tailieunhanh - Hệ thống truyền thông di động WCDMA P7

As discussed in the previous chapters, the International Mobile Telecommunications-2000 (IMT-2000) system is now an up-and-running system after its studies commenced in 1985 in pursuit of a future mobile communications system. IMT-2000 is expected to develop further into a more advanced and diversified system in response to growing demand and need. Efforts to make the IMT-2000 system more sophisticated are continuing at the International Telecommunication Union (ITU) and at various other organizations. Under the International Telecommunication Union-Telecommunication standardization sector (ITUT), a new organization called IMT-SSG (Special Study Group) has started working on the future prospects of IMT-2000 | W-CDMA Mobile Communications System. Edited by Keiji Tachikawa Copyright 2002 John Wiley Sons Ltd. ISBN 0-470-84761-1 7 Future Prospects Yoshiyuki Yasuda Takchiro Nakamura Shinji Uebayashi Hiroshi Fujiya and Tomoyuki Oya Overview As discussed in the previous chapters the International Mobile Telecommunications-2000 IMT-2000 system is now an up-and-running system after its studies commenced in 1985 in pursuit of a future mobile communications system. IMT-2000 is expected to develop further into a more advanced and diversified system in response to growing demand and need. Efforts to make the IMT-2000 system more sophisticated are continuing at the International Telecommunication Union ITU and at various other organizations. Under the International Telecommunication Union-Telecommunication standardization sector ITU-T a new organization called IMT-SSG Special Study Group has started working on the future prospects of IMT-2000. In the International Telecommunication Union-Radio communication sector ITU-R Working Party WP 8F is engaged in studies on the development and sophistication of IMT-2000 after Task Group TG 8 1 completed its tasks. The 3rd Generation Partnership Project 3GPP is working on Release 4 5 with an aim to achieve convergence with Internet Protocol IP technologies and the provision of IP multimedia services building on Release99 3GPP s first version of IMT-2000 specifications. In particular technologies geared to faster and higher-quality packet communications with IP communications in mind have been attracting a great deal of attention in a wide range of fields. Some of them are already about to undergo development for implementation with standard specifications agreed upon and frequency bands assigned such as the Time Division Duplex TDD transmission scheme suitable for asymmetric traffic. On the other hand intensive efforts are being made by organizations to improve the properties and the qualities of IMT-2000 including radio transmission .