Jeff,
Thank you for your efforts to give us the reports the last couple of days. Here is some view form the Chinese side toward IMT-2000 meeting.
cn-telecom.com
Evolution from GEDGE and GSM-CDMA to IMT-2000
TG8/1 task force of the 8th research panel on the ITU-R is committed to advancing its evaluation and integration of IMT-2000 radio transmission technology (RTT). By the end of September 1998, as many as 16 RTT proposals inclusive of MSS (mobile satellite system) had been submitted. These proposals were generally made by RTT evaluation panelists of IMT-2000, including URTA W-CDMA and DECT by ETSI of Europe, CDMA-2000, UWC-136, WIMS W-CDMA and W-CDMA/NA From TIA and T1P1 of the US, W-CDMA from ARIB of Japan, TC-SCDMA from CATT of China, Global CDMA I(synchronous) and Global CDMA II(asynchronous) from TTA of South Korea, SAT-CDMA from LEO satellite systems, SW-CDMA (satellite wide band) and SW-CTDMA (CDMA/TDMA-hybrid wide band satellite system) from ESA, ICO RTT from International Communication Organization, Horizons from INMARSAT, and INX from Iridium LLC. Out of the 16 proposals mentioned above, the first, ten are IMT-2000 ground system, while the rest 6 proposals indicate the determination of RTT to include MSS into MT-2000.
This article does not intend to cover satellite system. The topic will center on evolution and integration of IMT-2000. We will first discuss technological evolution paths-EDCE and GSM-CDMA, which are based on backward compatibility. Then we will analyze and elaborate on integration and evolution strategy of IMT-2000. Finally, suggestions will be made on China scenario.
1. Technological evolution of EDGE and GSM-CDMA
GSM has dominant market share worldwide. It is forecasted that by 2000, GSM will have 62% of the digital mobile communication market. While evolving towards IMT-2000 from 2-G, the issue of how to create strong backward comparability upon GSM market potentials and its advantages of basic-layer net-work will influence designers, manufacturers and operators of both 2-G TDMA and 2-G CDMA One. They were forced to develop corresponding solution-EDCE (and GEDGE in broad sense) and GSM-CDMA, two most important and typical evolution paths came into being against the background.
1. EDGE
EDGE (Enhanced Data Rates for GSM Evolution) was first proposed by ETSI as a new technology to evolve from GSM towards IMT-2000, short-termed as GSM 384. Adopting O-16QMA for modulation, it increases GSM transmission rate to 384kbit/s. In January 1998, UWCC (Universal Wireless Communication Consortium), based on TDMA-D-AMPS market, selected 8-PSK in its UWC-136HS solution for the purpose to integrate with EDGE. In May 199, ETSI decided to switch to 8-PSK for EDGE modulation for its evolution path towards IMT-2000, resulting in GEDGE (Global EDGE), the combination of GSM and UWC-136. It is expected that by 2000, nine out of ten digital mobile subscribes will select either GSM or D-AMPS. By then, EDGE will be used as an effective means for high-speed data communication in GSM and D-AMPS network. Recently, Ericsson successfully demonstrated EDGE?s data-processing capability at 384kbit/s for wireless multi-media services such as INTERNET/INTRANET, email and videoconference in GSM network. The main weakness of EDGE is its dependence on smooth evolution based on market demand for network and service and its inconsistency with W-CDMA in terms of air interface. Therefore, some countries may skip EDGE and directly phase into MT-2000.
2. GSM-CDMA
GSM-CDMA was proposed by Qualcomm, the poineer of N-band CDMA. Based on cdmaOne, it allows GSM-MAP to airinterface with CDMA, integrating GSM and cdmaOne and moving forward to IMT-2000. Those GSM operators planning to adopt GSM-CDMA can pile CDMA base stations on their existing GSM network. Those CDMA base stations can work at GSM frequency band or any other frequency band such as 800MHz, 1800MHz, 1900MHz, PCS/PCN or even 3-G UMTS frequency band. These CDMA base stations can be managed by one or multiple BSC and directly connected to existing GSM MSC through GSM A interface.
Dual-mode handset will search GSM-CDMA. In case of GSM-CDMA network found, it works at GSM-CDMA air interface. As a full-function GSM terminal, the handset supports global roaming and has all those common features. Its SIM card can work both in GSM terminal or GSM-CDMA terminal.
