
     not firm, but a product was to appear in 1999. This system is based on a master/slave operation at 2.4
     GHz, 1 Mbps (1600 frequency hops). A single chip implementation is expected to cost less than $20.
     Ad hoc network capability will include up to three voice and seven data links. This architecture
     involves the replacement of cable, not a network. Applications include cable replacement, data access
     point, and personal ad-hoc networks.
HomeRF is a networking project, but Bluetooth is for people on the move. The RF section was worked out
at Yorktown. Future versions may use 5 GHz.


INFRARED TECHNOLOGY

IBM is working on advanced infrared wireless (AIr). Although similar physically to a TV remote control,
AIr requires wide-angle (360) coverage and long distance (10 m) data communication of 250 kbps to 4
Mbps with an LED of 900 nm wavelength. An experimental demonstration was provided during the WTEC
visit.


DEAPSPACE SHORT RANGE WIRELESS

This is a software project and the acronym came from Distributed Embedded Application Platform. The
objective is to connect nomadic and pervasive devices through transient ad-hoc and proximity-based network
for short-range (less than 10 m) applications. There is no master-slave arrangement but rather the devices
are allowed to talk to each other. The device characteristics are embedded into the microcontroller. There is
no central node. Challenges for this software development are a description of services, flexibility and
extensibility, simple process, and scalability. Currently, IBM has been working on simulation for transient

                                      Appendix C. Site Reports--Europe                                        95

ad-hoc networks and primitive test beds. Some of the competition is SUN's Jini, Microsoft's Universal Plug
and Play, and Xerox's PARC's UbiHome.

Support of Pervasive Application and Devices (Wireless Application Protocol or WAP)

This is an effort to develop an emerging industry standard for Internet style context to mobile users.
Currently, 90 members are helping to develop such a standard. An example is EasySabre (airline reservation
system with Web-like operation) where software translates html to WAP.


CONCLUSIONS

In the opinion of several WTEC panel members, this location understood the panel's objectives most fully.
IBM members, particularly the host, Dr. Chevillat, indicated their desires that the academy play an increased
role in future oriented, often non-targeted research because most companies are decreasing research
operations.


REFERENCES

White Paper "IBM Mobile ATM Networking Technology Overview." Version 2, August 1998.
Gfeller, F., and W. Hirt. 1998. "A robust wireless infrared system with channel reciprocity." IEEE Communications
     Magazine 36 (12).

                                       Appendix C. Site Reports--Europe
96

Site:                  Institute of Mobile and Satellite Communication Techniques (IMST)
                       (German name) Institut fur Mobil- Und Satellitenfunktechnik GmbH
                       Carl-Friedrich-Gauss Strasse2
                       D-47475 kamp-Lintfort
                       Germany

Date Visited:          26 April 1999

WTEC Attendees:        Dennis Friday (report author), T. Itoh, L. Katehi, R. Pickholtz

Hosts:                 Prof. Dr. Ingo Wolff, President, IMST and Rector, Duisburg University
                       Dr.-Ing. Mattthias Rittweger, Head of Department, RF Circuits and Systems
                       Dipl.-Ing. Johannes Borkes, Head of Department, Integrated Circuits and Systems
                       Dr. Ing. Dirk Heberling, Head of Department, Antennas
                       Will Chr. Will Hildering, Head of Department, Systems

BACKGROUND

IMST provides central engineering, test, and development resources for the wireless, telecommunications,
and information technology industries. Customers include almost all of the major European wireless and
telecommunication companies as well as companies throughout the Far East and Pacific, and Israel. The
intellectual resources at IMST include expertise in both the systems and the hardware aspects of
communications and information networks with a special focus on mobile wireless technology, both
terrestrial and satellite-based. Its wide-ranging technical programs include component and systems
engineering design, theoretical and experimental analyses, and special test and measurement services.

IMST President, Prof. Dr. Wolff, graciously served as the WTEC panel's host. The people it primarily
interacted with were the IMST equivalent of the board of directors, which included Dr. Wolff and all four
Department Heads. Dr. Wolff presented an overview of IMST, its history, its funding profile, its
organizational structure, its technical programs, its staff profile, its customers, and its goals. His presentation
was followed by more program-specific presentations by two of the four Department Heads. They talked
about wireless systems architectures, RF hardware design and performance, and antennas for wireless
applications.

The formal presentations were efficient summaries of the relevant IMST programs, and were enriched with
off-the-viewgraph insights, peripheral discussions, and open and informative replies to the many questions
from the WTEC team. The two-way interaction was intense and they adapted their agenda accordingly, but
there was much more to discuss than the panel had time for, constrained by the need to travel from and to
Frankfurt that day. Two of the department heads, with programs of interest to panel members did not give
formal presentations because of limited time, however they did participate in the discussions, and the panel
was given a condensed but comprehensive tour of the IMST laboratory facilities. Overall, the visit was very
productive.


IMST, THE CORPORATE MISSION, HISTORY, AND ORGANIZATION

IMST management referred to the organization as a workbench facility for the wireless telecommunication
and information technology industries. Special focus is on mobile and microwave communications
techniques for industrial applications, and much of the work is related to technology development and
evaluation for next-generation personal cellular/mobile communications hardware and systems. Their
economic niche is the gap between relevant cutting-edge research and industrial product development.
IMST helps companies bridge this gap by partnering with industry and performing the generic research and
engineering development work necessary to accelerate product development. This effort in turn reduces the

                                      Appendix C. Site Reports--Europe                                       97

risk to industry in new commercial ventures. In addition to its primary role as a gateway between research
and commercialization, IMST provides a broad range of expert technical services to industry, performs
measurements to characterize antennas and other components, develops and carries out specialized training
programs for industry, designs and fabricates special prototype hardware and software products for industry,
and even carries out market research studies for new systems.

The institute is a private, non-profit corporation (designated GmbH in German). The laws governing a non-
profit corporation in Germany are different from those in the United States. Most significant is the fact that
if a German company declares itself non-profit, at least 50% of its income must come from the government,
or it will not be recognized as a non-profit organization and be taxed as a for-profit company. However,
IMST, due to its special role as both a national resource and a key facility that will help the Duisberg region
attract high technology industries to compensate for their declining coal and steel industries, receives special
dispensation from this requirement. The IMST mission is to serve industry and to derive most of its funding
from the private sector. As a result of rapid growth in only a few years, and the excellent reputation
acquired, approximately 80% of funding comes from the private sector, and 20% from publicly-funded R&D
projects. Without special treatment as a non-profit company, IMST's programs would suffer financially.
Otherwise, IMST pays taxes like any other company. The success of IMST can be measured by steady
growth ever since it was formed, to over DM10 million of business in 1999.

Dr. Wolff told us that he and the four other managers present at the meeting, and the Vice President, assume
all the technical and financial responsibilities for the operation of IMST. They pointed out that, unlike in the
United States, the person who carries out all the legal work for the corporation is also an engineer by
training. Professor Dr. Ingo Wolff's commitment of time was especially significant since the panel learned
that, in addition to his position as President of IMST, he had recently been appointed Rector of Duisburg
University (equivalent to chancellor of a university in the United States) and was embarking on a major
restructuring within the university.

The IMST laboratories are located on a rural 10,000 m2 site a few kilometers across the Rhine from
Duisburg. The buildings contain 4,500 m2 of space, of which 1,500 m2 is laboratory space. The laboratory
space includes a 300 m2 clean room and several electromagnetic anechoic chamber facilities for antenna
characterizations, electromagnetic compatibility measurements, and related wireless technology experiments.
The building cost was DM12 million, and the total investment was DM17.5 million. Construction began in
1992, and the institute began operation in January 1993. IMST presently has 87 employees from 15
countries, including 68 engineers and scientists. IMST also maintains a close working relationship with the
University of Duisburg, and a total of 40 students work at IMST from there and from other universities.
Staff size has been approximately constant since early 1996.

The organizational structure is straightforward, consisting of an administrative branch and four departments.
Dr. Peter Waldow, Vice President of IMST, is responsible for operation of the company. He has
responsibility for central services, marketing, legal issues, technology transfer and intellectual property,
quality assurance, finances, and general administration. The four departments are Systems, Integrated
Circuits and Systems, RF Circuits and Systems, and Antennas & Electromagnetic Compatibility
(EMC). Overviews were only given by the Systems and the Antennas and EMC Department Heads. The
others were present throughout the meeting and participated in discussions.

The Systems Department, under the direction of Will Hildering, is responsible for communications
networks and systems, satellite systems, wave propagation, mobile systems, signal processing, and digital
electronics. The Antennas and EMC Department, under Dr. D. Heberling, is responsible for antenna
performance and characterization, EMC analysis and evaluation, and the interactions of human systems with
electromagnetic fields and wireless equipment. The RF Circuits and Systems Department, under Dr. M.
Rittweger, is responsible for electromagnetic modeling and simulation of devices and circuits, the design and
development of radio frequency (RF) circuits, modules, and printed wiring boards, and hybrid
microelectronics. The Integrated Circuits and Systems Department, under Dr. J. J. Borkes, is responsible for

                                       Appendix C. Site Reports--Europe
98

applications specific integrated circuits (ASICs), integrated communications circuits, RF circuits, and related
measurement techniques. Only two of the departments provided overviews, and the division of
responsibilities was not clear where there appeared to be an overlap.

IMST leverages its resources by partnering with industry, standards, and professional organizations. These
include ETSI, the UMTS Forum, the UMTS Development Partnership, ITG, FGF, IMEC, IMAPS, the
University of Duisburg, and other groups. They also are ISO 9000 accredited and maintain an ISO 9001
Quality System. They market worldwide by partnering with international technical marketing agencies.
Customers include many of the key telecommunications companies in Europe and Asia.


IMST, THE TECHNICAL PROGRAMS

IMST is active in a broad range of technical programs focused on both the physical and
architectural/algorithmic aspects of wireless systems communications.          Emphasis is on mobile
communications and 3rd Generation (3G) wireless technology. The role IMST plays in enhancing the
development and competitiveness of European and Asian wireless technology is significant. IMST serves as
a central laboratory resource for independent technology development, for reliable measurements, for
impartial performance evaluations, and for industry training and leadership. The main technical programs
will be summarized in the following paragraphs.

Antennas and Antenna Characterizations

Antenna design and prototyping is one of the services provided by IMST. The activity in this area ranges
from pure research for maintaining cutting-edge competence, to, for-contract, application designs, the latter
comprising mainly mobile radio antennas and microwave satellite communications antennas. Although
antenna design was not a strong component of the briefings, the WTEC study team did visit some of the
related laboratories and see some prototypes. The antenna design challenges for handheld units were for
innovative designs fully integrated with the geometry and space-location constraints of the handset. The
designs also incorporated information gleaned from antenna-human interaction studies. There was also
some work on integrated antenna-RF front ends. In addition to their design expertise, IMST researchers are
very strong in providing antenna characterization support for industry. Their antenna measurement facilities
are of high quality and used for characterizing a broad range of antennas for both terrestrial and satellite
communications. One is an indoor facility and the other is an outdoor range. The WTEC panel only visited
the indoor range due to time limitations, but received a description of the outdoor range and viewed it from a
distance.

The indoor antenna measurement laboratory is a totally shielded 8 x 12 x 5.5 meter facility used in two
modes, as a near-field facility and as a far-field facility. It is lined with pyramidal absorber and has a useable
frequency range from 400 MHz as a near-field facility (800 MHz as a far-field facility) to 50 GHz. The
measurement apparatus is a 2.5 x 2.5 meter automated planar near-field scanner procured commercially. As
a near-field facility it is used primarily for determining pattern, polarization, and gain properties of high gain
antennas used in satellite or long terrestrial links; and as a far-field facility, it is used for pattern and
polarization characterizations of electrically small, high frequency, low gain antennas used in hand-portable
or vehicular-mobile telecommunications applications.

The outdoor facility is a standard far-field range with a 110 m separation and a 23 m source tower. The main
applications are for characterizing pattern and polarization of physically larger and heavier antennas ranging
from low frequency antennas down to 50 MHz, to high frequency, high gain antennas up to 18 GHz. There
is also a mobile tower and a satellite-to-ground capability when longer baselines are required.

                                      Appendix C. Site Reports--Europe                                       99

Studies of Human-Antenna Interactions

IMST also has an antenna program that focuses on the effects of the human user on the handset antenna
pattern, RF front-end and propagation, and also on the EM field patterns in the human body, particularly the
head. The latter is for evaluating and designing for compliance with European EM exposure regulations.
IMST also has a well developed experimental and theoretical program for developing complete and realistic
models of the electromagnetic fields inside the human body and around the human user of a mobile
telephone handset, as compared to the handset in isolation. The research includes developing accurate
electromagnetically equivalent models of the typical human body at frequencies of interest and performing
accurate measurements of field patterns.

IMST has unique experimental facilities dedicated to modeling the effects of the human body on air link
performance. This work has several aspects. One is directed toward a standard measurement configuration
for comparing the performance of different handheld phones. A standard human replica artifact was
developed by combining simple geometric forms into a circularly symmetric saline-filled standard human
researchers call Charlie. The performance of different handheld units, both prototype and commercial, are
studied and compared by placing them adjacent to Charlie's head and rotating Charlie in an anechoic
chamber containing a receiving antenna that can scan vertically. The frequency range for this work is 10
MHz to 6 GHz. IMST offers a service for determining realistic radiation characteristics and specific
absorption rates in the human body based on this model and is working with ETSI to standardize the
procedure.

Researchers also developed another facility for performing measurements to determine human-body effects
on antenna and system performance and for use in modeling. The apparatus consists of a basin with a
surface contour corresponding to the right half of the human torso, oriented vertically. The basin may then
be filled with fluids that mimic the approximate electromagnetic properties of the human body at various
frequencies. If a handset is placed under the basin near the ear, then this design enables the field patterns to
be measured inside the head, or elsewhere in the body for biological studies and for modeling effects on
antenna performance. A precision computer controlled 6-axis robotic arm is used for precisely positioning
electromagnetic field probes on a spatial grid of points inside the fluid medium. The probes can measure
both the electric and magnetic near-fields of the transmitting antenna over a frequency range of 10 MHz to 3
GHz in fluid and up to 6 GHz in air. This facility is called the Dosimetric Assessment System, or DASY.
This facility is used for compliance tests for exposure limits as well as for optimizing new antenna designs.
Software modeling services are provided that link with these measurements.

Environmental Reliability Validation

IMST also has a range of peripheral services for evaluating the reliability of the designs in normal use. It
provides a sort of one-stop shopping lab for its customers' essential needs. There are electrodynamic shaker
facilities and a time-variable-temperature chamber for testing components and systems under vibrational and
thermal stress. Parameters such as voltage, current, frequency, power, spectrum (to 40 GHz), and bit error
rate are monitored during the environmental stress test to assess performance. Poor reliability can negate
any superior electrical performance in a commercial wireless product. The facilities are set up specifically to
test communications systems with coax and wave-guide connections to the unit under test.

Software Development and Services for Wireless Design and Modeling

IMST also performs the research and the software development necessary to produce and market a collection
of software packages for wireless design and modeling. One of the software products and services is a full
wave 3D FDTD PC program for solving Maxwell's equations. Called Empire, it has special wireless-design
oriented features for modeling RF microcircuitry as well as antenna performance and human body effects.
There is also a software package for nonlinear modeling of FETs called TOPAS that has been incorporated
into HP's EEsof design and simulation software package. MEDEA is a system for the design of Silicon ICs
incorporating thermal and electromagnetic constraints, while improving reliability and reducing costs.

                                      Appendix C. Site Reports--Europe
100

Coplan is a new design and simulation tool for design of coplanar waveguide (CPW) MMICs. It is
integrated with HPs EEsof and the user can perform simulations and optimization for GaAs designs up to 67
GHz. Customers can purchase the packages, but IMST staff can also provide solutions for the customer, as
well as use the software for internal research.

Characterization of Active Wireless Components

IMST provides measurement services for a wide range of wireless and microwave technologies. IMST has
well-developed laboratory facilities for characterization of devices, circuits, and components. The different
measurement systems are used for internal research and development projects and are also used to provide
complete measurement services for external customers. Some of the systems and related software are
offered for sale. The total program provides a wide variety of measurement capabilities and services for
both linear and nonlinear characterizations.

The following is a summary of capabilities:
     fundamental linear characterizations
     scattering parameters: two- and three-port, 40 MHz to 110 GHz
     spectrum analysis
     thermal noise: 1 to 26.5 GHz
     noise figure: 100 MHz to 26.5 GHz
     phase noise
IMST has developed its own methodology and instrumentation for characterizing various nonlinear
properties of devices, circuits, and systems for one-port, two-port, and three-port configurations. Some of
these capabilities are not commonly available and may incorporate unique analysis methods. This is also an
active research program for new techniques. These methods are available for on-wafer (coplanar geometry),
microstrip, and coaxial lines. Unfortunately we did not see their microstrip measurement techniques.

The following are some of the specifications for harmonics and intermodulation products:
     load pull: 410 MHz to 110 Ghz, >80 dB dynamic range, > 10 W
     power sweep: up to 110 Ghz, > 10 W, VNA analysis
Electromagnetic Compatibility Design and Assessment

IMST has extensive expertise in both modeling and measurements for characterizing electromagnetic
compatibility of radio/wireless products. Modeling software and experimental facilities include an anechoic
chamber. These capabilities are used to perform research, as well as to provide customers with data and with
test services to determine whether product emissions satisfy U.S., international, and E.U. trade compliance
regulations. IMST is on the U.S. FCC list of approved facilities for certification of specific absorption rate
for handheld products headed for the U.S. market. EMC compliance of all electronics/wireless products and
official recognition of test facilities are significant issues in wireless for the global market.

