The Design And Implementation Of TCP/SCPS Gateway

With the development of society and advancement of technology, in order to meet the daily needs of national defense, China’s space technology has been developed. For all to see, some famous projects such as China’s Shenzhou series of carrier rockets, BeiDou satellite navigation system, Chang’E moon projects, have achieved gratifying results and have laid a solid foundation for the space-based information networks.As a link between aerospace systems, the space communication system plays an irreplaceable role. Compared with terrestrial communication, the space wireless environment is much worse and communication distance is much longer, which cause some problems, such as high delay, high error rate, and severe asymmetry link. So the efficiency decline sharply when terrestrial communication protocol is applied directly to space communications link. In1999, the CCSDS (Consultative Committee for Space Data Systems) released a series of blue books, including SCPS-NP, SCPS-TP, SCPS-SP and SCPS-FP, which provides a series of robust space communication protocols. The SCPS-TP was updated to the second edition in October2006. Also in the transport layer, SCPS-TP is more adaptable than TCP in space communications. Based on the spatial characteristics of the communication channel, improvements and optimization have been made in advanced congestion control algorithm, window negotiation algorithm, header compression and other aspectsIn this paper, the inelasticity of traditional TCP in space communication is expounded through the analysis of the characters of long delay, high BER, high forward/return link asymmetry of space communication and TCP working in the space communication system. Base on the improvement of SCPS, the implementation of TCP/SCPS gateway is analyzed and designed. And a demo gateway connecting the SCPS network and TCP/IP network is built to prove the feasibility and efficiency of TCP/SCPS gateway.