Research On The TCP For Micro-satellite Flying In Formation

Satellite communication has the advantage that covering a wide range, easy to access andremote communications, satellites flying in formation not only has the characteristics ofsatellite communications, but also plays the advantage of each satellite in a network, so thatthe system can achieve better performance. The TCP protocol is the most widely applied inInternet. But the TCP protocol based on the wired network cannot be well applied to the poorsatellite communication link. Therefore, how to improve the performance of the TCP protocolin satellite communications has become a hot topic.In this paper, we summarize several improvement schemes, according to characteristicsof satellite communications, a simple and effective scheme which is called N-TCP has beengiven.First of all, the paper describes technology of satellites flying in formation. According tothe satellite orbit parameters, we design a simple FLOWER formation network. Describes theimplementation of the TCP protocol and the congestion control mechanisms of TCP.According to the characteristics of satellite link, We point out the problem of TCP protocol insatellite communication and propose specific improvement direction. We assume that thepackage losses are caused by network congestion in wired network. But in the satellite link,the reason of package losses may be the poor link. According to the number of overstockmessage, we can distinguish the reason of packet losses, the number of overstock can becalculated by RTT in the link. thereby take different congestion control scheme to make thecongestion window to maintain large for a long time, so that we ensure the system’sthroughput,and improve the performance of the system.And then introduce the usage of the OMNeT++and how to implement the TCP protocolin OMNeT++, and build a simulation model of satellites flying in formation.Finally, we simulate and analysis the congestion window and throughput of the N-TCPand compare the performance of N-TCP with the TCPReno, TCPTahoe algorithm, It verifiesthat the N-TCP can significantly improve the TCP algorithm.