| As a supplement and extension of the ground network, the broadband satellite network is an important component of air space ground integrated network system in the future. However, the communication bandwidth of the satellite is limited, how to improve the channel utilization and satisfy user quality of service is the key problem of multiple access and bandwidth allocation strategy in limited resources. Therefore, the research on broadband satellite network access control technology is an important research topic in broadband satellite networks. For broadband geostationary earth orbit(GEO) satellite networks, high transmission delay makes in protecting satellite channel utilization at the same time, decrease the end- to- end delay become the focus of the broadband GEO satelite network access control study.In this thesis, the existing multiple access and bandwidth allocation strategy is systematic studied. Based on the broadband satellite networks, according to the bandwidth allocation on demands, a kind of improved multiple access protocol called CFDAMA-RPA is presented. And the scheme is also improved, in order to reduce the end to end delay and enhance the utilization of channel. The main work of this thesis is as follows:(1) Among all of the Combined Free/Demand Assignment Multiple Access(CFDAMA) protocol with different terminal request strategies, each scheme has its different advantages and disadvantages. The scheme which employs Round Robin assignment of request slots(CFDAMA-RR), can offer improved delay/utilization performance of a satellite channel but polling the round robin cycle was relatively long. The primary disadvantage with the CFDAMA-RA scheme is loss of request packets as a result of channel contention, and the main limitation in the performance of the CFDAMA-PB strategy is channel domination by transmitting terminals, inhibiting other terminals from receiving free assigned slots and making requests. The thesis incorporates all the request strategies described above, with their strengths and weaknesses complemented, can offer improved delay/utilization performance of a satellite channel.(2) In the process of combined all the request strategies with random access, round robin access and piggy backing access, for the on-off nature of traffic model, in order to enable the terminals which is grouping backlog and in the OFF period can access signal channel resource reservation as soon as possible, the proposed algorithm arranged the terminals which in the OFF period use random reservation and recorded the assignment order. Due to the existence of random reservation collision, after a collision in the need of back off retransmission in order to avoid occurring the secondary collision, satellite arranged the ground terminals that first occurrence of collision with round robin reservation in order to access channel as soon as possible. Also in the process of arranging the off period terminals use round robin reservation, the arrangement scheme were optimized with the static assignment changed to dynamic allocation, thereby reducing the collision probability and enhance the performance of the algorithm. |
