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 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.


Published: July 2000; WTEC Hyper-Librarian