Design and Prototyping

IMST provides services for design and prototyping of RF devices and RF front-ends. Excellent RF design
software is available, both in-house developed and commercially available software. Capabilities include
CAD, simulation, optimization, and EM field simulation for RFICs, MMICs, ASICs, hybrids, and
communication systems. It has complete clean room and GaAs fabrication facilities (300 sq. m - class 100
to 10,000) for developing prototype devices and systems. IMST is very active in this area. Some of the
projects include the following:

                                     Appendix C. Site Reports--Europe                                    101

   new, more efficient devices and microcircuit geometries (layered, etc.)
   RF front ends for handsets
   RF modules for communications transcievers
   complete radio systems including a software radio that was really an RF front end with a software
    reconfigurable digital/systems section
Overall this effort comprised a significant portion of the activity, and IMST demonstrated a successful
history of having designed and developed the RF sections, and other components, for many successful radio
products manufactured by well-known international electronics/wireless companies in both Asia and Europe.


SUMMARY/CONCLUSIONS

IMST is, by its mission, and the work it engages in, forward looking. The projects all reflect the cutting-
edge technology for commercial products. IMST's brief history combined with its growth and successes
speaks for its capabilities. In short, IMST appears to be well embedded in the enabling technologies
underlying the worldwide wireless industry, and its management and technical staff are competent and in a
good position to observe major trends and assess emerging technologies. Programs address important
problems in the wireless industry. For example, in addition to GSM refinements, IMST is active in UMTS,
DECT, and general 3G and 4G issues. The current focus, with the exception of satellite technology, is
almost totally terrestrial, portable, and mobile.

IMST sees the wireless industry evolving as essentially mobile technology embedded in adaptive
architectures and believes that the mobile economy will expand astronomically. IMST researchers stated
that Europe is not interested in LMDS for Europe, just as a possible product to sell abroad wherever it is
marketable. As a result, it is not receiving much attention and no energy is being expended in this area with
respect to standards activities or R&D as happened on GSM or is now happening on UMTS. No one
believes that a market exists in western Europe for LMDS systems or services in western Europe, because
there is already a hard-wired infrastructure that will meet all European needs. IMST researchers also aren't
convinced that the performance of broadband wireless systems at 30 MHz frequencies will be superior to
wired broadband systems or to advanced mobile systems.

The broad but focused range of programs covers virtually all hardware aspects of wireless. Many of the
designs exhibited were straightforward but well executed. Other designs reflected innovation and
experimentation. The centralized wireless-focused design, device prototyping, software services, test and
measurement services, and products provided are clearly an asset to customers, and enhance
competitiveness. While the WTEC panel saw no great departures from conventional technology, IMST is a
key facility and a lab to watch. Two examples of programs that best reflect cutting edge thinking and
planning are the nonlinear circuit and device modeling and characterization project and the elaborate
theoretical and experimental program to assess the interactions of the handset antenna and the human user
and model the effects on propagation, RF circuitry, and field levels in the body. The significance of these
projects is the contributions they will make to aspects of wireless design that are presently only partially
characterized. Devices in handheld units are always operating in or near saturation to optimize battery life
and the design process to optimize the nonlinear behavior is a black art. Propagation paths can degrade 3 to
5 dB when the typical GSM phone is placed near the head, and other wireless units have exhibited 8 to 10
dB degradation in the hands of users. These are important programs and important wireless issues.

                                      Appendix C. Site Reports--Europe
102

Site:                 Nokia
                      P.O. Box 45
                      00211 Helsinki
                      Finland

Date Visited:         27 April 1999

WTEC Attendees:       W. Stark (report author), N. Moayeri, R. Rao, J. Winters, A. Ephremides, L. Young,
                           M. Iskander

Hosts:                Heikki Huomo, Vice President, Research and Technology Product Creation
                      Yrjo Neuvo
                      Antti Yla-Jaaski

BACKGROUND

Nokia is a leading manufacturer of wireless communication equipment, including cellular phones and base
stations. Nokia has research facilities across the world including Helsinki and Richardson, Texas. Nokia
revenue has been increasing at a rate of roughly 30-35% per year for the last 15 years. Nokia has led the
industry in marketing phones. Nokia has hired outside companies for research including TI for research on
solid state devices. Nokia spends about 8% of sales on research and development. Not all of this was
internal research as Nokia sponsors research by other companies and universities. Nokia has 44,543
employees in 45 different countries with research centers in four countries.

The meeting at Nokia began with a fairly large group (around 30) of engineers, product developers. These
engineers were participating in a continuing education program whereby Nokia brings in experts from
universities together with Nokia engineers. Nokia has a formal mentoring type of program for engineers in
order to continue their professional development. This may be quite unique compared to many other
companies.

The meeting had several parts. First, Prof. Ephremides, chair of the WTEC panel, gave an overview of the
goals of the study and sponsorship. Second, two members of the Nokia research staff, Hekki Huomo and
Antti Yla-Jaaski made presentations, followed by discussion and questions from the panelists. After this, a
lunch meeting with Hekki Huomo and Antti Yla-Jaaski was held, where further discussion regarding
research took place.

At the first part of the meeting, research areas of interest to the panel relevant to wireless communications
were discussed. Dr. Neuvo of Nokia added display technology and EMC effects to the list of important
research areas.

Dr. Huomo discussed the generations of wireless systems from first generation AMPS/NMT to third
generation, from analog modulation to digital modulation. The second to third generation is from mainly
voice to a combination of data and voice along with packet oriented services.

He also discussed wireless computing where the data rate is from 2-155 Mbps, the carrier frequency is much
higher (2GHz and above), and the service is best effort. The architecture of the network is also not celluar/
hierarchical. The future drivers for wireless communication include multimedia communications. A new
way of presenting information is needed. The Internet was a success because of available content with
intuitive access. A means of differentiating between personal data and work-related data was also discussed
as a future goal. Data would be gathered, in this scenario, depending on whether the user is at home or in the
office.

                                      Appendix C. Site Reports--Europe                               103

It was suggested that service and protocols will have more influence in the future and that the driver of
technologies will be service and application protocols and not more capacity (as is the current driver).

The following list of technologies needed to achieve these applications was suggested:
   board assembly/packaging
   chip scale packaging
   RF passive integration with MCM-D
   flip chip technology
   filer integration with BAW
   CMOS RF
   enhanced digital and analog ASICs (Productivity in ASIC design must grow so that a Pentium can
        be designed in one man-year)
   product architectures
   mechanics
   user interface
   external interfaces
   antennas
   battery and energy management
   software defined radios (SWDR)
   technology to create multimode and multiband radios
   technology to create mobile multimedia platforms
   radios that are flexible and easily configurable
   Software or quick design cycles
   radios based on virtual components

SUMMARY

Nokia is a very product oriented company with a heavy emphasis on marketing cellular phones. It has
become an international company, leading the industry in cellular phones, and is focusing on systems
integration. Nokia has a unique system for mentoring employees with university faculty. The research
drivers for future wireless communications include high speed, high frequency transmission of multimedia
data, and personalizing data retrieval. The research topics needed to achieve this include board
assembly/packaging, chip scale packaging, RF passive integration with MCM-D, flip chip technology, filer
integration with BAW, CMOS RF, enhanced digital and analog ASICs, user interfaces, external interfaces,
antennas, and battery and energy management.

                                      Appendix C. Site Reports--Europe
104

Site:                 Philips Research Laboratories
                      Prof. Holstaan 4
                      5656 AA Eindhoven
                      The Netherlands
                      http://www.research.philips.com/generalinfo/laboratories/netherlands.html

Date Visited:         28 April 1999

WTEC Attendees:       J. Winters (report author), M. Iskander, N. Moayeri, R. Rao, W. Stark, L. Young

Hosts:                Dr. C.P.M.J. (Stan) Baggen, Research Fellow, Digital Signal Processing
                      Dr. H.A. (Rick) Harwig, Director, Electronic Systems
                      Dr. Peter Baltus, Research Scientist, Integrated Transceivers
                      Dr. Marcel J.M. Pelgrom, Department Head, Mixed Signal Circuits and Systems
                      Dr. Paul Kaufholz, Research Scientist, User-System Interaction Technology
                      Prof. Dr. J.W. (Hans) Hofstraat, Department Head, Polymers & Organic Chemistry
                      Dr. Jean-Paul M.G. Linnartz, Senior Scientist, Broadband Communications &Video
                            Systems
                      Dr. Carel-Jan L. van Driel, Department Head, Digital Signal Processing Group
                      Dr. C.R. de Graaf, Senior System Architect, Compact Personal Communicator

BACKGROUND

Royal Philips Electronics is one of the world's biggest electronics companies and Europe's largest, with
sales of $33.9 billion in 1998. Founded in 1891 in Eindhoven, the Netherlands, it is a global leader in color
television sets, lighting, electric razors, color picture tubes for televisions and monitors, and one-chip TV
products. Its 233,700 employees, in more than 60 countries, are active in the areas of lighting, consumer
electronics, domestic appliances, components, semiconductors, medical systems, business electronics, and IT
services. The WTEC panel visited Philips Research Laboratories in Eindhoven.

Philips Research was started in 1914, and currently has 3,000 employees worldwide, with 1,700 employees
in the headquarters in Eindhoven. The major research areas are materials (29%), electronics (15%), and
software, systems and devices with a budget of $600 million for research out of an R&D budget of
$2.2 billion. Over 60,000 patents have been issued to Philips Research, which is the backbone for corporate
technology strategy.

Rick Harwig, Director of Electronic Systems, gave an overview of the work at Philips Research
Laboratories, describing the various projects and achievements that have been made. He noted that there are
currently 150-200 people involved in wireless, and the number is expanding at a slow rate, due to the lack of
qualified candidates.


RESEARCH AND DEVELOPMENT ACTIVITIES

The panel heard six technical talks on research projects at Philips Research Laboratories. Peter Baltus,
Research Scientist, discussed RF front ends for wireless communications. He first noted the trend to higher
data rates and frequencies, with outdoors up to 5 GHz and indoors greater than 10 GHz for higher
bandwidths. He saw the main issues for RF electronics as lower cost, low weight and volume, and long
talk/standby time.

Noting that the RF front end consumes more than 50% of the total power in a handset and currently uses
more than 20 external components, he stated that the main challenges are the integration of the transmitter,
integration of the antenna interface, multiband/multimode operation, and A/D technology. This includes

                                         Appendix C. Site Reports--Europe                                   105

eliminating external impedance matching circuits and duplexer components, along with advanced antenna
diversity. Since Philips is primarily involved in handsets (e.g., in DECT), the main emphasis of the
discussion was on techniques for handsets. Baltus described the Philips scanning dual-antenna handset,
noting the need for better radio channel characterization. He then stated that one method for power
reduction was the elimination of the substrate to get around parasitics' problems and discussed Philips
Silicon-on-Anything technology and how this technology could be used to integrate high Q resonators.

Marcel Pelgrom, Department Head, Mixed Signal Circuits and Systems, discussed A/D conversion and
power management for future digital systems. He noted the tradeoff of resolution versus bandwidth in A/D
converters, which results in large power at high resolution and bandwidth. The challenge is to achieve
high-speed/resolution A/Ds so that multichannel transceivers can be integrated for lower cost. The trend in
higher resolution/bandwidth A/D converters was seen to be continuing for another 6 to 10 years, with
3 orders of magnitude improvement still left. This should result in practical A/D converters for WCDMA in
4-5 years. In power management, the trend in increasing energy per weight and size was seen through the
evolution of batteries from NiCd to Li-ion to Li-poly to future unknown materials.

Interestingly, one of the best research areas for power management was seen to be in better power
management software, including improved protocols. It was stated, however, as in the previous talk, that RF
power will dominate over software power, and additional digital signal processing (DSP) will not
compensate for poor A/Ds. Thus, he felt that long-term research should emphasize RF and packaging
research over DSP/software improvement, although software improvement can have some effect on RF
design.

Paul Kaufholz, Research Scientist, User-System Interaction Technology, discussed voice control in the
living room. He noted that with more wireless devices in the future, there would be a growing need for
better user interfaces to these devices, in particular, voice control. The key challenges were seen to be
acoustic speech recognition and echo cancellation.

Hans Hofstraat, Department Head, Polymers & Organic Chemistry, discussed polymers: new options for
electronics. With polymers, the main advantage is very low cost. Currently, polymers are used for LEDs
today, and he demonstrated such a device. In 2-3 years they should be used in electronics, and in 5-10 years
in batteries. This has the potential to reduce costs to the point that disposable wireless phones may be
feasible. However, substantial research is still needed, with particular emphasis on multidisciplinary
research, which is a challenge.

Jean-Paul Linnartz, Senior Scientist, Broadband Communications & Video Systems, discussed wireless
system issues. In particular, he felt that as higher data rates stretched the limits of bandwidth, wireless data
systems would evolve to a frequency reuse of 1 (frequency reuse in every cell). With this reuse in
combination with dynamic channel assignment, research was needed into channel assignment with data
packets, i.e., dynamic packet assignment. He also stated that there should not be one system to handle both
short messages and high data rate services such as HDTV, but a combination of systems. Furthermore, for
higher data rate systems the trend may be away from spread spectrum type of systems.

C.R. de Graaf, Senior System Architect, Compact Personal Communicator, discussed ultrawide bandwidth
systems and briefly described the possibility of placing the transceiver on a chip.

After the presentations by Philips, Ramesh Rao presented the results of our national workshop to a seminar
group of about 50 Philips employees. There were discussions with the group covering the above areas,
including discussions on ultrawide bandwidth systems.


REFERENCES

Philips Research Brochure, "Science emanates not just from the mind, but also from the heart."

                                        Appendix C. Site Reports--Europe
106

Mosaic of Philips Research, Number 5, 1998.
Baltus, Peter. "RF front ends for wireless communications." viewgraphs.
Kaufholz, Paul. "Voice control in the living room." viewgraphs.
Hofstraat, Hans. "Polymers: new options for electronics." viewgraphs.

                                                                                                            107


APPENDIX D. SITE REPORTS--JAPAN

Site:                  Advanced Telecommunications Research-International (ATR-I)
                       2-2 Hikaridai
                       Seika-cho, Soraku-gun
                       Kyoto 619-0288
                       Japan

Date Visited:          31 May 1999

WTEC Attendees:        A. Ephremides (report author), R. Pickholtz, R. Rao, J. Maurice, B. Mooney

Hosts:                 Dr. Bokuji Komiyama, President
                       Dr. Nagao Ogino
                       Mr. Keizo Inagaki
                       Mr.Yuichiro Ohno

BACKGROUND

ATR is an institute/laboratory established in 1986 as a joint organization. Each laboratory receives 70% of
its support from Japan's Key Technology Center (Key Tec) and 30% from private companies, whose
mission is to engage in high risk, basic research ventures in the broad field of communications.

Its mode of operation is fairly unique in that it is based on externally approved, seven-year projects that are
manned with personnel mostly borrowed from participating companies.

The WTEC panel visited only one of the current four seven-year projects (referred to as laboratories within
ATR). This laboratory, called the ATR Adaptive Communication Research Laboratories, was established in
1996 and is currently operating with a budget of 11.9 billion for the period 1996-2003.

The other three (established respectively in 1995, 1993, and 1992) are the ATR Media Integration and
Communications Research Labs, the ATR Interpreting Telecommunications Research Labs, and the ATR
Human Information Processing Research Labs.

When its seven-year cycle expires, a project may be continued if its goals are not yet fully accomplished or it
may be discontinued if it has fully achieved these goals. The goals consist of patenting and commercializing
the products of the research effort. The term used within the organization for the latter is managing the fruits
of research. Currently, there are four such successfully completed projects.

The overall annual budget for all four operating laboratories is currently 7.4 billion.


DISCUSSION

The WTEC panel visit commenced with a round-table welcome and introduction by Dr. B. Komiyama, the
President of the ATR Adaptive Communications Research Labs. As explained by Dr. Komiyama, the Labs
consist, in turn, of four departments.    There is one department on Architecture for Adaptive
Communications, one on Design and Control of Adaptive Systems, one on Advanced Wireless
Communications, and one on Advanced Communication Devices.

Dr. Komiyama had selected four projects to brief the panelists in detail. Two of these are in the department
of Architecture for Adaptive Communications and focus on upper-layer issues and the other two are in the

                                      Appendix D. Site Reports--Japan
108

department of Advanced Wireless Communications and focus on lower-layer issues. Specifically, the
former two include self-organizing wireless networks and adaptive QoS management, and the latter two
include microwave photonics and intelligent antenna arrays.

The briefings on these projects were conducted by the respective directors or principal investigators and took
place within the specific lab environment of each project. All were explained in detail and were
accompanied by demonstrations.

Self-Organizing Wireless Networks

This project focuses on the development of an ad-hoc, flat network with adaptive topology control. The
ultimate objective is to test topology control algorithms on a real testbed and to include routing and media-
access-control (MAC) provisions. In addition, the algorithms are envisioned to operate in distributed
fashion. For the moment, the emphasis is on centralized algorithms and limited to logical connectivity
control (clustering). The main idea is to adjust the clusters based on the changing traffic conditions.
Presently, the investigators are using genetic algorithms as the basis for such topology control. The intended
applications include stadium events or other similar gatherings of large numbers of users.

