On 19 March 1999, the International Telecommunication Union approved key characteristics for the radio interfaces of third generation (3G) mobile systems at a meeting of Task Group 8/1 of ITU's Radiocommunication Sector (ITU-R), held in Fortaleza (Brazil). The approval marks an initial step towards the development of more detailed specifications for IMT-2000. The results of the meeting take account of input from the global wireless industry including operators, regulators, consortia and the TransAtlantic Business Dialogue.
Participants also reached consensus on additional spectrum requirements for IMT-2000 systems, providing input for consideration by the Conference Preparatory Meeting to the year 2000 World Radiocommunication Conference.
The decisions reached at Fortaleza essentially provide a way to develop a single flexible standard, with a choice of multiple access methods, that can meet the many different mobile operational environments around the world. These methods include CDMA, TDMA and a mix of CDMA/TDMA, all potentially in combination with SDMA1. Although second generation mobile systems involve both TDMA and CDMA technologies, very little use is currently being made of SDMA. The advent of adaptive antenna technology linked to systems which have been designed to optimize performance in the space dimension should enhance significantly the performance of future systems.
Participants agreed that IMT-2000 radio interfaces should include the capability of operating with both of the major third generation core networks currently under development.
IMT-2000 key characteristics are of two kinds for both the terrestrial and satellite components. One is the RF or radio frequency part (front end), where impacts are primarily on the hardware part of the mobile terminal. The other is the baseband part which is largely defined in software. In addition to RF and baseband, the satellite key characteristics also cover the architecture and the system aspects.
However, the key characteristics by themselves do not constitute an implementable specification but establish the major features and design parameters that will make it possible to develop the detailed specifications between June and November 1999.
"The participants felt that this flexible approach to IMT-2000 that provides choice among multiple access methods within a single standard will address the needs of the worldwide wireless community by allowing operators to select those radio interfaces that will best address their specific regulatory, financial, and customer needs", said Mike Callendar, Chairman of Task Group 8/1.
According to Yoshio Utsumi, ITU Secretary-General: "The work done at Fortaleza was driven by the needs of our customers for the IMT-2000 standard, namely, the global operator community and the many millions of individual users around the world who will benefit from low-cost wireless access to the information society of the twenty-first century. This new wireless standard represents an unprecedented level of global cooperation to meet the diverse needs of the different ITU regions. Besides, it offers the possibility to narrow significantly the telecommunications `gap' between developing and developed regions."
In order to make effective use of the available frequency bands, both FDD and TDD2 modes of duplexing have
to be included in the IMT-2000 global standard.
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1 CDMA: code-division multiple access; TDMA: time-division multiple access; SDMA: space-division multiple access. 2 IMT-2000 incorporates frequency division duplex (FDD), with single or multi-carrier operation, as well as time division duplex (TDD) operation. |
In this way, the new mobile standard will accommodate the different spectrum strategies which operators and countries may wish to adopt when deploying IMT-2000 systems. While some operators will use new spectrum for their IMT-2000 services, others will overlay IMT-2000 within spectrum already used to provide pre-IMT-2000 services. This will allow their customers to migrate smoothly to enhanced mobile services over a number of years, without the need to obtain additional spectrum.
Clearly, the next challenge will be to develop more detailed ITU specifications in such a way as to minimize undue technical complexities or deterioration of performance while catering to multiple operating environments.
"We have made a great step forward at Fortaleza but some very hard work still lies ahead", cautioned Mr Utsumi. "It is now time for all to take a long-term view of where everyone's interests really lie", he added. Mr Utsumi stressed that, given current forecasts on the future use of wireless systems for access to telecommunication services, IMT-2000 networks were expected not only to provide mobile communications but will also constitute a fundamental part of future telecommunication networks.
"In the light of the glittering prize that third generation systems represent, divergence of strategies in bringing 3G to the market-place is understandable. But, at the end of the day, it is the consumer that will decide on the basis of the added advantages over systems and services they already enjoy: wisdom should therefore guide us in our decisions", he concluded.
On the intellectual property rights (IPR) front, the Fortaleza meeting decided that detailed specifications should continue to be developed on the basis of the key characteristics approved by Task Group 8/1. However, a note would be incorporated, warning that CDMA schemes may be subject to IPR "blockage". This decision was reached on the basis of advice from Bob Jones, Director of ITU's Radiocommunication Bureau.
The recent announcement made by Qualcomm and Ericsson would appear to solve the IPR issue. Both companies, in their statement issued on 25 March 1999, indicated they "agreed to jointly support approval by the International Telecommunication Union [...] of a single CDMA 3G standard that encompasses three optional modes of operation [...] and to commit to ITU and to other standards bodies to license their essential patents for a single CDMA standard or any of its modes to the rest of the industry on a fair and reasonable basis free from unfair discrimination".
On the network side, Study Group 11 of ITU's Telecommunication Standardization Sector (ITU-T), chaired by Sadahiko Kano, has set up a special group of experts on IMT-2000 to provide better focus and faster results in mobile network standards. The Study Group reached this decision at a meeting in Geneva held in tandem with the Fortaleza event. The aim is to match the structures and processes established elsewhere in industry forums where all aspects of mobile system network specifications are addressed in a project-oriented manner. The creation of the group is also aimed at laying the foundation for a more consolidated structure in the years to come on a comprehensive handling of IMT-2000 and other mobility services/network aspects.
As well as being responsible for all network aspects, the group will provide a forum where ITU network and radio experts, as well as interested non-member groups of the Union can work together on IMT-2000 network-related standards. The Geneva meeting adopted an overall project plan for IMT-2000 network- related issues.
Task Group 8/1 will hold more meetings in Beijing from 31 May to 11 June 1999 and in Helsinki from 25 October to 5 November 1999. The Beijing meeting will include a joint experts meeting with ITU-T Study Group 11 network experts. This Study Group will meet again in Geneva from 22 November to 10 December 1999.
For more information, please contact: "Fabio Leite, Counsellor, IMT-2000, ITU (Tel.: +41 22 730 5940. Fax: +41
22 730 5816. E-mail: fabio.leite@itu.int )" or "Francine
Lambert, Head, Press and Public Information, ITU (Tel.: +41 22 730 5969. Fax: +41 22 730 5939. E-mail: lambert@itu.int )".
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