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.

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.


Published: July 2000; WTEC Hyper-Librarian