Adaptive QoS Management

The objectives of this project are to develop adaptive ways in which application-level QoS is controlled in
response to changing environments in multimedia applications. The current focus is on controlling the
compression and transmission parameters of video streams (bit-rate, frame-rate, etc.) through negotiation
among network agents that correspond to the different user streams. It is later expected that these
negotiations will include allocation of additional network resources (such as buffer memory, bandwidth,
etc.). The investigators do realize that end-to-end QoS performance depends on lower-layer (link) QoS
parameters and intend to include this coupling into their methods. At the time of the site visit, there was
focus on the use of motion-JPEG because of its scalability. Thus, other stream formats are converted to
motion-JPEG before the adaptive negotiations are performed.

Microwave Photonics

The goal of the project is an imaginative use of optical signal processing for adaptive antenna array
applications. Unfortunately, the speed and complexity of the needed FFT computations limit most
algorithms for beam forming. This project proposes to convert the microwave signals up to infrared optical
bands, perform the FFTs through a lens (essentially instantaneously), and then convert the signal back down
to its natural carrier frequency. The multitude of problems associated with this idea, laser frequency
stability, non-reciprocal structures at transmitter and receiver for the up and down conversions, and the
electro-optical integration, are currently being addressed. This project is an excellent instantiation of
integration across layers in wireless networking. In this case, the hardware, the beam forming, and the signal
processing are all coupled in a unified design approach.

Intelligent Antenna Arrays

This project is close to current mainstream research that is geared toward multi-user CDMA applications. It
focuses on beam forming and tracking for both narrow-band and wideband cases for the simultaneous
reception of several signals. Constant Modulus Algorithm (CMA) techniques, that are blind, as well as
recursive tracking techniques (based on Kalman filtering) are used; and experiments are conducted with 44-
tap transversal filters, 16 or 32 antenna elements, and simultaneous operation of 4 beams. The difficulty of
multi-beam A-to-D conversion (in terms of needed processing bandwidth) is recognized and will be
addressed.

                                      Appendix D. Site Reports--Japan                                    109

CONCLUSIONS

True to the stated mission, these labs are focusing on long-term research. The technologies they are focusing
on include the challenging one of ad-hoc networking and are illustrating a visionary integrated approach
across layers. They also reflect perfectly the perceived need for spatial diversity, hardware/software
integration, and coupling of QoS to lower layer networking issues.

                                      Appendix D. Site Reports--Japan
110

Site:                 Fujitsu Laboratories
                      4-1-1 Kamikodanaka, Nakahara-ku
                      Kawasaki 211-8588
                      Japan

Date Visited:         3 June 1999

WTEC Attendees:       N. Moayeri (report author), A. Ephremides, B. Mooney, H. Morishita, R. Rao, W.
                          Stark

Hosts:                Jifeng Li, Researcher, Wireless Communication Systems Laboratory, Network
                            Systems Laboratories
                      Tamio Saito, Senior Researcher, Wireless Communication Systems Laboratory,
                            Network Systems Laboratories
                      Yukio Takeda, Director, Wireless Communication Systems Laboratory, Network
                            Systems Laboratories

INTRODUCTION

Dr. Takeda started the meeting at 9:35 a.m. and went over the agenda for the meeting. Dr. Ephremides then
outlined the WTEC panel goals for the visit.

Dr. Takeda gave the first Fujitsu talk on the organization of Fujitsu Laboratories, Ltd., which was established
in 1968, has about 1,500 employees, and has capital of 5 billion. He discussed Fujitsu, Ltd., which was
founded in 1935, has over 180,000 employees, and had consolidated revenues of $44 billion in the fiscal
year, which ended in March 1999.


RESEARCH AND DEVELOPMENT

Dr. Takeda discussed the Wireless Communication Systems Laboratory, which consists of 25 employees and
which he is in charge of. The laboratory is concentrating on 3G and 4G wireless systems and Intelligent
Transportation Systems (ITS). In 3G and 4G the researchers are investigating interference cancellation using
multiuser detection and adaptive array antennas for W-CDMA base stations. He showed a picture of two
hardware racks researchers have developed to study the two approaches mentioned above. These were
developed in collaboration with FTRC. In the ITS area researchers are developing a millimeter wave radar.

Dr. Saito presented a talk on interference cancellation and mobile multimedia communications. He talked
about the drastic increase in the number of wireless communication users in Japan. Two data services are
currently offered in Japan, a 28.8 kbps service for PDC users and a 64 kbps service for PHS users. The
interference cancellation scheme is a two-stage system, followed by a RAKE receiver. This system results in
1.6 Db performance improvement at a BER of 10(-3). This results in an almost doubling of system capacity.
However, in practice in a multi-cell system, the capacity improvement is only 1.3. In the practical system
the interference cancellation scheme is applied to high rate data users, because they transmit at higher
powers. Multiuser detection is also employed. The system can cancel a maximum of 32 interferers.

In the second part of his talk, Dr. Saito described the Multimedia Mobile Access Communications Promotion
Council (MMAC-PC) and its collaborations with IEEE 802.11B and ETSI BRAN. Fujitsu is considering
two systems, one with a bit rate of 6-10 Mbps (with a maximum of 25 Mbps) in the 25/40/60 GHz band and
another with a bit rate of 156 Mbps in the 60 GHz band. These systems are for stationary or slow moving
users. He gave some details on the physical link aspects of these two systems and mentioned that the work
on the MAC layer is underway.

                                     Appendix D. Site Reports--Japan                                  111

Next Dr. Li described turbo coding for W-CDMA, which Fujitsu is proposing to standardization bodies such
as ARIB and ETSI and recently within 3GPP. Turbo coding is used for higher data rate modes of W-CDMA
and possibly CDMA2000. He went over a Fujitsu puncturing method for turbo codes and compared it with
another one proposed by the Korean company LOGIC. The Fujitsu approach was slightly better at higher
signal-to-noise ratios. In addition, it was simpler to implement.

He then described a multidimensional turbo-coding scheme, which used three decoders in each iteration. He
showed the performance of this coding scheme when used in conjunction with W-CDMA over the FPLMTS
Vehicular B channel model. It shows improvements over the conventional turbo coding method.

He then briefly talked about interleaver design for turbo coding, specifically a modified symmetric
S-interleaver. In the discussion following Li's presentation, the issue of the tradeoff between degree of
spreading and the coding rate for the turbo code came up. This is an open question for low bit rate users.


CONCLUSIONS

The panel heard about Fujitsu's activities on 3G wireless systems and beyond. The hosts went over an
interference cancellation method they have studied and experimented with. The researchers have built a
hardware test-bed for use in a laboratory environment (as opposed to field tests) for their experiments, a
trend that was observed in many other Japanese companies. WTEC panelists also heard about Fujitsu's
activities on multimedia mobile communications within the framework of MMAC-PC. Technical
specifications are now available for MMAC.

Fujitsu is collaborating with other industry partners to build a prototype for MMAC-type systems. It has a
project on turbo coding with an emphasis on reduced complexity decoding algorithms. In particular, their
researchers have looked at interleaver design and multidimensional turbo coding. Fujitsu has some research
activities with a 1-2 year timeline, such as the work on 3G wireless systems, and some with a 5-7 year
horizon, such as the work on 4G wireless systems.

                                      Appendix D. Site Reports--Japan
112

Site:                 KDD Research and Development Laboratories
                      2-1-15 Ohara Kamifukuoka-Shi Saitama
                      356-8502
                      Japan

Date Visited:         31 May 1999

WTEC Attendees:       W. Stark (report author), N. Moayeri

Hosts:                Dr. Takuro Muratani, President and CEO
                      Dr Masayoshi Ohashi
                      Takeshi Mizuike
                      Hiroyasu Ishikawa
                      Kenichi Minamisono
                      Yoshio Takeuchi
                      Satoshi Miyaji

BACKGROUND

KDD Research and Development Laboratories (KDD R&D) is the main research part of KDD. KDD R&D
employs about 150 researchers on a variety of topics ranging from mobile wireless communications to
underwater fiber optical communications. The laboratory is organized into 17 different laboratories and
research units.    The laboratories conduct research on multimedia, Internet, radio and mobile
communications, lightwave communications, network design and management, and other areas.
Fundamental research is particularly active concerning devices for optical communication systems.


DISCUSSION AND RESEARCH PROJECTS

The meeting began with welcomes and introductions. Dr. Takuro Muratani explained the focus of the
laboratories. The WTEC panel members gave a presentation focusing on the purpose of the visit. Then,
KDD R&D personnel gave several talks. Hiroyasu Ishikawa presented research on carrier frequency offset-
spread spectrum method for wireless LAN system using 2.4 GHz ISM band. Yoshio Takeuchi presented
information on field trials for IMT-2000. The panelists saw a demonstration of a very low bit rate video
codec transmitting information of a wireless link (albeit stationary) given by Satoshi Miyaji. Finally,
Takeshi Mizuike gave a presentation on computer software development for radio communication systems.

Carrier Frequency Offset-Spread-Spectrum Wireless LAN

This project uses the 2.4 GHz ISM band to transmit 10 Mbps for a wireless LAN system. The method of
operation is essentially a multicarrier operation with 5 different carriers each spread by a factor of 11 and
uses a bandwidth of 26 MHz. The current system is point-to-point, using directional antennas. The next
generation system will be point-to-multipoint and have data rates up to 18 Mbps. In 2000, an LSI was
expected to replace the baseband processing portion of the CFO-SS wireless system.

Field Trials for IMT-2000

The purpose of this project was to verify the performance of wideband CDMA, collect design and
operational parameters, and verify new services and applications. The implementation included an
interference canceller that has linear complexity in the number of interfering signals and had performance
close to that of a decorrelating detector. In addition soft handoff performance and control was verified. The
system was a DS-CDMA/FDD system with 4.096 Mcps (million chips per second) using 5 MHz of
bandwidth with convolutional and Reed-Solomon codes. The interference canceller was a multi-stage

                                     Appendix D. Site Reports--Japan                                   113

canceller. The wideband CDMA data rate was 8 kbps for voice, 64.128 kbps for circuit switched data, and
up to 384 kbps for packet transmission.

Low Bit Rate Video Codec

A demonstration of a low-bit-rate video codec was given to the visiting panel. The codec uses a technique
called advanced precoding to provide optimum bit allocation to regions of the video containing significant
information when a pre-analysis of each picture frame is completed. The low rate coding makes video
transmission possible at rates down to 15 kbps, albeit with some compromise in video reproduction,
especially for moving images.

Design Tool for Cellular and Microcellular Networks

KDD R&D has developed software tools for cellular and microcellular planning. The tool CSPLAN does
cell site planning and coverage evaluation for microcellular mobile systems using low antenna height. The
features include integration of 2-D building shapes into a geometric computation technique for path loss
calculation. The tool BSPLAN does propagation prediction and coverage evaluation for mobile base station
planning. The features include integrating practical pathloss models with geographic and building databases
utilizing building height information average over a 250 m square mesh.


SUMMARY

KDD R&D Laboratories presented products developed during short term R&D projects. These products are
derived from basic research activities and include wireless LAN systems for point-to-point operation, low
rate video compression for sending video over a wireless link, and base station location planning software
tools. Long-term basic research has been conducted, for example, in the area of devices for optical
communications but was not part of the discussion. KDD R&D indicated that basic research requirements
include propagation modeling and large scale mathematical optimization for base station location planning.

                                      Appendix D. Site Reports--Japan
114

Site:                 Matsushita Electric Industrial Co., Ltd
                      Central Research Laboratories
                      3-4 Hikaridai, Seika, Soraku, Kyoto, 619-0237
                      Japan

Date Visited:         31 May 1999

WTEC Attendees:       D. Friday (report author), M. Iskander, L. Katehi, H. Morishita

Hosts:                Dr. Osamu Yamazaki, Director, Central Research Laboratories
                      Dr. Tomoki Uwano, General Manager, Central Research Laboratories

                      The following three participants in the Kyoto meeting are from the Matsushita, Osaka
                      site, Device Engineering Development Center, 1006 Kadoma, Kadoma City, Osaka,
                      571-8501, Japan:

                      Dr. Eng. Toshio Ishizaki, Senior Staff Engineer, Communication Devices Group
                      Koichi Ogawa, Manager, Communication Devices Group
                      Hiroaki Kosugi, Manager, Communications Devices Group

BACKGROUND

Matsushita Electric Industrial Co., Ltd. is a large, 80-year-old corporation with a diverse range of products
and a complex domestic and international network of subsidiaries. The corporate headquarters is located in
Osaka, and the company and its brand names are generally known outside of Japan as Panasonic, National,
Technics, and Quasar. Sales in 1998 totaled $70 billion. Matsushita's research programs are equally diverse
and the wireless communications programs of the Central Research Laboratory near Kyoto are just one
component of a more expansive program. The companys forward looking corporate research and
development programs are located in four divisions, the Corporate Research Division, the Corporate
Development Division, the Corporate Semiconductor Development Division, and the Corporate Production
Engineering Division. The WTEC panel visited the Matsushita Central Research Laboratories (CRL), one of
three laboratories under the Corporate Research Division. Another Corporate Research and Development
branch, focused on wireless technology, is the Matsushita Research Institute Tokyo (MRIT), Inc. MRIT,
which is under Matsushita Engineering Limited (MEI), was also visited by WTEC and its work is described
in a separate site report. The Tokyo Communications Systems Laboratory, referred to during the CRL visit,
is assumed to be either MRIT or a part of MRIT. Lighting research, multimedia, optical data storage,
document technology, and automotive electronics were some of the other activities. The WTEC panel was
fortunate to be hosted by Dr. Yamazaki, the Director, and Dr. Uwano, the General Manager of the Central
Research Laboratories.

Matsushita added value to the panel's visit and accommodated its limited time schedule by having three
senior managers from the Communications Devices Group of the Device Engineering Development Center
in Osaka, a branch of the Corporate Development Division, travel to the CRL site, to participate in the
WTEC meeting. Their participation was appreciated and provided much relevant information.


MATSUSHITA CRL, THE WIRELESS VISION

Professor Katehi presented a very brief overview of the WTEC Panel, its objectives, the process by which
the final report would be developed and reviewed, and the fact that the final report would be made available
to Matsushita and all of the hosts. The Matsushita presentations began with a brief overview by Dr.
Yamazaki in which he described the corporate structure and its research component. The Matsushita

                                      Appendix D. Site Reports--Japan                                     115

Corporation employs a total of about 20,000 engineers. Corporate sales worldwide total about $70 billion.
The total Corporate Research and Development investment each year is approximately $700 million, and
3000 people are on the staff. Of these, approximately 2000 are engineers of whom about 200 are in the
Corporate Research Division. Some of the research is carried out under joint industry-government
cooperation. No information was provided on the nature of this cooperation. The Central Research
Laboratory consisted of 50 people. Matsushita also has more than 10 information technology research
laboratories overseas.

The hosts presented a vision of a highly competitive company, operating in a rapidly evolving wireless
technology world, where the horizon is close and the main challenges are to identify and achieve the key
technological advances necessary to manufacture and market competitive wireless products a few years in
the future. This view was essentially consistent with all of the European and Japanese sites visited and with
the presentations of the U.S.-based companies.

Dr. Uwano then provided an overview of current technical challenges and programs and the lab's vision of
the main current issues in wireless technology. The main challenges are in two areas of mobile wireless
technology: compact base stations and smaller card-sized handsets.

The compact base station challenges were classified into three areas: microcell stations, multicarrier power
amplifiers, and optical fiber network links. The most important underlying base-station hardware issues that
Matsushita CRL was addressing were performance improvements and cost reductions for antennas, low-
distortion power amplifiers, notch filters, RF-optical modules, GaAs FETs, and SiC devices.

The main compact handset challenges were identified as smaller and lower-profile RF components, higher
performance built-in antennas, component and handset designs for integrated electromagnetic compatibility,
and the one-chip RF-inclusive IC. The specific hardware challenges engineers were addressing were lower
power consumption, higher performance electronics, innovative new concepts for small antennas, HBT, high
dielectric-constant ceramics, and improved SiGe device technology. Handsets have been steadily reducing
in volume from 600 ml in 1986 to near 50 ml today. The component sizes have been reducing likewise,
primarily the power amplifiers, antenna-duplexers, synthesizers, VCOs, TCXOs, etc. A chart presented,
using volume as a measure of progress, showed the current size-limits of these components to be
approximately 0.1 ml. Matsushita is focusing on innovation and continuous incremental advances in design
and fabrication to push these technologies, reduce size and cost, and maintain its competitive position.


MATSUSHITA CRL, THE TECHNICAL PROGRAMS

Dr. Eng. Toshio Ishizaki, from the Communications Devices Group, described in detail a concept for filter
design that Matsushita is using, the laminated planar filter. The filter consists of a 9-layer planar complex
geometry of alternating conductive and dielectric planes, having a sharper roll-off on the low end (or high
end) than conventional filters, a reasonable rejection ratio (up to >40 dB), flexibility in design for various
applications, and, most important, a significant reduction in volume. The Q is approximately 200.
Researchers developed the necessary asymmetric elliptic function theory and techniques for laminating the
ceramics and have implemented several filter designs. The stated size reduction was to one twentieth of a
conventional filter, or approximately 4.5 x 3.2 x 2.0 mm. Matsushita researchers also told the WTEC panel
that their next objective was to use this laminated planar technology to develop the world's smallest
dielectric duplexer. Their target volume here is 0.08 cc. The immediate application that Matsushita has for
this technology is for laminated, band rejection, dual-band, and balanced input-output filters, from 800 MHz
to 5 GHz, for super compact IMT2000 and GSM dual-mode phones. A typical portable phone will have a
total of 6 IF and bandpass filters as well as the duplexer.