Up to date, GSM-CDMA has passed preliminary tests. Vodafone and Qualcomm have jointly set up a trial network. A new model commercial CDMA handset with GSM software and SIM card has been rolled out. Demonstration of Voice and GSM service has been given. Other experiments including one in Asia are expected to take place in the second half of 1999 before GSM-CDMA terminals and infrastructures are put into commercial use. The standardization work of GSM-CDMA is also in progress to achieve international recognition for infrastructures purchase by operators and to broaden availability of handest and infrastructure suppliers. The make or break of GSM-CDMA mainly relies on cost and price of dual-mode handset, the possibility to achieve investment advantages during the network migration process and market deployment speed.
In a word, GEDGE and GSM-CDMA may become important technological path in the transition from 2-GTDMA to IMT-2000.
II. Integration and evolution of IMT-2000
The so-called integration has not reached consensus. Most commonly, it refers to more coordination and consistency of RTT basic parameters and network parameters for cost-effective manufacturing, global roaming, even effective and flexble utilization of wireless requency resource.
Despite not a single operator, manufacturer and end-user oppose to integration, a complete integration of the above-mentioned ten RTT proposals is still far away as it involves conficts of political and market interests among different regionas as well as IPR issues. Therefore, evolution towards 3-G mobile communication can only be implemented in a phased way based on regional development.
From technical perspective, the above-mentioned GEDGE based on TDMA does not exclude GSM-CDMA. Using more complex modulation and circuitry self-adaptive technology, it could be the successful prelude for IMT-2000 based on GSM/D-AMPS around year 2000.
Many similarities can be found among the ten RTT proposals. Better integration in some sense is entirely possible. However, the final results of the efforts and driving forces to a great extent depends on the fight of interests among different countries, regions, consortiums and enterprises.
1. UTRA W-CDMA put up by unified Europe
Under the strong coordination of ETSI, Europe proposals were first merged into five concepts, namely and finally into ETS/UTRAW-CDMA (FDD and TDD). Thus FDD and TDD reach consistency in terms of major parameters such as chip rate, frame length, time slots/frame, modulation method and wave shaping requirements. Moreover, supplementary network applications are possible, all driven by united interests of the European Group.
2. Integration of TIA TR46.1 WIMSW-CDMA and TIPI W-CDMA/NA in the U.S.
The integration is crystallization of the joint efforts of WIMS (Wireless Multimedia and Messaging Services) and W-CDMA/NA (based on North American GSM Alliance) during the evolution towards IMT-2000. The integration leads to uniformity in terms of 4 major areas, namely, chip rate at 4.096Mchip/s, frame length at 10ms, self-adaptive multi-rate vocoder and asynchronous base station.
3. Efforts to integrate with GSM, 2-G mobile communication with widest market
The key problem lies in the integration of UTRA W-CDMA-C(DS) backed by GSM market and TIA TR45.5 backed by cdma One Market.
At present, RTRA W-CDMA-C (DS) has not only the widest GSM market, but also many RTT partners such as : W-CDMA from ARIB of Japan, WIMS W-CDMA from TIA and W-CDMA/NA from T1P1 of the U.S., Global CDMA II from TTA of South Korea. In contrast, cdma 2000-(MC) from TIA CDG, baqsed on cdma One (N-band CDMA IS-95) IPRs, supports smooth evolution with basic chip rate at 3.6864 Mchip/s. Though with fewer proposal partners, cdma 2000-(MC) is still exerting strong influence on W-CDMA-(DS) through cdma IPRs. Technologically, main obstacles that hinder the integration of W-CDMA (DS) with cdma 2000-(MC) are as follows:
1. Chip rate: 4.096 MChip/s (1.024*4)* N vs 3.684 MChip/s (1.2288*3)*N;
2. BTS voice channel pilot code: achieve synchronization of base station network thgough ATM instead of GSP
3.downlink voice channel pilot code: adpting continuous coding for pilot code which shares time division with service code
4.frame length: short at 10 ms and 5ms, long at 20ms
5.frequency planning at 2GHz: IMT-2000 core frequency band proposed by ITU applied to PCS and others.
The most difficult part of integration stems from the technical side, involving conflict of political and economic interests of various regions, countries, operators and manufacturers in their considerations of backward compatibility. W-CDMA-C(DS) camp has supporters of Ericsson, Nokia and other global GSM operators, while cdma 2000-(MC) side has Qualcomm, Lucent and other global cdma Once operators. Ericsson, Qualcomm and major operators will paly a critical role in the fight including IPR.
