Broadband Geostationary Orbit Satellite Systems, Access Control Methods

This thesis investigates the techniques and issues associated with Medium Access Control Modes for geostationary satellite systems. Satellite capacity is a limited commodity that must be used aas efficiently as possible to support a large number of subscribers and generate high returns for the service provider.In the GEO satellite communication system based on TDMA, there are three primary strategies for assigning capacity to multiple users: Fixed Assignment, Random Access and Demand Assignment. In TDMA satellite system, these designed to provide significant improvementsin the delay performance of Geo-stationary Earth Orbit (GEO) satellite channelssupporting a finite number of ground stations with bursty data traffic. There are a number of variants of CFDAMA ,differing in their provision and strategy for making DAMA requests. So it introduce the CFDAMA-RR and CFDAMA-PR. The BTDAMA include BTDAMA-PD and BTDAMA-FD, there are the frame formats and request and scheduling strategies.The OPNET software was employed in the computer simulation. The OPNET models of the two modes were presented in the dissertation. The performances between CFDAMA-PR with Round Robin request , CFDAMA-RR, BTDAMA-PD and BTDAMA-FD chemes were compared by computer simulation. Smulation resulation results demonstrate that compared to CFDAMA-RR scheme , CFDAMA-PR with Round Robin rquest can offer improved delay/throughput of the satellite channel. A one time, at low channel loads, the CFDAMA reachesthe better delay/throughput performances. Due to it can effedtive use the leaving slots. Under high load conditions, BTDAMA provides very low mean end_to_end delay due to the separation of the request and scheduling funcyions. Lastly, the performance of BTDAMA-UG which is simulated by computer indicates that the high group of terminals gets low end-to-end delay at cost of low priority group of terminals.