Researchers also continue to work on performance improvements and cost reductions for GaAs MMICs and
modules for both base and mobile applications. With regard to the mobile wireless stated previously,
Matsushita is developing super-linear GaAs, MOS power amplifiers for W-CDMA base stations. The

                                      Appendix D. Site Reports--Japan
116

underlying principle is a feed-forward linearization control design that effects cancellation of the nonlinear
distortion. Matsushita's experimental data showed a 15 to 20 dB improvement in the height of a multi-
carrier, 64-code W-CDMA spectral plateau.

Koichi Ogawa, also from the Communications Devices Group, described in detail some antenna and RF-
circuit programs. He described a stacked switched-beam mm-wave sector antenna where each layer
consisted of two back-to-back antennas each with a 60 degree beamwidth. Three such layers, appropriately
aligned and semiconductor switched, provide 360 coverage. The 7 dBi inherent gain is reduced to
approximately 4 dB, because of a 3 dB PIN diode loss and a 0.5 dB loss for the cylinder. The design
prevents shadowing between the separate beams and, likely, frequency reuse.

He also described a GaAs 25 GHz 2 stage DRO oscillator based on a dielectric constant of 32. The present
goal is to achieve a Q of 50 - 60,000 for cellular frequencies, but not millimeter wave bands for now. He
said new materials are needed to achieve these goals.

He briefly described a 50 GHz antenna intended for mobile TV and video transmissions. It has a 40 cm
case, uses MMIC technology, and has a gain of 42 dBi. The signal can reach 20 km with clear skies. Earlier
related work at Matsushita was on the Strategic Defense Initiative (the so-called U.S. Star Wars program).
This work was stopped and it is now restarting, but is directed toward Multimedia Mobile Access (MMAC).

Hiroaki Kosugi, from the Communications Devices Group, and Dr. Ishizaki described some of their RF-
circuit technology programs. They are exploring a very broad range of possible technologies in pursuit of
the ultra-small, low-cost, high-performance one-chip RF-IC including GaAs MMICs, SiGe, Bi-CMOS,
CMOS, GaN, SiC, and flip-chip. They are targeting 0.05 cc volumes for power amps, VCOs etc. They see
linearity for Class A/B amplifiers as an important issue. They summarized RF design as a filter problem,
and the 1 to 5 GHz band as the largest market area. Problems with GaAs remain: the yield is not great, there
are environmental issues, and costs. Researchers see GaN on Si Carbon for high power as a promising
technology. There are problems with non-uniformity, however, that have to be addressed. SiGe is looking
promising for low-power ICs.

Although base stations are an important part of the Matsushita market niche and the company's research and
development programs, there are no programs in High Temperature Superconductor (HTS) filter technology
for base station applications. Matsushita formerly had an HTS program for base station filters but a
corporate decision canceled it. Reasons for this decision included reliability concerns, the emergence of
competing technologies that are closing in on HTS performance gains, inadequate models, inter-modulation
problems, and cost. However, Matsushita personnel are watching the evolution of HTS technology and are
prepared to restart the HTS-base station program if, at some time in the future, performance and reliability
issues warrant doing so.

When asked about their plans for LMDS, Matsushita personnel said that they saw little future in Japan for
LMDS technology since the country is so well wired. However this was somewhat in contrast to a
communication network architecture slide shown (with fixed high-bandwidth wireless channels), and some
of the mm-wave hardware projects that indicated that broadband wireless access (both fixed and mobile) is
clearly going to be a component of future high-bandwidth communication links. It may be that they
interpreted the LMDS question in a very narrow sense and with broad application or were implying there
would be less use for it in Japan than in Matsushita's overseas markets.


SUMMARY/CONCLUSIONS

While research directed toward future technologies remains critically important, choosing a winner among
possible future technologies is becoming more difficult. The rate of evolution of technologies, markets, and
ideas is such that it may no longer be reasonable to think in terms of 10 or 15 year plans, except for very
general goals. In fact five years may be pushing limits for planning of current programs in directed research,

                                      Appendix D. Site Reports--Japan                                      117

development, and manufacturing. Two to three years in the future appears more realistic. This was the
message from Matsushita, as well as other sites visited.

With respect to wireless technology, the technical hurdles to make everything smaller, less costly, more
versatile, and better (in performance) are the prime challenges for Matsushita. SiGe and GaN and advanced
Si technologies seem promising. Matsushita is not betting on HTS for base stations. Improved materials
present a very critical issue for all aspects of wireless technology. New advanced materials are needed, such
as high dielectric constant ceramics with low losses and no temperature dependence, for example. Low
dielectric constant films for passivation layers, low cost-effective shielding materials for EMC, and
frequency agile materials for tuning are other materials requirements. Packaging materials are also critical to
cost and performance. Matsushita personnel concluded with the assertion that they would rather have low
distortion devices than software radio. High speed A-to-D is costly, and computation and software
reconfigurability cost in power consumption. They said that the future is in semiconductor technology,
whichever system technology or technologies survive. Improvements in filters, packaging, and interconnect
technology are also important challenges. Piezo-ceramic materials and electro-optical devices are two
technologies they are exploring for potential new directions and technology leaps. Diversity in systems and
components is also a competitiveness criterion that they target. They see high-quality adaptive antennas and
RF circuits, both for mobile and fixed applications as a future requirement. On-demand bandwidth changes
and multiple antennas in handsets, laptops, and base stations for spatial and frequency diversity are also a
part of this vision. They also talked about potential handset diversity requirements and adaptive network
architectures that could at the extreme include terrestrial as well as LEO, MEO, and HEO satellite links.
They don't see a strong need for Bluetooth technology for LANs in houses. They briefly mentioned the need
for better propagation models for new environments (such as indoor and urban) and for higher frequencies in
these environments.

In summary, the Matsushita CRL focus is on RF and antenna hardware aspects of wireless technology, and
primary research is directed toward incremental and innovative advances in RF circuits, materials, devices,
antennas, fabrication, and semiconductor technologies.

                                     Appendix D. Site Reports--Japan
118

Site:                 Matsushita Research Institute Tokyo (MRIT)
                      3-10-1 Higashimita
                      Tama-ku
                      Kawasaki 214-8501
                      Japan

Date Visited:         4 June 1999

WTEC Attendees:       L. Katehi (report author), T. Itoh, W. Stark, M. Iskander, R. Pickholtz, D. Friday,
                           J. Maurice, N. Moayeri, B. Mooney

Hosts:                Dr. S. Yamashita, President of MRIT
                      Dr. M. Makimotom, MRIT
                      Dr. M. Sagawa, MRIT
                      Mr. M. Hasegawa, MRIT
                      Mr. K. Takahashi, MRIT
                      Mr. S. Ueno, MRIT
                      Mr. Y. Watanabe, MRIT
                      Mr. H. Ogura, MRIT
                      Mr. R. Hori, Director of Matsushita Communications Industrial Co., Ltd. (MCI)
                      Mr. K. Kurosawa, MCI
                      Mr. N. Nakajima, Matsushita Electric Industrial Co., Ltd. (MEI)

INTRODUCTION

MRIT is the Matsushita group's R&D Center located in Tokyo. The center employs about 230 research
engineers. Matsushita Communication Industrial Co. Ltd. has six production plants in Japan, two in Europe,
one in the United States, one in Mexico, and eight in Asia. The business areas the company emphasizes are
in Communications, Automotive Electronics, Professional Audio/Video and Data Processing, and
Measurements with annual sales of about 800-900 billion, with about 600 billion coming from Japanese
markets and about 250 billion from international markets.

The major drive in the Japanese wireless market is the reduction of cellular phone size to less than 100 gr,
less than 68 cc, and with more than 330 hours of lifetime. To respond to the needs of the market and
develop infrastructure that allows for engineering innovations, Matsushita has a number of closely
collaborating centers including Matsushita Battery Industrial, Matsushita Electronics Components, the Multi-
media Development Center, the Matsushita Semiconductor Engineering Center, and the Matsushita Research
Institute Tokyo (MRIT).

To capture the market, the company is quickly moving to W-CDMA planning to have products available by
2001. The wireless phones the company presently has available are PDC and GSM. However, the product
line includes CDMA-1 to help the company expand to the American market and TDMA for future wireless
devices. For the third generation mobile communications world the company is preparing products for
home/office/public applications, which will be based on W-CDMA and mobile IP. Furthermore, the
company is developing products for home and office security.


MRIT AND RESEARCH ACTIVITIES

MRIT is trying to develop an advanced mobile communication technology that will facilitate movement
towards a multimedia society. Basic technologies for mobile communications include microwave devices
and circuits, antennas and propagation, digital wireless systems, and wireless data networks. The research
efforts under each area are given below.

                                       Appendix D. Site Reports--Japan                                      119

Microwave Devices and Circuits

The major effort of MRIT is concentrating on the development of miniaturized, high performance
components for a low cost RF system on a chip technology. Furthermore, emphasis is placed on the
development of novel millimeter-wave integrated circuits, RF filters with high Q and small size, in addition
to wireless terminals, radar sensors, and other RF components.

Antenna & Propagation

In this area the research is concentrating on the development of an integrated antenna design technology
such as millimeter-wave built-in antenna, antenna array for ETC, adaptive array antennas and digital beam
forming. Finally, in wave propagation, there is a serious effort in multi-path analysis and wireless system
design.

Digital Wireless Systems

For digital systems, research is underway for the development of an advanced Codec Technology. Also
work is performed in high-speed data transmission, high performance receiver technology (diversity,
adaptive equalizer, OFDM) and base-band digital signal processing.

Wireless Data Networks

Internetworking protocols for wireless communications is a large research subject with specific emphasis on
Routing, mobile IP, terminal mobility etc. The company is looking at the development of advanced cruise-
assist highway systems, multimedia wireless LANs and dedicated short-range communication systems. The
attributes of the mobile multimedia access communication systems under study are shown in Table D.1.

                                                 Table D.1
                      Attributes of Mobile Multimedia Access Communication Systems
                   Attributes                 High Speed Wireless Access       Ultra-High Speed Wireless
                                                                                         LAN
           Frequency Band               25/40/60 GHz                           60 GHz
           Transmission Rate            Av. 10 Mbps (Max 25 Mbps)              156 Mbps
           Mobility                     Low                                    Stationary
           Service Area                 Indoor/Outdoor                         Indoor


W-CDMA (IMT 2000)

Matsushita's W-CDMA systems feature global roaming, multimedia transmission of 8 kbps to 384 kbps
(2 Mbps) and high frequency utilization. The W-CDMA products extend from voice to visual terminal to PC
card terminal to ground stations.


SAMPLE RESEARCH EFFORTS

MRIT is funding a variety of research efforts, some of which are described below.

Millimeter Wave System Integration on a Chip

The millimeter wave is expected to be a frequency resource for the next generation's mobile communication
systems and is aimed at achieving a high frequency PC-card-type radio terminal. To realize all the wireless
functions, including the antenna and the filter on a chip, a three-dimensional hybrid IC structure is one of the

                                      Appendix D. Site Reports--Japan
120

most effective solutions. Matsushita has recently developed a 3D millimeter-wave IC that uses silicon
micromachining. For the development of this IC several technologies have been utilized including dual
mode resonant filter, multi-layer thin-films on silicon and flip-chip bonding for the GaAs devices. This
circuit has been utilized in a 25 GHz receiver down converter and has an area of 11 mm2 including the built-
in micromachined filter.

High-Power Amplifier Linearizer

In vehicular telecommunication systems, the nonlinear distortion introduced by the power amplifier in the
transmitter has to be compensated for through high efficiency. Matsushita has developed a linearizer by
means of the "hybrid adaptive pre-distortion method," which is characterized by much less complexity and
less power consumption than the "feed forward method." This method was found experimentally to provide
a satisfactory ability to compensate for linear distortion and to improve efficiency in the amplifier.

Adaptive Array Antennas

With a fixed zone adopted for base stations, it is possible to increase the number of mobile stations in one
area and realize efficient frequency utilization by changing the antenna patterns of the base station
adequately. Matsushita has developed a system that recognizes the direction of the arriving beam and turns
the antenna in that direction by adaptively changing the phase and amplitude of the individual radiators. The
configuration of this system allows for high speed tracking of the various mobile stations. A high resolution
algorithm is applied to the eight antenna elements and enables a very good estimation of the direction of
arrival.


VISION ON WIRELESS COMMUNICATIONS TECHNOLOGIES FOR THE 21ST CENTURY

Matsushita's vision is summarized in the following and is discussed separately on issues related to (1)
infrastructure (see Table D.2), (2) bottlenecks, and (3) important R&D activities.

                                                 Table D.2
                                               Infrastructure
      Projections           PCS-Mobile Internet                 Fixed Services            Other Applications
Next 5 years          W-CDMA (384 kbps-mobile)            LAN: 20-30 Mbps              Electronic Toll Collection
                                                                                       System (ETC)
Next 10 years         10-20 Mbps Mobile                   LAN: Very High Speed         Road-side Vehicle, inter-
                                                          100 Mbps                     vehicle communication
Next 15 years         156 Mbps                            LAN: Ultra-High Speed 1      Advanced Cruise Assist
                                                          Gbps                         Highway System

Bottlenecks

The issues Matsushita identified include the following:
     bandwidth expansion can be accomplished using higher frequencies for microcell and picocells
      frequency resource reassignment
     fading and interference issues can be resolved through error collection and PA linearization.
      Furthermore, multicarrier (OFDM) issues as well as diversity and pencil beam antennas are research
      areas in which the company is investing
     portability can be accomplished via use of compact/low-power devices/components and systems, low-
      cost packaging and high-density integration, in addition to high-energy density batteries
     interoperability also can be achieved via appropriate protocols to connect different systems, software
      radio, and global standard communication systems

                                        Appendix D. Site Reports--Japan                                     121

R&D ACTIVITIES

Table D.3 shows the areas in which the company is investing heavily.

                                                  Table D.3
                                         Areas of Heavy Investment
       Devices               Antennas            Signal        Modem and    Compression-        Networks
                                               Processing        Codec       Multimedia
High-speed, high-        High Directivity,   Linearizers       Adaptive    Adaptive Multi-    Seamless
frequency devices        Planar Antennas                       Modem       rate codec         architectures
Micromachined devices    Integrated          Parallel Signal   Interfer.   Error              Routing for
                         Antenna-Circuits    Processing        Canceller   concealment        mobile
                                                               Software    Compression
Interconnect/Packaging   Adaptive            Spatial and
                                                               Radio       using visual and
                         Antennas            Temporal
                                                                           audio
                                             Signal Process.
System on a Chip         Dynamic Cell
                         Control

                                     Appendix D. Site Reports--Japan
122

Site:                Mitsubishi Electric Corporation
                     Information Technology R&D Center
                     Ofuna 5-1-1, Kamakura
                     Kanagawa, 247-8501
                     Japan

Date Visited:        2 June 1999

WTEC Attendees:      R. Rao (report author), W. Stark, R. Pickholtz, N. Moayeri, H. Morishita

Hosts:               Dr. Takashi Katagi, General manager of the R&D Center
                     Dr. Kenji Itoh, Mobile Communication Business Division
                     Dr. Makoto Miyake, Wireless Communications Department
                     Dr. Osami Ishida, Microwave Electronics Department
                     Dr. Isamu Chiba, Antennas Department
                     Dr. Tokumichi Murakami, Multimedia Information Coding and
                           Transmission Technology Department

INTRODUCTION

Hosts for the WTEC panel were primarily from the Wireless Communications and related departments.
Research and development activities include the design of cellular and cordless phones, third generation W-
CDMA systems for IMT-2000, a European ACTS program called SAMBA, satellite communication
systems, and multimedia systems. The company representatives were careful to point out that they were
expressing their personal views (on matters of interest to the WTEC study team) and did not necessarily
reflect the official views of the Mitsubishi Corporation.

Takashi Katagi presented a brief overview. Mitsubishi employs about 45,000 employees, of whom 3,500 are
involved in R&D. The R&D personnel were either affiliated with five divisional centers (1,500 in all) or
served at a corporate center (2,000). In the area of computers, communications and audio-visual products,
Mitsubishi has 800 R&D staffers of whom 600 were engineers. The research horizon extended out to ten
years.


RESEARCH AND DEVELOPMENT

Subsequently, presentations were made on RF devices, direct conversion techniques, and the SAMBA
project. This was followed by two facility tours of a Quasi Geosynchronous Satellite system under
development, as well as a Digital Television Model Station studio.

Dr. Kenji Itoh described in some technical detail the work on the Even Harmonic Type Direct Conversion
Receiver (EH-DCR) ICs for mobile handsets. This work represented efforts to produce "single chip" light
weight terminals. The experimental aspect of this work involved testing the performance of EH-DCR based
receivers for the 1.9 GHz PHS receiver (TDMA access) and X-band satellite (CDMA) system. The ability to
overcome the lower sensitivity of the direct conversion technique was based on second-order harmonics
suppression characteristics of even harmonic mixers. Lowering the weight and size of terminals is
apparently a very high priority at Mitsubishi.