4. Frequency planning
As for problems with regard to frequency planning at 2GHz, 1850-1990MHz which lies within the core frequency band of 1885-2025GHz/2110-2200MHz for IMT-2000 has been allocated for PCS service by North America. Those PCS operators who adopt cdma One system advocate that the path towards IMT-2000 should be evolution within the band via cdma 2000-(MC). The Europeans support ITU-as-signed 2 GHz band to become the core for IMT-2000. It seems that no material compromise can be reaches. Fully aware of such difficulty, ITU is seeking extended bandwidth while taking consideration of potential bandwidth demand for multimedia transmission so as to achieve better RTT integration and global roaming. Possible candidates for stand-by extended fruquency band (for global and regional applications) are : 470-806MHz, 806-960MHz, 1429-1501MHz, 1710-1885MHz, 2025-2110MHz, 2200-2290MHz, 2290-2300MHz, 2300-2900MHz and 2900-3400MHz. WG7B oppose to the using of 2025-2110MHz and 2200-2290MHz for IMT-2000 as they have already been used for space scientific research. The issue of 2290-2300MHz and 2300-2400MHz being stand-by extended requency band remains in dispute as it may conflict with the existing iperations in various countries.
III. Strategic Considerations and Recommendation for China
The following considerations and suggestions for China?s scenario are based on the above analysis and discussion on the evolution and integration of IMT-2000.
1. A universal IMT-2000 is beneficial to operators, manufacturers and end-users. Therefore China should always encourage and promote any efforts and progress for the integration of major types including unified planning of core and extended frequency band of IMT-2000.
2. The likelihood is the two major RTT technological solutions, namely W-CDMA and cdma 2000(MC), instead of reaching complete integration, will only achieve integration in certain aspect to the maximum extent. Only based on this ?family concept? can global roaming and seamless coverage be acquired in the best possible way. Consequently, specific strategies for the basic market and business shall be considered practically, carefully and positively for China?s IMT-2000.
3. While TDD is flexible in dealing with data service, asymmetric data service in particular, FDD excels in symmetric data services including voice, B-band multi-media service, IDSN and cellular service and is often regarded as a mainstream technology. Therefore, in promoting China?s TD-SCDMA, solid R&D activities, international cooperation and efforts on making it a global standard shall be deployed simultaneously. Meanwhile, China should gather more influence upon and deepen its involvement in the R&D of FDD B-band CDMA. As a result, China can benefit from the supplementary development of FDD and TDD during the transit towards IMT-2000 and the subsequent business growth.
4. China?s operators shouls positively generate the development strategy towards IMT-2000, for instace, further development strategy for cdma One in China, including the integration of cdma One and GSM MAP through GSM-CDMA and subsequent evolution towards IMT-2000; and how to fully utilize the world?s largest GSM network in China to effectively develop China?s IMT-2000 business. Those network operators should also make an in-depth study on the integration solutions, timely put forward alternatives and make corresponding decisions on B-band CDMA.
5. In such an era of knowledge economy with customer and market as the main driving forces, it is important to properly deal with the dialectical relations between market and technology driving forces. While developing China?s R&D strategy for IMT-2000 system equipment, multidirectional efforts should be deployed to develop backward compatible technologies. Correspondingly, operators should support and encourage the high-tech national industry while making its development plan based on forward and backward compatibility.
6. The great market potential of China can be used as a leverage at the negotiation table with international manufacturers, operators and investors in forming strategic partnership. With regard to IPR (including Know-how), reciprocal partnership in bilateral and multi-lateral cooperation shall be encouraged and the formation of basic principles and stipulation beneficial to global standardization progress shall be promoted.
7. Organized activities should be carried out to predict market demand and to finalize the standards for IMT-2000. Those activities may in clude spectrum demand forecast for IMT-2000 service in 5, 10 and 20 years, research on network architecture, air interface, protocal specs, system properties and technical equipment for FDD, TDD and MSS. A 3-G mobile communication system suitable to China shall be selected base on the demand of operators, production of R & D institutions and potentials of the industrial development. Study should also be made on frequency spectrum demand, frequency allocation bandwidth required, protection bandwidth and Electro-magnetic compatibility of FDD, TDD and MSS. In consideration of the core frequency band and stand-by extended frequency for extension proposed by ITU for IMT-2000, China should study on the possible interference with the existing microwave, radio positioning and broadcasting services and find out relevant solution. Close attention shall be paid to the latest development of ITU?99 CPM conference and WRC conference in 2000 to facilitate spectrum planning for IMT-2000 including effective frequency allocation.
Brian H. |
