NTT DoCoMo Touts W-CDMA For Next Generation Mobile Telecom
System expected to be available for public use in Japan by 2001Convenient, on-the-go access to the wide range of multimedia services anticipated for the 21st century - including dynamic video, voice, fax, data transmission, and universal Internet access - requires the implementation of an advanced mobile communications system.by Kenji Maruo With an eye on being first in mobile multimedia services, NTT Mobile Communications Network, Inc. (NTT DoCoMo), Japan's leading mobile telephone operator, is accelerating development of a wideband code-division multiple access (W-CDMA) system. The expanded bandwidth of W-CDMA will enable carriers such as NTT DoCoMo to offer numerous special features. These include: ¥ Variable-speed, multi-rate transmission capability, which will enable a single carrier to satisfy a wide range of needs. High-resolution video transmission, Internet connectivity, and voice, fax, data communications, for example, will all be possible at speeds of up to 2 M bps. ¥ Improved transmission quality, roughly equivalent to that of ISDN (integrated services digital network lines). W-CDMA offers unique encoding that allows multiple users to share radio channels while at the same time reducing the effects of noise, interference and reception level variations. ¥ Lower power consumption for mobile transmissions, thanks to new TPC (transmitter power control) functions. ¥ Increased transmission capacity thr-ough statistical-multiplexing enabling more efficient use of the frequency spectrum. ¥ Universal access by means of an Advanced Intelligent Network (A-IN), which would offer multimedia communications capability on a worldwide scale. W-CDMA is currently the leading candidate for the world's next (third-generation) mobile communications system. W-CDMA fully satisfies the requirements established in the International Mobile Telecommunications 2000 (IMT2000)/ Future Public Land Mobile Telecommunication System (FPLMTS) by the International Telecommunication Union (ITU). [For more on this, see Noriko Takezaki's article "The Next World Standard for Mobile Communications?" in our November 1997 issue.-Ed.]
Field trials underway The R&D Center is equipped with the most up-to-date experimental telecommunications facilities, including a radio "darkroom" and image and voice evaluation room. NTT DoCoMo has consolidated its 300-member research and development staff, which previously had been scattered at eight different laboratories throughout Japan, into the new center for faster and more efficient R&D activities. Plans call for the NTT DoCoMo R&D staff to be expanded to some 400 researchers by year's end. In October of last year, NTT DoCoMo successfully demonstrated a 2M-bps transmission in a W-CDMA field trial, which followed a June 1997 test of W-CDMA at Asia Telecom Ô97 in Singapore. Indoor W-CDMA system tests, along with comprehensive testing of equipment, are scheduled to continue until the end of the current fiscal year in March 1999. Outdoor experiments, including application tests in the Tokyo area, will be conducted from autumn 1998, with commercial development expected to begin early in 1999. The NTT DoCoMo R&D Center currently uses W-CDMA system-testing equipment from 10 domestic and overseas vendors: Ericsson (Sweden); Nokia (Finland); Lucent Technologies and Motorola (US); and NEC, Matsushita Communication Industrial, Fujitsu, Toshiba, Mitsubishi Electric and Sharp (Japan). These companies, which were selected in 1997 through public bids in line with NTT DoCoMo's procurement procedures, will not only supply equipment but will also take part in consultations on the W-CDMA system tests. The supply of testing equipment is not limited to these 10 companies; NTT DoCoMo has extended an open invitation to other manufacturers in the hopes of gaining further support for its proposed system. In addition to the W-CDMA field tests, NTT DoCoMo is also conducting research on basic mobile communications technologies and is also developing network-control software and various applications at the R&D Center. In addition, they are also working on the development of mobile personal communications terminals as well as the necessary networks and terminal equipment for its implementation. Other network systems under development include an infrastructure for IMT-2000; an Advanced Intelligent Network that will enable universal mobility and mobile multimedia; an enhanced Digital Subscriber Signaling System (DSS No. 2); and an asynchronous transfer mode (ATM) technology network infrastructure (which includes AAL type 2). The results of these research and development efforts will be included in the final version of NTT DoCoMo's W-CDMA system. The focus on fundamental technologies also includes a new fourth-generation mobile communications system. Using a broad microwave frequency band, NTT DoCoMo researchers are creating technologies for high-speed (2M- to 156M-bps) transmission for connection to B-ISDN; this would make it possible to offer such services as "mobile server worlds" and "mobile card cashing." Other development efforts include work on voice and image signal processing (such as advanced, full-motion video compression and error control), high-temperature superconductors, noise suppression, and electromagnetic compatibility (EMC).
Market potential Just what kinds of new applications can be expected from these efforts? "We have to consider where and how images combined with text and voice will be used," Tachikawa explains. "We can already see some examples in automobiles: for instance, radio communications equipment combined with a car navigation system can provide various kinds of on-demand multimedia information about traffic jams and routing, up-to-date status of resorts, restaurants, and hotels, as well as weather forecasts and Internet access." Some of these services are already provided by automobile manufacturers and electronics vendors, he continues, but "current services are limited because they rely on conventional 9.6K-bps mobile telecom systems. What we are seeking to do is make multimedia information more varied and more easily available." Regarding market potential, Tachikawa says, "We believe that the number of automobiles in Japan will hit the 100 million mark in the year 2000, while the number of mobile PCs shall reach 50 million units at the same time. If mobile telecom services are used with other services and equipment, our potential market is 150 million users. In comparision, the voice -only market is a little more than one hundred million, even if every Japanese person was using a telephone."
Standardization initiatives In Japan, the Association of Radio Industries and Businesses (ARIB) is playing a central role in standardization, by collaborating with the Ministry of Posts and Telecommunications (MPT) and the Telecommunication Technology Committee (TTC). In Europe, this role is being handled by the European Telecommunications Standard Institute's Special Mobile Group (ETSI-SMG). In late January, at a meeting held in Paris, members of the ETSI-SMG unanimously adopted a radio interface technology for IMT-2000 based on the W-CDMA method. Although it retains some elements from the TD (time division)/CDMA standards, W-CDMA as proposed by ETSI-SMG has been recognized as being identical to ARIB's proposal. This means that the coming third-generation system will be backwards-compatible with both GSM and PDC (personal digital cellular) phone systems. Regional standardization institutes - including ARIB, ETSI, and the Telecommunications Industry Association (TIA) of the US - each submitted a proposal for IMT-2000 to the ITU. That United Nations institution will then examine these individual proposals and decide on basic IMT-2000 parameters by May 1999. The ITU is expected to release completely standardized specifications by the end of the century. Kenji Maruo (maru-ken@tk.usen-net.or.jp) is a Tokyo-based journalist for high-technology and environmental issues.
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