Satellite Network Transmission Control Mechanism Studies

Satellite communication has become an important part of the Internet because of its unique advantages. The use of satellites for Internet access is a trend in the development of satellite communications. TCP is the most widely popular transport layer protocol which provides end to end reliable data transmission. However, due to the characteristics of satellite channels, TCP protocol is not well adapted satellite networks which has a great success in cabel networks. Therefore, how to improve TCP performance on satellite channels in the application has become an import research topic.This paper analysis the reason that TCP protocol performance in the satellite networks not as well as the cabel networks. The main contributions of this dissertation are summarized as follows:(1) Because of the different causes of packets loss in cable networks and satellite networks, and its impact for the TCP performance, this paper proposed satellite network transmission control protocol TCP-SaSnoop on the base of Snoop protocol. TCP-SaSnoop algorithm transport packets which loss in the satellite networks.(2) Due to the characteristics of the bandwidth-limited in the satellite network, this paper proposed the rate-based control of satellite networks transmission control mechanism: RC-SaSnoop, on the base of the TCP-SaSnoop algorithm. RC-SaSnoop algorithm is no longer immediately forward the received data packets, but adjust the transmission rate according to the satellite networks real utilization.(3) By analyzing the shortcomings of the RC-SaSnoop, this paper proposed transmission control mechanism RC-SaSnoop/ERED based on the active queue management. Monitor the number of packets through the gateway station, forecast and control the early congestion. RC-SaSnoop/ERED algorithm can prevent network congestion and improve satellite network bandwidth utilization. At the same time, reduce the numbers of time out. This can improve the performance of TCP better.Simulation and experimental results show that when the satellite networks have congestion, error and bandwidth-limited channels, the improved algorithm can effectively improve TCP's perfomance in goodput, file transfer time and fairness.