Satellite communications strategy selection for optimal LEO satellite communication

[摘要] ENGLISH ABSTRACT: A low earth orbit satellite system can be useful in numerous communication applicationswhere physical connections are not possible. Communication time available from any point onearth to the satellite is less than one hour per day. This one hour is fragmented into smallertime slots due to the satellite orbiting. This is not much time to transfer data and there iseven less time available to transfer data when there are other external factors affecting thesystem. It is thus crucial to optimise the satellite communications link so that more data canbe transferred per orbit.The goal of this thesis is to improve the performance of a low earth orbit satellite communicationchannel by varying certain parameters of the system, such as the protocol used,modulation scheme, packet size, transmission power etc. and then to observe how theseparameters influence the system. The protocols that were chosen to be implemented areCSMA-CA, CSMA-CA with DSSS technology and Round-Robin Polling.A simulator for each protocol was designed with the Opnet platform, so that specific parameterscould be changed and the results observed, in order to optimise the communications linkbetween the satellite and ground stations.The results showed that there is no particular configuration of modulation scheme, packetsize, transmission power etc. presenting the best overall solution for LEO satellite communications.It must be considered what the specific LEO satellite application would be used for andthe characteristics required by that specific application. A suitable configuration must subsequentlybe chosen from the set of configurations available to satisfy most of the applicationrequirements.

[发布机构] Stellenbosch University