Dr. Makato Miyake then described Mitsubishi's role in the European ACTS project (AC 204) entitled
"System for Advanced Mobile Broadband Applications (SAMBA)." The objective of the SAMBA project is
to demonstrate the Mobile Broadband System (MBS) and to design and implement radio transmission of
ATM cells to mobiles. The overall work was conducted by the SAMBA consortium, led by Portugal
Telecom, which included members of BBC, Daimler Benz, DASA, Bosch, Mitsubishi, and others.

                                      Appendix D. Site Reports--Japan                                     123

The carrier frequency used was 40 GHz. A TDMA/FDD multiple access scheme was employed, using a
OQPSK modulation that supported a transmission bit rate of 64 Mbps and an ATM cell bit rate of 34 Mbps.
Terminal mobility of up to 50 km/h was supported using omni antennas at the terminals and directional
antennas at the base station. For baseband signal processing, five ASICs covering equalization, detection,
modem control, TRX control, and FEC Codec have been developed. The SAMBA platform was
successfully demonstrated at the Lisbon EXPO in September 1998. The intended applications include TV
news gathering and telemedecine.

The facility tours included a demonstration of the phased array antenna and its deployment, used in the
inclined (as opposed to equatorial) GEO satellite communication system. In this system, the satellite
illuminates multiple beams from an elevation angle that is high enough even in non-equatorial zones, to
minimize degradation due to shadowing. The use of a large antenna array (the panelists were shown a 256
element array) is designed to enable high data rate communication with small portable terminals. One of the
innovations described to the WTEC panel was the use of electrical to optical conversion to lower the weight
of the antenna array (as low as 300 g per square meter) while extracting the signal received by the individual
antenna elements for array processing.

The Mitsubishi Model Digital TV studio was visited briefly. The WTEC panelists were shown some
prototypes of very large screen displays that rendered razor sharp images of impressive quality as well as
MPEG-2 encoders, multiplexers, and other equipment for digital broadcasting. The panel also learned of
Mitsubishi's vision of home networks, based on the IEEE 1394 bus, designed primarily for the distribution
of audio-visual signals.


SUMMARY

The Information Technology R&D Center of the Mitsubishi Electric Corp. shared research on mobile
communications ranging from systems to devices. The research horizon extended out to ten years and an
overarching concern was reducing the size and weight of handsets. This concern impelled researchers to
explore (1) cross layer opportunities for effecting efficient communications and (2) battery technologies to
extend life or reduce weight. They had active collaborations with European initiatives such as ACT and
shared the same vision of fourth generation systems as most other Japanese companies visited.

                                       Appendix D. Site Reports--Japan
124

Site :                 Murata Manufacturing Company
                       Technical Management Department
                       Nagaokakyo-shi, Kyoto 617-8555
                       Japan

Date Visited:          1 June 1999

WTEC Attendees:        L. Young (report co-author), L. Katehi (report co-author), D. Friday, J. Maurice

Hosts:                 Hiroshi Kuronaka

BACKGROUND

Murata Manufacturing Company, Ltd., was founded by Akira Murata in 1944 and incorporated in 1950. Dr.
Murata continues as honorary chairman of the company. Chairman of the Board is Osamu Murata, and
President and CEO is Yasutaka Murata. Financial and other statistics (as of some time in the spring of 1998)
were as follows: The parent company has some 50 subsidiary companies, half of them in Japan, the rest
overseas, employing a total of nearly 24,000 employees, of whom the Japanese parent company alone
employs about 4,500. Annual sales for the parent company alone (in dollar terms) were said to be
$2.4 billion, but on a "consolidated basis" (which the panel understand to include all subsidiary operations)
were $3.0 billion. R&D expenses are 6.6 percent of sales (both for the parent company alone and also on a
"consolidated" basis). The company is capitalized at approximately $0.5 billion.

Murata's headquarters staff (Kyoto) is organized as follows:

Operating Divisions
1.    Research and Development Division
2.    Product Divisions (see also Note below)
      -   Material Division
      -   Component Division #1
      -   Component Division #2
      -   Device Products Division
      -   Circuit Products Division
      -   Sales & Marketing Division
Note: The Product Divisions include product strategy, development and design, and sales promotion in
Japan, but each division has production facilities both in Japan and overseas, which enables the company to
maintain close working relations with the customer.

Sales by world regions are as follows (rounded to the nearest integer): Japan 38%, Asia 25%, Europe 19%,
and the United States 18%.

The panel visited the Yasu plant at company headquarters in Kyoto, where the number of employees is
1,850. The other major plant in Japan, not visited by the panel, is in Yokohama. Research is carried out
both in Kyoto and in Yokohama. Kyoto seems to do more basic and design work, while Yokohama tests
final products. For example, a large anechoic chamber at Yokohama is used for electromagnetic interference
(EMI) suppression testing of systems containing Murata EMI suppression filters.

                                       Appendix D. Site Reports--Japan                                     125

CURRENT PRODUCTS

The company holds a very strong position in the manufacture of ceramic materials and devices. Its success
is based largely on the ability to manufacture ceramics and to design useful devices incorporating these
materials better and cheaper than probably anyone else.

Murata's technology policy leads to integration of processes: Material, Processing, Design and Production.
This approach is followed in all component and element design. About 10 billion capacitors are produced
per month. Murata has extensive tools for design and analysis has developed its own manufacturing
equipment. Material characterization is performed via resonator measurements using the HP equipment.
This method will become an IC standard next year.

Sales by product area are as follows (rounded to the nearest integer): capacitors 40 percent, piezoelectrics 21
percent, circuits 12 percent, coils 5 percent, resistors 4 percent, other 18 percent.

Murata has a world dominant position in several products. Global market share in 1996 was as follows:
ceramic filters (CERAFIL) and resonators (CERALOCK) 80 percent, chip monolithic ceramic capacitors
50 percent, microwave dielectric filters (GIGAFIL) 40 percent, PTC thermistors (POSISTOR), suppression
filter (EMFIL) 35 percent.

Murata's main products include the following:
   EMI suppression filters for DC as well as AC
   RF filters: ceramic dielectric as well as surface wave acoustic
   circuit modules: active filters, high voltage power supplies/switching power supplies, hybrid ICs, tuners
   microwave components: dielectric filters, oscillators, VCOs
   CRT peripherals
   sensors: pyroelectric IR sensors, thermal cutoffs, temperature sensors, ultrasonic sensors, piezoelectric
    sensors, secondary electron multipliers, magnetic sensors, piezoelectric vibrating gyroscopes, vibration
    sensors
   capacitors:   ceramic capacitors, high-voltage capacitors, monolithic ceramic capacitors, trimmer
    capacitors
   resistors: thermistors, trimmer potentiometers
   other electronic components: ceramic resonators, piezoelectric buzzers and speakers, coaxial connectors,
    ferrites, conductive paste, surface acoustic wave (SAW) resonators, dielectric resonators
These products find industrial and consumer electronic applications in the following areas:

Industrial Electronic Equipment
   wired communications: facsimiles, telephones/cordless telephones, electronic exchanges, modems
   telecommunications: mobile and portable telephones, pocket beepers/pagers, personal wireless phones
   computer equipment: computers, printers, CRTs, I/O devices
   offices: word processors, photocopiers, PCs and peripherals
   measuring instruments: test instruments, industrial instruments, sensing instruments
   automation: numerically controlled machines, industrial robots, power saving equipment
   other industrial: ultrasonic appliances, electronic appliances

                                      Appendix D. Site Reports--Japan
126

Consumer Electronic Equipment
     consumer video equipment: VCRs, camcorders, TVs, digital cameras, videos/disc players/DVDs
     consumer audio equipment: CD players, radio cassette recorders, headphone stereos, hi-fi stereos, car
      audio equipment, DBS, CATVs
     home appliances: heating and air conditioning appliances, kitchen equipment, personal care appliances,
      home sanitary equipment, home security equipment, health monitors/equipment
     automotive and other electronic components: HF circuit components, power supply circuits, integrated
      circuits, motor control, circuits, clocks, optical equipment, car electronics, electronic toys
In addition there is a multiplicity of chip products, among them monolithic ceramic capacitors, ceramic
trimmer capacitors, coils, thermistors, ceramic filters, SAW filters, discriminators, multilayer LC filters,
multilayer delay lines, coaxial connectors, microwave filters, dielectric antennas, multilayer antennas.

Murata is a device and components company with a strong materials as well as design background and
capability, which has now expanded into chip design. Its willingness to cooperate closely with the customer
in integrating its devices into his equipment, and where possible in measuring customer equipment
incorporating Murata's products, has contributed materially to its success.


ONGOING PRODUCT DEVELOPMENT

The presentations covered ceramic multi-layer devices, surface acoustic wave filters, and dielectric filters.
Most of this work is based on the company's ceramic material formulations combining high dielectric
constant with high Q (low dielectric loss), and good thermal stability in both dielectric constant and
temperature coefficient of expansion. Murata ceramics are known as the best in the world. Dielectric
constants range from 20 to 13,000. A value of 3000 is most popular. Ceramic dielectric constants are
notoriously temperature sensitive, but one material changed only 10% from 45 C to +85 C.

Filters are developed using piezoelectric materials PZT and multi-layer technology for very low frequency
applications from 400 kHz region up to 10 MHz. In addition ferrite materials are used to develop
transformers and noise suppression filters. Pyroelectricity is material property explored by the company for
sensor development. Furthermore semiconductor materials are used for the development of thermistors.

The kind of device used for filtering depends, among others, on frequency and power levels. Thus SAW
filters are good at lower power levels and better at the lower frequencies. Piezoelectric filters have been
used up to 450 kHz with an unloaded Q of 400 and only about  mm on the side. Ferrites are glossy
ceramics attenuating because of their magnetic properties and are used for EMI suppression.

As with presentations at all sites, not all the work in Kyoto could be covered. For example, dielectric
resonators and GaAs semiconductors, were mentioned only briefly.

The company has a good capability to design microwave combline and stepped-impedance filters and
duplexers to specified performance. These dielectric filters are constructed in a neat miniaturized
monoblock construction out of a block of high-dielectric-constant material (under the trade name GIGAFIL).
The company has written its own proprietary CAD programs to aid in various designs. Researchers
demonstrated progress in miniaturization by showing successive versions of two 900 MHz GIGAFIL
duplexers. The mobile version came down from 66 cc in volume and 154 gm in mass in 1983 to 3.9 cc and
20 gm, respectively, in 1996. The handheld version went from 9.5 cc and 30 gm in 1986 to 0.9 cc and 3 gm
in 1995 (and 0.5 cc in 1997).

The work on both dielectric block filters and on multi-layer functional substrates was particularly
impressive, both leading to miniaturized high-performance components. The latter starts out with thin strips

                                      Appendix D. Site Reports--Japan                                     127

of green ceramic piled in layers. One such device consisted of 21 layers; as many as 600 layers have been
contemplated, but not made. The fabrication steps are briefly stated as follows:
   mix materials
   de-air
   make sheets
   cut sheets
   punch via holes
   fill via holes
   add dielectric material + solvent + binder
   print inner electrode
   punch cavity
   stack
   press
   form grooves (for later breaking into separate modules)
   cofire
   inspect
   plate Au/Ni electrode
   print solder paste
   mount components
   solder
   break where grooved
   package and mark
   inspect
   pack and ship

In MIMIC product development, Murata uses a multilayer integration technology via multi-layer lamination.
The metal used is copper while the inner electrodes are developed by silk screen printing. All processes are
controlled by CCD. After the ceramics are fired, the layers are separated by creating small grooves. After
cofiring the circuits are inspected and are then plated using Au/Ni.

Two different types of material are used: one of low er=6.1 and the other of high er=25, for antenna and
component applications.

Functional integrated technology develops circuits that include antennas, filters, diplexers, baluns, couplers
etc. The European market needs the dual band front-end device for very small size phone. Murata has a
wire bonding technology for module development. Since late 1999, there is a flip-chip technology for
MMIC. SiGe HBTs are used for the CDMA amplifier.

For the European market, Murata is developing an Antenna Switch Diplexer (GSM/DCS) with a SW LPF
and switch diodes using LTCC. About 23 components are printed on 21 layers. The design is based on
magnetic and electric simulation, sensitivity analysis and monte carlo simulation for optimization of yield,
pattern lay out of multilayer circuit, and then trial production. The size of this component is 6.7 x 6.7 x 1
mm.

Filter technology goes to 2 micron thickness, which is expected to be further reduced in order to reach the
1 GHz mark. The transverse dimension may be as high as a few millimeters.

                                      Appendix D. Site Reports--Japan
128

Another aspect of Murata development went beyond the many steps from raw material to finished device,
namely the cooperation with and assistance to the end customer, which seemed to be quite close. For
example, Murata did not stop at the delivery to the customer of, say, capacitors for EMI (electromagnetic
interference) suppression, but also provided a large anechoic chamber to test the performance of the
customer's entire system against RFI (radio frequency interference).


FUTURE RESEARCH INDICATED

As on other visits, the Murata hosts had difficulty making long-range predictions 15, 10 or even 5 years into
the future. At least two WTEC study team members thought they detected two major trends besides the
constant research into better materials, devices, and circuits. One trend was the constant push toward 3D
micro-miniaturization, as evidenced here by the multi-layer construction. The drivers are smaller size, lower
mass, lower cost, and sometimes better performance (afforded by integration and the avoidance of
connectors and connecting 50-ohm cables). Research into new or better ways to do so might have a good
payoff perhaps several years away.

The other trend is different. It is the importance of close collaboration between system designer and
component developer. An example of such collaboration is the existence of a large anechoic chamber (the
WTEC panelists did not see it--it is in Yokohama) at a component manufacturer's plant. It seems not
unreasonable to speculate that device engineers need to be more knowledgeable of system needs, and system
engineers need to know more about devices. This goal could have a significant impact on the engineering
education.

                                       Appendix D. Site Reports--Japan                                        129

Site:                 NEC C&C Media Research Laboratories
                      Miyazaki 4-1-1, Miyamae-ku
                      Kawasaki, 216-8555
                      Japan

Date:                 1 June 1999

WTEC Attendees:       R. Pickholtz (report author), R. Rao, B. Mooney, W. Stark, N. Moayeri

Hosts:                Akihisa Ushirokawa
                      Minoru Shikada
                      Kojiro Hamabe
                      Kenji Takeda
                      Kazuhiro Okanoe
                      Hiroshi Furukawa
                      Kenichi Ishii

BACKGROUND

The Computer and Communications (C&C) Research Laboratories is an outgrowth of the original NEC
Research Laboratories, first established in 1939. The current structure was established in 1993 in response
to the convergence of the two disciplines. NEC ranks sixth and seventh in sales of C&C products. In 1993
sales were $36.85 billion, 35% of which was communications, 40% computer and 20% electronic devices.
The C&C Laboratories primary focus is in three main areas: computers, devices and networks wireless
systems span all three of these areas: At the center, the panel visited at Kawasaki, Kanagawa, there were
about 1,600 employees and a Research Institute 1,400 of whom were graduate engineers.

There are 13 laboratories and centers at the Central Research Laboratories in Kawasaki, Kanagawa, housed
in a modern complex. The C&C Media Research Laboratories, which the panel visited, is the largest with
300 people. Its three-fold mission is networking, computer systems, and terminals together with any
supporting system software. It is under the network mission that wireless lies along with Future Network
Architectures, ATM, Internet, Optical Networks, and Access Technologies (cables, fiber, wireless).

NEC also operates smaller R&D centers in Europe and the United States and a Research Institute in
Princeton.


SYNOPSIS

After introductions, an overview of the NEC R&D Group was presented with questions and answers. A
brief talk "Mobile Multiuser Wireless Networking with High Mobility and a Flexible System
Deployment"was presented describing the R&D mission. This vision, which would allow transmission
speeds close to 150 mbps and 10-20 km cell coverage was identified as "4th Generation." Specific research
topics included High-Speed Wireless LAN, Software Radio/RF circuits, concept, and network architectures.

Several laboratory tours followed, including interactive discussions with researchers about their projects.

Among the devices the panel viewed were a 2.5 GHz (Japan's ISM Band) testbed for a 25 Mbps W-LAN
using CSMA medium access protocol built on a card; a hardware testbed WCDMA including multistage
parallel, successive interference cancellation simulating 3 users in a multi-path Rayleigh fading channel
operating at currently envisioned 4.096 Mbps in a 5 MHz band; and two diversity branches plus four finger
RAKE receiver using soft VA decoding concatenated with (hard input) RS (36, 32;256). For multimedia

                                          Appendix D. Site Reports--Japan
130

use, it is envisioned that the higher power, high rate data users (256 kbps) would be cancelled from the
received composite. Performance curves were impressively close to theoretical limits.

Further discussions revealed that individual researchers believe that spatial processing/beam forming at the
base station will be very important for future wireless systems to reduce interference, power required, multi-
path. A major issue is propagation effects: shadowing and blocking in metro access. Mobile computing
will require a new mobile IP and, for various reasons relating to channel conditions, routing and handoff, re-
examining all the layers of the protocol stack will be needed. There is also a need to define user QOS and
the functional relationship between this ultimate QOS and the individual QOS parameters at each layer.


