1、QUESTION ITU-R 84-4/4*, *Use of non-geostationary-satellite orbits in mobile-satellite services (1988-1990-1992-1993-2007) The ITU Radiocommunication Assembly, considering a) that various types of non-geostationary-satellite orbits can provide global coverage within latitudes between the 90 parallel
2、s utilizing configurations suitable for a variety of satellite communication applications; b) that studies should continue to be carried out in the ITU-R to establish guidelines for sharing within the mobile-satellite service (MSS), and between MSS and other services; c) that use of orbits other tha
3、n geostationary for some mobile-satellite applications could provide better coverage for areas above certain latitudes and in general provide improved services because of shorter path links and also facilitate joint use with other services, e.g., the radiodetermination services; d) that elevation an
4、gles to the geostationary orbit are very low from higher latitudes which accentuates the communication problems caused by multipath and shadowing effects. The use of orbits other than geostationary may improve this situation; e) that such systems operating in different frequency bands may have disti
5、nctly different characteristics, decides that the following Question should be studied 1 What types of non-geostationary-satellite orbits are suitable for providing mobile-satellite services? 2 What are the technical and operational advantages and limitations of those non-geostationary-satellite orb
6、its, and the systems utilizing them? 3 Subsequently to the studies in accordance with decides 1 to 3, what technical specifications should be provided to meet the objective of considering c)? further decides 1 that the results of the above studies should be included in (a) Recommendation(s); 2 that the above studies should be completed by 2007. Category: S2 _ *This Question should be brought to the attention of Radiocommunication Study Groups 4, 7 and 9. *Former Question ITU-R 84-4/8.
