TCP and SCPS over Space Networks

Space network are now become a very important and necessary complementary to the ground networks, it will extend the terrestrial Internet networks to space. However, there are still many challenges exist before the space-ground integrated networks come true, and how to transport data reliably in space networks is the very difficult one among these challenges. TCP has been a robust and efficient transport layer protocol for terrestrial networks, but it does not fare very well in the space environment because of the long-link delay, high bit-error-rate, etc, compare with the terrestrial networks. However, it does provide an excellent base for extension. One of the attempts to improve transport layer performance in space networks has been the development of SCPS-TP, which is a popular modification of TCP that is very efficient for space environments. In this paper we compare the performance of TCP and our implementation of SCPS-TP SNACK (Selective Negative Acknowledgement) over paths with different BER and different delays. Our goal is to determine the improvement in throughput and link utilization when the SCPS-TP SNACK instead of standardized TCP mechanisms are used. The results show that SCPS-TP has a better performance than the regular TCP in space communication.