PROPOSED RESEARCH AREAS
     better smart antennas
     blind algorithms (standards free)
     DBF algorithms and implementation
     large aperture, large element systems
     interference mitigation
     Multi-User Detection (MUD)
     simple algorithms possible for handset
     optimization of cost-effectiveness measures
     QoS measures
     definitions that work
     functional relationships between levels
     optimization

POTENTIAL COLLABORATIONS

Kazuhiro Okanoe, Hiroshi Furukawa, Akihisa Ushirokawa

                                      Appendix D. Site Reports--Japan                                    131

Site:                 NEC Tsukuba Research Laboratories
                      34 Miyukigaoka, Tsukuba
                      Ibaraki 305-8501 Japan

Date:                 1 June 1999

WTEC Attendees:       T. Itoh (report author), J. Winters, M. Iskander, H. Morishita

Hosts:                Dr. Kazuhiko Honjo, Manager, Ultra High Speed Device Research Laboratory
                      Dr. Toshio Uji, Assistant General Manager, Optoelectronics and High Frequency
                           Device Research Laboratories
                      Dr. Masaaki Kuzuhara, Senior Manager, Kansai Electronics Research Laboratories
                      Dr. Kenichiro Suzuki, Principal Researcher, LSI Basic Research Laboratory, Silicon
                           Systems Research Laboratories

BACKGROUND

NEC is one of the world leaders in electronics and communication and has been subscribing to the concept
of C&C (Computers and Communication). This visit is for its Tsukuba Research Laboratory. NEC also
provided information on its Kansai Electronics Research Laboratories, which was represented by Dr.
Kuzuhara who made a special one-day round-trip from Otsu to Tsukuba for his presentation to the WTEC
panel.

NEC's capabilities concerning semiconductor devices have enjoyed a high reputation throughout the world,
particularly in the areas of compound semiconductor devices for optoelectronics and high frequency devices
and components.


SYNOPSIS

After welcome greetings from Dr. Honjo and the presentation by T. Itoh on behalf of the visiting WTEC
study team, Dr. Uji, as a senior executive, made a brief presentation about the corporate structure, R&D
operations, and organizational configurations of NEC. The R&D Group is responsible for the Technology
for the Day-After-Tomorrow, while the R&D operation of each business group looks after technology for
today and tomorrow. The R&D Group employs about 1,600 and works on multimedia systems/software,
C&C, functional devices, semiconductor devices, and materials/fundamentals at several locations in Japan
and abroad. R&D expenditure is 1% of NEC annual sales for the R&D group and 10% of NEC annual sales
for the entire company. Presentations were heard from the Optoelectronics and High Frequency Device
Research Laboratory (Dr. Honjo), Kansai Electronics Research Laboratories (Dr. Kuzuhara), and later from
Silicon Systems Research Laboratories (Dr. Suzuki on Microswitch).

The Optoelectronics and High Frequency Device Research Laboratories consist of the Ultra High Speed
Device Research Laboratory (Dr. Honjo) and three opto-electronics research laboratories. However, when
combined with the effort at Kansai Electronics Research Laboratory, the ratio of the effort on high frequency
devices is on the par with optoelectronics research. The Ultra High Speed Device Research Laboratory is
engaged in research on wireless devices, compound semiconductor digital/analog LSIs and electron device
physics. Kansai Electronics Research Laboratories consists of the Ultra High Speed Compound
Semiconductor Devices Group (crystal growth/process technology, device physics/simulation, low noise
microwave and millimeter wave devices, and high power microwave and millimeter wave devices and
millimeter wave MMIC) and the Semiconductor Photonic Devices Group. Tsukuba tends to emphasize
design and new materials, while Kansai emphasizes process technology and design. Another unique feature
is that Kansai Laboratories are co-located with a business unit for semiconductor manufacturing.

                                      Appendix D. Site Reports--Japan
132

RESEARCH AND DEVELOPMENT

Si MOSFET, E-HEMT and HBT (Dr. Honjo)

Si MOSFET

The use of CMOS grade Si is appealing for low cost wireless technology. NEC has developed Si nMOSFET
for high power amplifiers in GSM. Under class AB operation, the maximum PAE of a Si MOSFET
amplifier at 900 MHz is as high as 62% with output power of 27 dBm. MOSFET technology is an old
previous generation device with 0.6 m gate. Since the transmission line loss is high due to the substrate,
the amplifier design makes use of a conditionally stable device so that the amplifier is still unconditionally
stable (loss matching technique).

A new 0.18 m gate nMOSFET for Ku band operation was developed with fT of 50 GHz and fmax of 45 GHz.
In order to reduce the transmission line loss, two types of modified microstrip lines have been developed.
Both use polyimide layers as a low loss dielectric layer insert. In Type A, a microstrip is simply placed on
top of the polyimide layer that is in turn placed on the Si substrate through SiO 2 and SiON isolation layers.
This is a slow-wave type structure while Type B is a thin-film microstrip type with an Al layer insert in the
SiON and SiO2 layers between Si and polyimide. Since the long term stability of polyimide is uncertain,
researchers are considering BCB materials as well. A reasonable loss of 1 dB/cm was obtained. Both the
single-gate type and the cascade type amplifier were built with a gain of about 10 dB and a NF of 4 ~ 5 dB at
the Ku band.

GaAs HEMT

Future mobile wireless communications for multimedia will require high speed (> 20 GHz) and low power
PLL. To this end, a high speed and low power dual-modulus prescaler IC is needed. This was accomplished
with a new 0.1 m Double-Deck-Shaped gate (a two stage mushroom gate) GaAs E/D-HEMT with a
coplanar based MMIC with 1.6  0.8 mm size with 50 ohm on-chip termination.

High fmax (> 200 GHz) HBT Technology

In order to reduce the base resistance, selective regrowth was used so that base resistance was reduced to one
fourth. At the same time pseudomorphic InGaAs graded base was used. In this way, regrowth-performed
GaAs-based HBTs achieve low RbCbc leading to an fmax comparable to those of high-performance InP-based
HBT that have higher fT. With these device technologies, a 26 GHz HBT power amplifier module (two
device power combined) with 3.63 W and PAE of 21%, a 1W 35 GHz HBT power amplifier with PAE of
29%, a 60 GHz dynamic frequency divider, and a low phase-noise 38 GHz HBT MMIC VCO, were
fabricated.

Other Topics Discussed

NEC does not currently work on A/D and D/A for software radio.

SiGe HBT has not been developed in the research lab, but is produced in other divisions. The device tends
to have a high fT but a low to medium fmax due to high base resistance.

Researchers are working on a GaN device as the next generation workhorse. They obtained an fmax of 90
GHz using sapphire and SiC substrate.

Dr. Honjo believes that for wireless applications up to 100 GHz, InP cannot be considered as a next
generation device. This is because GaAs can cover up to 100 GHz while GaN can provide higher power.

                                      Appendix D. Site Reports--Japan                                     133

Power HEMT Mobile Communications and Millimeter Wave HEMT MMICs (Dr. Kuzuhara)

Power HEMT

The first HEMPT design is for Japanese PDC (TDMA) systems while the later design takes advantage of the
5 GHz bandwidth allowed by the Japanese government for 60 GHz systems. This is an attractive way to
develop mobile multimedia wireless applications.

For the new HEMT (both the depletion type and the enhancement type), RON is reduced and PAE increased
by low contact resistance and doped recess with the n+-GaAs layer. The enhancement mode device is
attractive, as it requires a single power supply. For PDC application of the E-mode device, the Ron = 1.6
ohm.mm and PAE was 67.6% with Pout of 1.15 W when Vd was 3.5 V. For W-CDMA applications of D-
mode HEMT, PAE was 54% with Pout of 570 mW at ACPR of 40 dBc at Vd = 3.5 V. PAE can be improved
with a low Pout of 20 mW (13 dBm) when an optimized Vd control by a DC-DC converter is used (similar to
the work by UCSD). PAE is increased to 21% from 8 % under such a low power output. This is due to the
fact that the reduced drain voltage brings the device into saturation.

Millimeter Wave CPW MMIC

The low dispersion and high isolation nature of the CPW is used for millimeter wave (60 GHz) MMICs for
potential wireless multimedia applications in conjunction with a flip-chip mount. In order to avoid gate
peeling and to increase reliability of the HEMT, SiO2 filling on both sides of the T-gate supports the gate.
The air gap for flip chip was determined in such a way that an EM simulator makes the effect of the ceramic
substrate (motherboard) negligible.

Other Issues Discussed

Dr. Kuzuhara emphasized the growing importance of antennas, particularly planar antennas integrated on the
ceramic substrate for low cost millimeter wave applications. Point-to-multi-point applications require
adaptive antennas.

MEMS Switch (Dr. Suzuki)

Dr. Suzuki presented a paper reporting on a project of low insertion high isolation silicon RF microswitches
on a glass substrate for satellite communication applications. Glass substrate is needed as this is a phased
array with a large aperture. Therefore, silicon substrate is not large enough. Each antenna feed unit is 5 mm
 5 mm, and eight element switches are used to achieve a phase increment of 22.5. The switch element is
made of single crystal Si with a double-hump configuration. One of the humps enables contact, and the
other permits electrostatic force generation. The humps are mechanically connected on a single arm but
electrically isolated by dielectric material in between. The voltage is 50 V, which must be reduced to less
than 20 V. The insertion loss measured was 0.2 dB at 30 GHz.


OBSERVATION

NEC presented very high level technical accomplishments and the WTEC panel's hosts were very open in
discussions. NEC has traditionally exhibited a high level of success, particularly in semiconductor devices
and applications. Therefore, there is great confidence, and researchers do not often fall prey to the "me-too"
attitude. The company appears ready for not only low-cost next-generation wireless, but also more future
looking millimeter wave applications beyond 60 GHz. Although its strength lies in semiconductor
technologies, NEC is well aware of other important issues such as on-chip antennas, self-packaging, etc. In
addition, there is a long history of developing products based on research. This is expected again in this
case. High performance devices alleviate difficulty in circuit design.

                                       Appendix D. Site Reports--Japan
134

Site:                  Nippon Telegraph and Telephone Corporation (NTT)
                       Wireless Systems Laboratory
                       1-1 Hikarino-oka, Yokosuka-shi
                       Kanagawa-ken
                       Japan

Date:                  2 June 1999

WTEC:                  J. Maurice (report author), T. Itoh, L. Katehi, J. Winters, D. Friday, M. Iskander,
                            L. Young, B. Mooney, (also present was Ms. Fumiko HAZAMA, serving as
                            interpreter when required)

Hosts:                 Dr. Hideki Mizuno, Executive Manager, Wireless Systems Laboratory, NTT Network
                            Innovation Laboratories
                       Mr. Masashi Shimizu, Deputy Executive Manager NTT Network Innovation
                            Laboratories
                       Dr. Masayoshi Tanaka, Executive Research Engineer, NTT Science and Core
                            Technology Laboratory Group
                       Dr. Shuji Kubota, Senior Research Engineer, Supervisor, Wireless Systems
                            Laboratory, NTT Network Innovation Laboratories
                       Mr. Toru Otsu, Senior Research Engineer, Supervisor, Wireless Network Control
                            Research Group, Wireless Systems Laboratory
                       Dr. Masahiro Muracguchi, Senior Research Engineer, Supervisor, Wireless
                            Communication Electronics Research Group, Leader, Wireless Systems
                            Laboratory, NTT Network Innovation Laboratories
                       Mr. Katsuhiko Araki, Senior Research Engineer, Supervisor, Satellite
                            Communications Electronics Research Group, Leader, Wireless Systems
                            Laboratory
                       Dr. Toshio Nojima, Senior Executive Research Engineer, Wireless Circuits
                            Laboratory Wireless Laboratories

BACKGROUND

The visit to NTT R&D Laboratory, Yokosuka Site, was very hardware-focused, with presentations by every
director of wireless communication activities except for one. Each department's focus and activities were
briefed, and Dr. Mizuno, executive manager and the panel's key host, represented the single absent member.
Representatives from the commercial side of NTT did not attend.

The technical presentations were followed by a variety of NTT-developed system demonstrations. These
were Cyber Communication Lab Group focused, because cyber-communications (mass media products and
technologies) is a Yokosuka site specialization.       NTT's Yokosuka site houses both the Cyber
Communications Laboratory Group and the Network Innovation Laboratories.

At NTT, R&D on advanced wireless communication technologies for transmission systems is grouped
according to whether it is (1) software-defined radio (SR) or (2) local information systems. Regarding these
larger categories, NTT explained in brief the following research areas (departments) within them:
     next generation satellite communication system & technologies (Dr. Otsu)
     3D MMIC technologies (Dr. Muraguchi)
     on-board satellite equipment (Dr. Araki)

                                       Appendix D. Site Reports--Japan                                    135

   antenna technologies (Dr. Mizuno)
   large deployable antenna technologies (Dr. Nojima)

These areas of research are reported upon individually in what follows, together with the introductory
overview NTT presented.

NTT employs over 3,000 people in three facilities. The staff at the Yokosuka site visited numbers about
1,000.


REPORTED ACTIVITIES, TECHNOLOGIES, AND DISCUSSION

Advanced Wireless Communication Technologies (Dr. Kubota)

As mentioned, R&D on advanced wireless communication technologies are grouped as follows at NTT:
   SR technologies
   local information system (P-POINTS)
Conventionally, radio technology is analog-specified, digital-circuit based, and fixed function. The
distinguishing feature of SR, on the other hand, is that SR is general-purpose-programmablea digital
circuit, but with software. SR is thus a multi-standard, flexible wireless system. It operates to and from a
multi-standard (PHS, PDC, AWA) terminals and base stations and features multi-mode operation, that is, a
seamless operation in multiple systems, bridging different standard wireless systems. This is because it is
based on adaptive transmission technologies, employing an adaptive antenna, adaptive modulation, coding,
RF frequency, and bit rate.

NTT's local information system is called "P-POINTS." The first "P" in "P-POINTS" is for "positioning,"
and "points" indicates the high positioning accuracy that is attainablewithin 10 m. The P-POINTS system
is configured as follows: P-POINTS links, by radio, to a PDA (personal digital assistant) equipped with a
PHS (personal handy system), which in turn links to a base station and, through an ISDN public network, a
host node. The following are parameters of the P-POINTS system:
   RF band: 2.42.5 GHz (ISM-band)
    modulation: /4-DQPSK

   bit-rate: 384 kbps
   transmission power: less than -10 dBm
   positioning accuracy: less (within) than 10 m
   features solar battery and storage battery

P-POINTS is a hybrid system employing SR. Its applications are for indoor and outdoor high accuracy,
seamless positioning. Deployment of its service area is by self-multiplication via a wireless network. A
schematic shown at NTT linked GPS satellite to PHS to very many P-POINTS (SR markers).

First & Next-Generation Multimedia (MM) Satellite Communication System (Dr. Otsu)

The purpose of the first and next-generation systems described below is to provide an interactive MM
satellite network service. The main schematic shown featured three key subsystems: (1) high-speed Internet,
(2) multicast communication, and (3) multicast transmission.

The first-generation MM satellite communication system is configured as follows: a central Earth station
(CES) uplinks to a communication satellite, the satellite links to an Earth customer station, and the customer
station back to the central station (CES) via either Internet or PSTN/ISDN (Public-Switched Telephone

                                        Appendix D. Site Reports--Japan
136

Network Integrated-Services Digital Network) links. The CES is the network control center. It consists of
an MPEG encoder, multiplexer plus scrambler, an ATM router, a video server, and guest workstations. In
the first-generation system, the satellite links to the user/customer with an antenna, PC, and TV at 30 Mbps.

First-generation satellite MM system parameters include the following:
     frequency is Ku band specified
     satellite channel is DVB compatible
     access scheme is TDM
     modem specification is QPSK-coherent demodulation
     clock rate is 21.096 MHz, with an information rate of 29.007 Mbps
     FEC is inner-coding specified with convolution encoding and Viterbi decoding (3/4)
     FEC outer-coding Reed-Solomon (188/204) specified
     multiplexing is ATM
     the earth center station antenna is 4.2 m diameter with a transmitter output of 45 W
     the earth customer station antenna is 50  75 cm diameter via a 10 Base-T PCI bus (receiver adapter PCI
      card includes DVB tuner function)

The second-generation system is a portable MM satellite communication system. By means of it, NTT will
expand the service area to where there is no available terrestrial link. The projected system configuration
consists of a communication satellite, a portable user terminal, a CES with a forward-link access server. The
user terminal will use the Ku band. It is portable and highlights the mobility of the user. (The Ku band
antenna can be atop a car, etc., and a video demonstration was given.) The user terminal also will be capable
of realizing bi-directional communication via satellite, and have flexible satellite backward high-speed link.
The user will not have to point the antenna at the satellite. The uplink (forward link) is SS-FDMA 9.6 kbps
(x 256) at 100 mW, and the backward link is TDM (8 Mbps).

3D MMIC Technology (Dr. Muraguchi)

The miniaturization of MMIC technology at NTT started 20 years ago. Ten years ago NTT started using
copper in its MMIC designs and devices, and now researchers have progressed considerably towards 3D-
interconnect technology that further improves performance, reduces chip size, and, hence, reduces cost.
NTT moved from the standard microstrip MMIC device to a uniplanar (2D) one with 1/5th the area for a
function and 1.5 times the 2D's depth. Under their new 3D MMIC technology, the same functionality is
achieved on 1/20th the area of 2D MMICS, and on 3 times the thickness. The chip consists of (1) thin-film
microstrips with narrow line widths (5-30 m) and narrow line-width spacings, (2) it has grounding and
shielding metal layers, (3) dielectric layers, and (4) ground wireslinking to logic, and all on a substrate.
The U-band single-chip down-converter measures 1.78 mm x 1.28 mm. It has a conversion gain of 0 dB +/-
1.5 dB and an image rejection ratio greater than 15 dB (at 42.5 GHz to 47.5 GHz). The K-band, Si-based 3D
MMIC has an 0.70 mm x 0.46 mm amplifier coupled with 0.46 mm x 0.42 mm mixer. The mixer is based
on analog circuitry (it is not digital). In heterodyne-down converting, it averages a -10 dB conversion loss in
the 10-30 GHz frequency band of the local oscillation signal.

