A Study of Transmission Control Protocol for Satellite Network

According to technical statistics, current TCP protocols with approximately 80% Internet applications run on perform very well on wired networks. However, due to the effects of long propagation delay, great bandwidth asymmetry, high sporadic bit error rate (BER) and etc., TCP performance degrades obviously on the satellite communication networks. To avoid the problems, TP-S, a novel transport control protocol, is introduced for satellite IP networks. Firstly, in order to increase the increment speed of Congestion Window (cwnd) at the beginning of data transmission, the traditional slow start strategy is replaced by a new strategy, known as super start. Secondly, a new packet lost discriminated scheme based on IP packets alternately sending with different priority is used in the protocol to decouple congestion decision from errors. Thirdly, bandwidth asymmetry problem is avoided by adopting modified NACK (M-NACK) in receiving ends, which is sent periodically. In addition, the sending strategy in routers is also modified along with other´s changes to support the protocol. Finally, the simulation experiments show that the new protocol can not only significantly enhance throughput performance, but also reduce sharply bandwidth used in the reverse path as compared with traditional TCP protocols and those protocols, which are recently proposed for satellite IP networks.