1、 1 - Place des Nations Telephone +41 22 730 51 11 Telex 421 000 uit ch E-mail: itumailitu.int CH-1211 Geneva 20 Telefax Gr3: +41 22 733 72 56 Telegram ITU GENEVE www.itu.int Switzerland Gr4: +41 22 730 65 00 QUESTION ITU-R 46-3/4 Preferred multiple-access characteristics in the fixed-satellite serv
2、ice (1990-1993-2007) The ITU Radiocommunication Assembly, considering a) that satellites in the fixed-satellite service (FSS) are simultaneously used by many earth stations at different locations; b) that various multiple-access methods including time division multiple-access (TDMA) and code divisio
3、n multiple-access (CDMA) are already used or planned by various administrations; c) that multicarrier-based multiple-access schemes such as orthogonal frequency division multiplexing frequency division multiple-access (OFDM-FDMA or OFDMA), multicarrier CDMA (MC-CDMA) and multifrequency TDMA (MF-TDMA
4、) have been adopted or are being considered to be adopted in many terrestrial system standards for future implementation; d) that, in order to ensure the efficient use of frequency spectrum and orbits, it may be desirable to determine the optimum multiple-access characteristics; e) that recommendati
5、on of certain system characteristics may be desirable; f) that the transmission characteristics of multiple-access systems, especially multicarrier- based multiple-access systems, may be of importance in their interaction with one another; g) that increases in interference on CDMA signals can be acc
6、ommodated by reducing system capacity, decides that the following Question should be studied 1 What are the preferred multiple-access methods taking into account in particular the nature of the network, the modulation methods and the different system characteristics used in the FSS? 2 What character
7、istics of multiple-access systems might usefully be recommended as preferred and, if appropriate, what operational characteristics should be selected for their application? 3 What is the effect of interference on networks using CDMA techniques? 4 What is the effect of other transmission parameters such as coding and modulation on the systems or networks using multicarrier-based multiple-access techniques? - 2 - further decides 1 that the results of these studies should lead to the formulation of appropriate Recommendations by 2010. Category: S2