Considerable cost savings are projected with the miniaturization of K-band Si 3D MMICS, in particular.
NTT showed a comparison chart of fabrication cost-saving projections for its Si masterslice MMIC. The
cost of Si masterslice MMIC is less than 1/10 the cost of conventional GaAs MMICs. (Additional
information on the matter: the GaAs 3D MMIC has 1/2 the cost, the GaAs masterslice MMIC has 1/2 to 1/4
the cost, while the Si masterslice 6%-12% the cost.)

In summary, these are the key features briefed: The area for a function is 1/3 to 1/20 that of conventional 2D
MMICs. The application frequency is improved up to 65 GHz. Using masterslice MMIC design

                                       Appendix D. Site Reports--Japan                                      137

methodology, the turnaround time from design to fabrication is less than 1/2 that of 2D MMICs. The simple
and parasitic-free MMIC design is compatible with CAD. The process is 3D interconnect technology using
6 metal layers with polyimide as the insulator. Further regarding the structure, it is based on 4 layers, of 10-
12.5 m thickness each, containing both lumped and distributed elements. The logic devices are GaAs
MESFETs and Si BJTs. The capability is (1) mixed-mode IC, (2) millimeter-wave Si MMIC, and (3) "radio
on a chip."

The first item of discussion addressed aspects of the MMIC structure. Although there is vertical isolation,
still problems still occur at high frequencies. Vias are used, but parasitics remain. NTT reported that it uses
a groundline at every layer to equalize the potential. Next discussed was NTT's BFN MMIC technology,
that is, MMIC technology that achieves beamforming. NTT has developed a 2.5 GHz-band BFN MMIC.
The input signal is split into 32 components. All components of the 32 amplitudes and phases can be
controlled individually. The dimensions of the MMIC are a mere 11 mm x 11 mm, and it can talk to a
satellite. The last technology item discussed was an "intermodulation distortion controller for HPA." A new
type of intermodulation distortion control circuit is proposed.

On-Board Satellite Communication Device Equipment (Dr. Araki)

From the provided schematic: Under beam-forming and control technology, high-gain antennas link together
to cover segments of a geographical area. Discussed was a large-scale antenna reflector with an active
phased-array feed. The active phased-array feed consists of (1) a small and lightweight beam-forming
network (BFN) that takes RF input and, with input from a beam controller (above), feeds (2) a high-
efficiency power-amplifier array that drives (3) the array of primary radiators. The BFN is MMIC-based.

A 2.5 GHz-band BFN-MMIC has been developed. Its input signal is divided into 32 signals, and the
amplitudes and phases of the 32 signals can be individually addressed and controlled. The dimensions of the
MMIC are 11 mm x 11 mm.

A high power amplifier with even-order-distortion control has been developed.

Antenna Technologies (Dr. Mizuno)

NTT antennas for high-speed wireless access include (1) rod-type printed antennas, (2) a multi-sector
monopole Yagi-Uda antenna, and the "smart antenna."

The rod-type are 6-sector, small-sized antennas for operation in the 25 GHz band. There are three types of
rod antennas. In each, microstrip antennas are printed on panels within the rod, the beam radiating out from
a cylindrical, disk-like radome atop it.

The multi-sector monopole Yagi-Uda antenna (MS-MPYA) consists of 2 very low profile 12- and 6-sector
units (120 mm and 60 mm diameters respectively) for operation in the 19 GHz band. The 12-sector unit
functions as the control module with a gain of 14 dB, and the 6-sector unit functions as the user module with
a 10 dB gain. Experimentally its beam-forming performance maps closely to calculated predictions of the
beam pattern.

The prototype smart antenna uses an adaptive technique for indoor high speed wireless communication
systems. In indoor propagation environments, multiple-reflected waves significantly degrade the
transmission quality in wideband wireless systems. However, NTT has demonstrated an adaptive array that
completely suppresses the multi-path waves, regardless of the incoming waves' numbers in the indoor
environment. By adaptively pattern controlling itself, the array suppresses the undesired long-delayed wave
effects, thus lowering BER and achieving improved transmission quality over pencil-beam antenna systems.
Also, compared with sector antennas, under same beam-width conditions, the Smart Antenna achieves lower
BERs (from 10-2 to 10-6, and a 38 Mbps data rate). This is because the Smart Antenna can steer and adapt for
not only the main beam direction but the null as well. Furthermore, by enhancing the desired signal by

                                      Appendix D. Site Reports--Japan
138

combining short-delayed waves compared with a sector antenna, the smart antenna's adaptive technique is
effective in miniaturizing base station antennas.

At present NTT's smart antenna is a prototype, awaiting the appropriate A/D converter and signal-processing
device to enable it as a commercial product.

(As an aside, Dr. Itoh, at this point, introduced the UCLA-developed quasi-Yagi-Uda antenna, which was
reported during an antenna propagation conference in July 1999, and he briefly showed its data, etc.)

Large Deployable Antenna Technologies (Dr. Nojima)

NTT has developed several deployable on-board antennassolid, wire mesh, and inflatable. The current
non-inflatable mesh-structure model has seven modules and a 10 m diameter and weighs about 80 kg. The
target for the future has 14 modules, with a diameter of approximately 14-15 meters, and weight of 120 kg.
The panels of this type fold out in a deployment sequence. This technology was successfully transferred to
NASDA, Japan's space agency. An on-site anachoic test chamber is available for testing the structures. An
anachoic chamber is available at another NTT facility, as well. The problem is the long focal length
required.

Topics of discussion included the inflatable structure itself. To form a reflector plane for the inflatable
structure, NTT sees an inflatable polymer-based film as the most promising for realization of this.


TECHNOLOGIES IMPORTANT FOR BOTH ANTENNAS AND THE ON-BOARD SATELLITE
COMMUNICATION EQUIPMENT

Key NTT Technologies for ETS-VIII (Mr. Shimizu)

The Engineering Test Satellite (ETS) Experiment is a series of seven testing and experimentation satellites
aimed at developing common-base communication technologies. The series is produced by NASDA,
Japan's NASA organization. The series ETS-VIII will be launched in 2002.

ETS-VIII will establish and verify the world's largest geostationary satellite bus technology. It features 10-
meter-plus deployable antennas with phased array feeds and is an advanced 3-ton-class spacecraft bus with
the world's largest and most advanced large-scale deployable reflector. It will enable technology for mobile,
multimedia audio/data communications with CD-level quality sound and image transmission from hand-held
terminals. These will be similar to popular cellular phones.

The ETS series is a big national project with many large companies involved to cooperate and implement it.
The relationship between NTT and NASDA is more than "just business." NTT participated in the ETS-V,
ETS-VI and ETS-VII, and ETS-VIII projects; NTT's mission objectives are (1) to provide the beam forming
network (BFN) component technology and (2) to assist in the analysis for deployable antenna technology.
As mentioned in a previous section, NTT's technology for BFN uses monolithic microwave integrated
circuits (MMICs). NTT also developed software that calculates precise deployment positioning motion
taking into account the elasticity of the truss and the cable structure. Key NTT technologies for ETS-VIII
can be summarized as (1) NTT designed the subsystem for ETS-VIII and (2) NTT provides the technology
for BFN and large deployable antennas in Japan.

                                      Appendix D. Site Reports--Japan                                    139

Future Applications and Important Research Areas

Advanced 3D MMICs & Smart Antenna technologies

The following were among those items demonstrated:
   super high-definition TV
   Cyber-bookan NTT-developed, Microsoft-marketed product featuring multimedia information search
    capability
   video panorama & video clipping (media creation, contents handling, etc., also see below)
   PHS Wristwatch
   voice-recognition electronic secretary

The demonstrations highlighted the focus of the particular facility visited at Yokosuka, that is, highlighted
was the information-based research areas of the Cyber Communications Laboratory Group housed there.
This group performs R&D of service foundations and solutions technologies and cooperates in joint projects
focusing on various software servers, terminals, etc., related to business-oriented information sharing. R&D
encompasses essential technologies as content creation, support technology, media technology, database
technology, etc., which contribute to the advancement of business-oriented information sharing.

Other research areas of the Cyber Communications Laboratory Group include the following:
   multimedia terminals, including home terminals, next-generation public terminals, and integrated
    environments for telecommunication and broadcasting
   multimedia communication, including Internet video services and medical-imaging systems
   intelligent media, particularly data mining, translation, and archiving
   media creation, meaning video synthesis, video interpretation, video interface, and media security
   cyberspace interface, including "high reality," storage, IC cards, sensing, and field-use media

Also at the Yokosuka site are the Network Innovation Laboratories. As suggested, this organization does
R&D on network systems based on cutting-edge telecommunications methods. They were represented at the
site visit.

                                      Appendix D. Site Reports--Japan
140

Site:                 NTT DoCoMo, Wireless Laboratories
                      3-5 Hikarino-oka
                      Yokosuka, Kanagawa 239-8536
                      Japan

Date Visited:         2 June 1999

WTEC Attendees:       R. Pickholtz (report author),T. Ephremides, T. Itoh, L. Katehi, R. Rao, W. Stark,
                      J. Winters, D. Friday, M. Iskander, J. Maurice, N. Moayeri, B. Mooney, H. Morishita,
                      L. Young

Hosts:                Toshio Nojima
                      Nobuo Nakajima
                      Fumiyuki Adachi

BACKGROUND

NTT DoCoMo is the largest provider of wireless services in Japan. The R&D Center was established in
1998 to do R&D in mobile wireless technology projects. It is now housed in an ultra-modern facility in the
center of Yokosuka Research Park (YRP), which also hosts many other high technology wireless companies
such as Nokia, Motorola, Lucent, and Ericsson. The companies in the park employ about 2,400 staff. The
goal is to become a Japanese "Silicon Valley" for wireless.

The DoCoMo R&D facility is the largest among these and employs about 600 technical staff. The complex
contains a large anechoic chamber and extensive multimedia facilities. The missions of the R&D center are
associated with three laboratories: wireless, multimedia, and networks. DoCoMo covers all aspects of
wireless including cellular, pagers, satellite systems and aeronautical radio. Although the R&D center
belongs to the central headquarters, the various component companies of DoCoMo share the R&D costs.

The current and continuing projects include, but are not limited to IMT 2000, new W-CDMA systems, etc.
NTT DoCoMo researchers have begun to study fourth generation (4G) systems. Among the general goals is
to make wireless terminals lighter, smaller, lower in power consumption, and able to provide high quality
multimedia information and capable of performing in embedded systems.


SYNOPSIS

A general overview of DoCoMo R&D was provided by Dr. Nobuo Nakajima and Dr. Nojima gave a
presentation "R&D Plan for 4th Generation Mobile Communication Systems." The vision is that 4th
generation systems will migrate from 3rd generation systems IMT-2000 and the various wideband wireless
LANS to provide both high mobility and bit rates exceeding 10 Mbps to meet the next generation Internet
capability wirelessly at lower cost.

The typical bit rate objectives for the fourth generation is >10-20 Mbps for indoor and pedestrian use and >2
Mbps for vehicular wireless use. Because of the population density of urban areas and the requirements for
nationwide service, a seamless picocell/microcell system is expected to be deployed. It may require dual
operation with IMT-2000. To achieve higher data rates, migration to higher RF bands will likely occur.
This increases path and circuit loss dramatically. Thus smart, adaptive arrays will be necessary. In addition
there may also be wireless and optical fiber entrance links from the micro or picocells to the base station.
There are tradeoffs in the access/modulation methods that require study: CDMA, for example, raises such
issues as width, multicarrier possibilities, high speed RAKE and Power Control, etc. OFDMA issues are
amplifier efficiency and linearity; and with TDMA, very high speed equalizers are an issue. Considerable
emphasis is being given to adaptive arrays to provide high gain to cut down the path loss, reduce

                                      Appendix D. Site Reports--Japan                                    141

interference, and minimize multipath. Research requires better tracking algorithms, compact designs, and
lower cost. One approach being studied to reduce size and costs of microcells is to use optical RF signals so
that all the complex tasks are taken back to the main base station. A principal additional attraction of that
method is air-interface independence since the active RF signal is passed to the main base station without
digital processing.

The same principle may be applied using a millimeter wave wireless access link for quick, inexpensive
deployment. Finally, software radios would allow greater flexibility, but research is needed on high speed,
low power DSPs and tunable, inexpensive RF circuits.

A tour of the labs revealed a working hardware demonstration/simulation for transmitting a 2 Mbps video
using 20 MHz CDMA through a fading channel at 100 km/hr.

A second demonstration showed a two-way mobile video system with 2 Mbps forward video and 384 kbps
reverse link. Since this project is now four years old, H.261 was used, but MPEG 4 is intended. This link
also provided 2-way voice. It also was a 20MHZ CDMA, fading channel with dual antenna and RAKE
diversity. There were no additional users in the system being demonstrated and the pictures were quite good
with no artifacts or apparent "noise".

WTEC panel chair, Dr. Anthony Ephremides, gave the WTEC presentation and vice-chair, Dr. Tatsuo Itoh,
described the views presented at the March 1999 workshop by various U.S. companies.

Finally, Dr. Fumiyuki Adachi gave a presentation entitled "W-CDMA: Performance Evaluation and Future
Enhancement." He described the phenomenal growth of the cellar market in Japan (>35% and the emerging
potential of wireless multimedia that is driving the need for 3G).

For IMT-2000, the research phase ended in 1996, and field tests will be concluded this year. Dr. Adachi
described the ongoing field tests, which incorporate advanced receivers including multistage interference
cancellation and adaptive antenna arrays forming both beams and nulls. Allusions were made to turbo
coding as well, but this was not stressed. Dr. Adachi responded openly to detailed questions about the
character and the performance of the interference cancellation scheme being used including a comparison of
theory, simulation, and actual measurements.


POTENTIAL COLLABORATORS

Dr. Fumiyuki Adachi

                                      Appendix D. Site Reports--Japan
142

Site:                 Tohoku University
                      Research Institute of Electrical Communication
                      2-1-1 Katahira, Aoba-ku
                      Sendai, 980-8577
                      Japan
                      http://www.riec.tohoku.ac.jp/

Date Visited:         3 June 1999

WTEC Attendees:       J. Winters (report author), M. Iskander, T. Itoh, L. Katehi, D. Friday, L. Young

Hosts:                Dr. Kazuo Tsubouchi, Professor
                      Dr. Kazuya Masu, Associate Professor
                      Dr. Hiroyuki Nakase, Research Associate

BACKGROUND

The Research Institute of Electrical Communication was established in 1935 for research in the areas of
microwaves, ultrasonics, magnetic recording, optical communication, acoustic communication,
semiconductor devices, and information theory. The institute is divided into three divisions: Brain
Computing, Materials Science and Devices, and Coherent Wave Engineering. The WTEC panel visited the
Acoustoelectronic Integration Engineering subsection of the Coherent Wave Division, which is headed by
Prof. K. Tsubouchi. This group has 4 Ph.D.s, 9 masters, and 4 bachelor students, along with 5 researchers
and 4 visiting researchers.


SYNOPSIS

Prof. Tsubouchi described the institute's main research activity, "Tele-Pad." Tele-Pad is a personal
multimedia terminal, which communicates voice, data, and images with high reliability and distributed
switching. Research is on a Tele-Pad system based on what was referred to as SS-CDMA (spread spectrum -
code division multiple access technology). The system operates with a 26 MHz bandwidth with up to a 2
Mbps data rate using microcells of up to 150 m in radius and pedestrian users. The main research challenge
being addressed by this group was the implementation of the correlator. Three different correlator structures
were presented, including the sliding correlator, matched filter, and convolver.

A ZnO/Si SAW convolver developed by this group has been implemented by Clarion for use on the uplink.
For the downlink, an aluminum nitride SAW matched filter was developed. The entire SS-CDMA system
was implemented on a PCMCIA card, which was commercially available in April 1999.


DISCUSSIONS OF FUTURE APPLICATIONS AND ISSUES

Although the research presented a novel approach to wireless multimedia communications, the main focus of
discussion was on research funding and the interaction with industry. This was the WTEC study team's only
visit to a university, and this university was chosen because it has been very effective in working with
industry and transferring technology from university research into industry.

At Japanese universities, there are several research funding possibilities. These include the Grant-in-Aid for
Scientific Research from the Ministry of Education, Science, Sports and Culture and the New Energy and
Industrial Technology Development Organization (NEDO) grants. In 1998, Professor Tsubouchi obtained
research funding through NEDO. NEDO provides research funding from the government to universities for
initial and basic research and development programs for industrial technology in areas in which the private

                                        Appendix D. Site Reports--Japan                                         143

sector is reluctant to undertake such research because of the risk in commercialization. Researchers in
industry propose research to the evaluation committee of NEDO, which checks funding sources and matches
funding sources with researchers.

Funding is provided for individual as well as group research. Funding is provided for a period of 3 to 4
years. For individual type, one to five million dollars would be provided, usually for basic research. For
group research (up to 5 people, some perhaps in industry), one to ten million dollars would be provided,
usually for applied research.

In terms of technology transfer, Prof. Tsubouchi stated that they had a 70% success rate in transferring
technology to industry. This was attributed to their visiting researcher program. With this program,
researchers from industry visit the institute for 2 years.

