Research On Satellite Adaptive Reliable Multicast Protocol Based On Rateless Codes

As people's demand for high-rate multimedia services continues to increase,limited bandwidth resources has become a major bottleneck in the development of wireless communication.Satellite communication network has a natural multicast feature to provide data transmission services for group users with the same demand,which greatly improves the efficiency and the utilization of network resources.Meanwhile it is becoming popular in the development of the wireless communication.However,satellite communication network and land network are quite different.Serious rain attenuation and long Round-Trip Time impose high requirements on the transmission quality and transmission efficiency.Therefore,this paper focuses on the multicast error control mechanism and adaptive transmission technology in satellite multicast system,and designs an adaptive multicast transmission protocol based on rateless code.Then,two adaptive algorithms for satellite multicast are proposed,which have important significance for improving the spectrum efficiency of satellite reliable multicast system.Firstly,this paper introduces the theory of rateless code and reliable multicast.Secondly,for the characteristics of Long RTT,complex channel changes,and difficult intra-group communications,we present a reliable and adaptive transmission protocol for the satellite multicast system,which is designed from the aspects of transmission frame format,transmission flow,retransmission method,and feedback method,and it can effectively avoid the feedback implosion.Thirdly,according to the proposed protocol,we design an adaptive algorithm based on transmission phase and extreme value theory prediction,and the other algorithm based on user grouping and order statistics estimation.Finally,for the problem that the first adaptive algorithm has a large number of retransmissions,the corresponding optimization scheme is analyzed and designed.The two algorithms proposed in this paper are suitable for both static and dynamic changes of satellite channels.Compared with the existing reliable multicast algorithms,they have higher transmission efficiency.Under the condition that the distribution of multicast users changes with time,the two algorithms have good adaptive tracking feature and high spectral efficiency.