1、C:DOCUMENTS AND SETTINGSQGV33745MY DOCUMENTSDOWNLOADSR-QUE-SG04.233-1995-MSW-E.DOC 17.10.03 15.07.10 QUESTION ITU-R 233/4 Dedicated user digital satellite communications systems and their associated architectures (1995) The ITU Radiocommunication Assembly, considering a) that dedicated/user-oriented
2、 networks external to the ISDN using capacity of international, regional and national satellite systems are being established; b) that there are various alternative architectures and corresponding reference digital paths and user requirements for these networks; c) that more information and criteria
3、 on technical and operational matters associated with such systems would be useful in the development of economical satellite systems; d) that these networks may include the use of very small aperture terminals (VSAT) in the earth segment, which may be dedicated to a single user; e) that new fixed-s
4、atellite service networks involving a large number of low-Earth orbit satellite and the associated earth stations are being developed, and that these networks also involve multiple intersatellite links; f) that digital satellite links will continue to form part of evolving digital networks carrying
5、a variety of services including those of the ISDN; g) that Question ITU-R 78/4 exists to investigate the integration of satellites into the B-ISDN; h) that it would be desirable to establish various network architectures for digital satellite links to provide designers of equipment and systems with
6、guidance for their implementation; j) that these network architectures may help designers in allocating impairment for digital transmission links, decides that the following Question should be studied 1 What network architectures are conceivable and preferable to facilitate the design and constructi
7、on of dedicated user systems for digital transmission? 2 What network architectures are preferable from overall cost efficiency, taking 1 into account? 3 What are the preferred user requirements for performance and availability on the satellite link? 4 What are the factors which characterize alterna
8、tive network topologies, system architectures and link control protocols? 5 What is the impact of the network requirements on the characteristics of the earth stations? 6 What are the standardized dedicated user/network digital interfaces to be recommended? - 2 - 4/1-E C:DOCUMENTS AND SETTINGSQGV33745MY DOCUMENTSDOWNLOADSR-QUE-SG04.233-1995-MSW-E.DOC 17.10.03 15.07.10 further decides 1 that the results of these studies should lead to the formulation of an appropriate Recommendation by 2006. _