A company provides two to four researchers, with each researcher spending the first year studying at the
university and the second year working on technology transfer. This works because the researchers have a
commitment from the managers at their companies for the research projects to continue for 2-5 years, with
the companies gearing up for the technology transfer while the researcher is at the institute. Thus when the
researcher returns to industry, the company is set up for the new technology.


CONCLUSIONS

This institute provided a working example of how universities and industries can work together for effective
technology transfer. Long-term (3-4 years) research funding from the government provided for a stable
research environment, and the use of visiting researchers from industry aided in technology transfer.
However, for this transfer to be effective a long-term (2-5 years) commitment from individual companies
was required.


REFERENCES

Tsubouchi Lab. in 1999, viewgraphs.
Introduction to NEDO (brochure).
Tsubouchi, K., and K. Masu. "Wireless multimedia: SS-CDMA technology." Proceedings of International Symposium
    on Future of Intellectual Integrated Electronics. Presented March 14-17, 1999 at the Sendai International Center,
    Sendai, Japan. pp. 259-268.

                                       Appendix D. Site Reports--Japan
144

Site:                  Toshiba Corporation
                       Digital Media Equipment Systems & Services Company
                       1-1, Asahigaoka 3-chome, Hino City
                       Tokyo 191-8555 Japan

Date Visited:          31 May 1999

WTEC Attendees:        T. Itoh (report author), L. Young, W. Stark, N. Moayeri

Hosts:                 Mr. Shigekazu Hori, Deputy General Manager, Mobile Computing &
                             Communications Development Center
                       M. Ishibe, in charge of silicon technology
                       N. Sugi, in charge of systems hardware
                       T. Hirose, in charge of software
                       S. Saito
                       T. Saeki

BACKGROUND

Toshiba is one of the largest enterprises in Japan engaged in worldwide operation. It had net sales of $48
billion in 1998. Toshiba operates many research, development, and manufacturing sites and organizations
all over the world. Recent reorganizations have streamlined operations.


SYNOPSIS

Mr. Hori explained the operation of this organization and the work on system LSI and terminals
developments for GSM, W-CDMA, and wireless access. He provided interesting statistics quite different
from the United States in terms of the use of the wireless handset. In Japan, ~ 35% of wireless traffic is data,
as opposed to 5% in the United States. However, within this rate, 80% is short message service and digital
data transfer; and only 20% is PC-based data transactions. This is largely due to cultural specifics among the
younger generation. PHS systems are more aggressive for data service. Toshiba has recently introduced a
handset called TEGACKY (Te Ga Ki means handwriting) that is a pen-based no-voice handset. This is used
frequently even in crowded trains and subways to transmit handwritten messages.

Toshiba is working on products for W-CDMA to be introduced in early 2001.

Researchers are also working on fixed wired systems similar to LMDS at 24 GHz and 28 GHz (with 200
MHz bandwidth).


DISCUSSIONS OF FUTURE APPLICATIONS AND ISSUES

Mr. Hori asked his staff to prepare some responses to the WTEC questionnaire "Wireless Communication
Technology Issues and Questions." Questions and Mr. Hori's responses follow:

What are the important emerging applications for wireless communication over the next 5, 10, and 15 years
in the following areas?
     personal communications? Internet access, mail communication, information access, other multimedia
      contents service, Karaoke, motion video, TV phone, stereo (music and comical story telling), weather
      forecast, position information, electronic match making
     automotive applications? access to the Internet, mail, and computer from a moving vehicle, conversion
      of visual information to audio so that a driver can concentrate on driving

                                      Appendix D. Site Reports--Japan                                   145

   mobile Internet service? Internet commerce, ticket service, Internet phone
   fixed service?

What technologies will be important for wireless communications in 5, 10, and 15 years to satisfy these
applications?
   low cost, small size, low power (low voltage/low current), and system LSI
   data interface hard/software (USB, BT, etc.)
   man-machine interface (Browsers such as C-HTML and WAP, input/output devices such as LCD, keys,
    headset, microphones, speakers)
   anti-fading technology, error correcting technology, QOS
   world standardized protocols, software downloading
   high speed CPU, DSP, and other MPU technologies
   memory technology  high speed, on-chip, high integration, FROM
   automatic interpreter: voice synthesis, recognition, and conversion
   low cost (including terminals and services)
   all types of securities

Can conventional wireless communication technologies meet the requirements of these applications in 5, 10,
and 15 years?
   It is believed that the fundamental technologies are already in development or in conceptual stages.
    However, further advances as described above are continuously needed. Also, some problems such as
    standardization are not resolved. The patent issues are also of great concern.
   The most needed technologically is the optimization of the terminal under different environments. The
    difficult environments are urban and suburban areas and the base station area and sector. Also,
    developing the terminals with new technology/new system should be considered while interoperability
    with an existing communication system is maintained.
   The key technology lies in the LSI chip set. The tradeoff on the algorithm and power consumption is
    affected by the miniaturization of the LSI. This is not directly but deeply related to wireless
    communication technology. The weight and capacity of the batteries are also important.

Is a major change expected in the leading technologies used for wireless communication in the next 15
years?
   Renovation of the realization methods of the terminal corresponding to the application is expected. For
    instance, an ultra-thin card type radio is needed for data communication, a low power liquid crystal for
    visual terminals, and a protocol processor for multimode operation.
   Technologies to realize antenna-less terminal
   High density packaging: bare chip

What are the prospects for breaking the bottlenecks?
   Bandwidth
    -   For Terminals: renovation of anti-spurious/EMC technology, wideband receiver, low distortion
        transmitter
    -   For Wireless systems: cell structure/base station allocation, optimization of power control and
        adaptive bandwidth use technology

                                        Appendix D. Site Reports--Japan
146

     Channel loss (fading, interference)
      -   Learning by the moving speed of the terminal, location of use and user habit
     Portability
      -   Miniaturization, low power techniques, operability
     Interoperability
      -   Improvement of wireless circuits, optimization/multimode of protocols, high gain/high performance
          antennas

Mr. Hori provided the following observations:
     Instead of a smart handset (adaptable to different operating wireless systems), he has indicated a need to
      study smart base stations in which the base station recognizes the handset type and adjusts itself to the
      protocol and the system for which the terminal designed. (This is believed to be cumbersome at least at
      this time.)
     In terms of frequency, he considers that 4 GHz and 5 GHz would be needed for mobile access while 24,
      28, 30, and 60 GHz would be needed for fixed wireless service. He also pointed out that in the IP
      application, sophisticated architecture to decrease the packet overhead should be developed.
     He is concerned about a significantly reduced level of research on materials and devices. Nothing new
      has appeared recently except for Si, GaAs, InP, and SiGe in the materials and no new device structures
      after HBT and HEMT. He would like to see investigations of new junction structures.

CONCLUSIONS

The future technological direction at this site seems to be significantly influenced by cultural aspects in
Japan. Toshiba has tried new applications and products to fit the Japanese market. In addition, Toshiba
would like to mix the software/system issues with hardware. The company insists that mobile IP will be the
key technology in 3G wireless communication.

                                       Appendix D. Site Reports--Japan                                        147

Site:                  Yokosuka Research Park (YRP)
                       CRL (Communications Research Laboratories)
                       3-4, Hikarino-oka
                       Yokosuka, 239-0847
                       Japan

Date Visited:          4 June 1999

WTEC Attendees:        A. Ephremides (report author), T. Itoh, R. Rao, J. Winters, N. Moayeri, M. Iskander,
                            B. Mooney, D. Friday, J. Maurice, L. Young, H. Morishita

Hosts:                 Dr. Shingo Ohmori
                       Dr. Yoshihiro Hase
                       Dr. Masayuki Fujise
                       Dr. Hiroyo Ogawa

BACKGROUND

The Yokosuka Radio Communications Center, which includes the visited Communications Research
Laboratory (CRL), is under the Ministry of Posts and Telecommunications and is housed in the Yokosuka
Research Park (YRP), an extensive facility in which many government and private industry laboratories and
centers are located. The mission of CRL is to work jointly with industry and universities on applied research
projects in the area of mobile communications. It operates on an annual budget of $32.4 million, which is
18% of the total budget of the parent Radio Communications Center.

Projects are selected on the basis of submitted joint proposals that are evaluated by a Research and
Development Committee consisting of representatives from industry, academia, and the Ministry of Posts
and Telecommunications.


DISCUSSION

The visit commenced at 2:30 p.m. with a presentation of the goals of the WTEC study team by panel chair,
Dr. A. Ephremides and the findings of the U.S. industry workshop of March 15, 1999, by panel vice-chair,
Dr. T. Itoh.

Dr. S. Ohmori, Director of the CRL, then proceeded to give an overview of the laboratory and its activities.
These can be classified into two categories: basic technologies and mobile communications. Within the
latter category there are currently three groups. The panel was briefed on the activities for each one of these
in detail by their respective executive managers.

Millimeter Wave Applications (Dr. M. Fujise)

The main project in this group is the communications support of an Intelligent Transportation System (ITS).
This is a large project in which 22 organizations are participating (including Motorola, Samsung, and Nokia,
in addition to Japanese organizations). The objective is to provide inter-vehicle communications in an
intelligent transportation system. The envisioned architecture consists of control base stations that are
connected to a backbone network and also via optical cable to local base stations that are in turn connected to
vehicles via wireless links in the 36/37 GHz range.

One of the objectives in the CRL group is to simplify the air interface on the vehicles via the radio-over-fiber
concept that requires the conversion between the millimeter wave and its optical counterpart so as to
interconnect the control base station with the local base stations via fiber cable. The local base stations are to

                                     Appendix D. Site Reports--Japan
148

be deployed along highways, so that, in effect, the system will implement a "road-to-vehicle"
communication concept.

Multimedia Wireless Access Systems (Dr. H. Ogawa)

The principal activity of this group is its participation in the Multimedia Mobile Access Communications
(MMAC) Promotion Council, a conglomerate established in 1996 to coordinate and promote broadband
mobile communications in Japan. It aims at speeds of 1-150 Mbps for mobile users (at any speed) and at
100 Mbps - 10 Gbps (Broadband MMAC) for mobile users at moderate speeds.

In the former case the group has been working on adaptive array antennas, OFDM techniques, and
propagation measurements and modeling (as well as the definition of standards for mobile access). In the
latter case, it has contributed to the development of a 156 Mbps video transmission WLAN that works for
slow-moving users. Again, the focus is on spatial diversity, high speed modulation/demodulation methods,
access control, and propagation. In addition, there is ongoing research on the use of the 60 GHz band. This
work is proceeding with the cooperation of seven Japanese companies. The group has participated in other
international efforts along similar objectives, such as ACTS, SAMBA, and MEDIAN. The intended
applications include in-house communication, outdoor systems, and wearable systems (such as eyeglasses).

Broadband Wireless Access Systems (Dr. Y. Hase)

The main activity reported in this group relates to SKYNET, an ambitious wireless network concept that is
envisioned to consist of platforms (balloons) at stratospheric heights and kept almost stationary by solar-
powered propellers that are interconnected via optical links and communicate with terrestrial users at radio
or microwave frequencies. The project aims at the implementation of such a system by the year 2007. It is
anticipated that by placing the platforms at the 22 km altitude, a total of 15 such airships will suffice to
provide full coverage of Japanese territory.

The SKYNET system is envisioned to provide a variety of services, some stand alone and others
complementary to those provided by other systems such as IMT-2000, 4th generation mobile, etc. It is an
alternative to terrestrial MMAC systems and to satellite systems (such as Iridium and Teledesic). Rates in
the 25-156 Mbps range are envisioned at arbitrary automobile speeds. Proof-of-concept demonstration is
anticipated in five years.

Current research at CRL concentrates on on-board antenna design and on frequency allocation.

Following these presentations, there were brief demonstrations of video-transmission at 156 Mbps and at
pedestrian speeds by laboratory personnel.


CONCLUSIONS

The CRL facility is focusing primarily on applied research and yet is involved in rather long-term projects.
The technologies it emphasizes include wireless networking (SKYNET project), with important similarities
to ad-hoc networks and to satellite systems, and multimedia, high-speed wireless transmission (including
millimeter wave over fiber). The main research areas are spatial diversity, access control, propagation at
new frequencies in the spectrum, and standardization.

                                                                                 149


APPENDIX E. GLOSSARY


ACTS                   Advanced Communication Technologies and Services [Programme]
                       (European advanced communications R&D program) (also, Advanced
                       Communications Technologies Satellite, NASA)

ADC/DAC                analog-to-digital converter/digital-to-analog converter

AIr                    advanced infrared wireless (IBM)

ARQ                    automatic repeat request

ASICS                  application-specific integrated circuits

ATM                    asynchronous transfer mode

AWA                    advanced wireless access (NTT site report)

A WG N                 additive white Gaussian noise

BER                    bit error rate

BFN                    beam-forming network (NTT site report)

bps                    bits per second (also Mbps, kbps, etc.)

BPSK                   binary phase shift keying

BS                     base station

BSC                    base station controller

BSPLAN                 tool for mobile base station planning (KDD)

BT                     bipolar transistor

CAD                    computer-aided design

CATS                   CDMA Automated Test System

CATV                   cable television

CDMA                   code division multiple access

CES                    central Earth station (NTT site report)

C-HTML                 compiled hypertext markup language (file extension)

CMA                    constant modulus algorithm

CMOS-RF                complementary metal oxide semiconductor radio frequency

CPU                    central processing unit

                   Appendix E. Glossary
150

CPW       coplanar wave-guide

CRT       cathode ray tube

CSPLAN    tool for cellular and microcellular planning (KDD)

DBS       digital broadcast system (also direct broadcast satellite)

DECT      digital enhanced cordless telecommunications

DPSK      differential phase shift keying

DRO       dielectric resonator oscillator

DS-CDMA   direct sequence code division multiple access

D SP      digital signal processor

EH-DCR    even harmonic type direct conversion receiver (Mitsubishi Electric)

EIR       equipment identification register

EM        electromagnetic

EMI       electromagnetic interference

EMT       electron mobility transistor

ESPRIT    estimation of signal parameters using rotational invariance techniques
          (chapter 6) (also, European R&D program, appendix C)

ETSI      European Telecommunications Standards Institute

FDD       frequency division duplex

FEC/ARQ   forward error correction/automatic repeat request

FET       field-effect transistor

FFT       fast Fourier transform

FPLMTS    future public land mobile telecommunications system

GMSK      Gaussian-filtered minimum shift keying

GPRS      general packet radio service

GPS       global positioning system

GSM       Global System for Mobile Communications (wireless standard used in
          Europe)

HBT       heterojunction bipolar transistor

HEMT      high electron mobility transistor

HEO       high earth orbit

                  Appendix E. Glossary                                      151

HFR      high frequency radio

HPA      high power amplifier

HTML     hypertext markup language

HTS      high temperature superconductors

IC       integrated circuit

IETF     Internet Engineering Task Force

IN       intelligent network

IP/ATM   Internet protocol asynchronous transfer mode

ISDN     integrated services digital network

ISM      industrial-scientific-medical frequency band (902-928 MHz, 2400-
         2483 MHz, 5725-5780 MHz)

ISO      International Standards Organization

ITU      International Telecommunication Union

ITU-T    International Telecommunication Union--Telecommunications
         Standards Sector

LAN      local area network

LED      light emitting diode

LEO      low earth orbit

LMDS     local multipoint distribution system

LNA      low noise amplifier

LSI      large scale integration

MAC      media access control

MBE      molecular beam epitaxy

MCM      multichip module

MCPA     multicarrier power amplifiers

MEMS     micro-electro mechanical systems

MEO      middle earth orbit

MESFET   metal Schottky FET

MIMO     multiple input, multiple output

MMAC     multimedia mobile access control

                 Appendix E. Glossary
152

MMIC    millimeter/microwave monolithic integrated circuit

MMSE    minimum mean square error

MPLS    multiprotocol label switching

MU      multiple user

MUD     multiuser detection

OEM     original equipment manufacturers

OFDM    orthogonal frequency division multiplexing

OMG     Object Management Group (oversees CORBA)

OQPSK   offset quadrature phase shift keying

OS      operating system

OSI     open systems interconnection (architecture)

OTD     orthogonal transmit diversity (Ericsson)

PAE     power added efficiency

PCCS    ported coaxial cable system

PCS     personal communication systems

PDA     personal digital assistant

PDC     Personal Digital Cellular System (wireless standard in Japan)

PHEMT   pseudomorphic HEMT

PHS     personal handy system (Japan)

PLL     phase locked loop

PNNI    private network to network interface

PS      positioning system

PSTN    public switched telephone network

QoS     quality of service

QPSK    quadriphase shift keying

RF      radio frequency

RFIC    radio frequency integrated circuit

SAMBA   System for Advanced Mobile Broadband Application

SAW     surface acoustic wave (filter)

                  Appendix E. Glossary                                  153

SOI      silicon-on-insulator

SWDR     software defined radio

TCXO     temperature controlled crystal oscillator

TDD      time division duplex

TDMA     time division multiple access

TINA-C   Telecommunications Information Networking Architecture Consortium

TMF      TeleManagement Forum (industry group)

TOA      time of arrival

UMTS     universal mobile telecommunication system

USB      universal serial bus

UWCC     Universal Wireless Communication Consortium

VCO      voltage controlled oscillator

VNA      vector network analysis

V SA T   very small aperture terminal

WAP      wireless applications protocol

WLAN     wireless local area network

Y IG     yttrium-iron-garnet (used for tunable filter)