Evaluation of Coexisting Enhanced TCP Flows on the High-speed Internetworking Satellite (WINDS)

The Wideband InterNetworking engineering test and Demonstration Satellite (WINDS) has an ultra-high speed international Internet-based communication system. However, the characteristics (for example, transmission bit errors, large propagation delay) of its satellite communication markedly degrade the throughput of conventional TCP (TCP Reno). Therefore, the satellite communications should adopt an enhanced TCP which has been proposed for high-bandwidth and long-delay networks, and can utilize the resource of the satellite network at a maximum level. In this study, we have compared the performance of ten TCPs (TCP Reno and nine enhanced TCPs) by building an experimental environment of the satellite communication over WINDS. The measurement results have shown that TCP Hybla achieves the best performance among all TCPs in terms of the throughput of communication over WINDS. Therefore, TCP Hybla could be the best solution to communications established on WIND’s satellite network. However, the congestion control of one TCP Hybla flow has not only suppressed the transmission speed of other flows of TCP Reno, but also prevented the windows size of other TCP Hybla flows from reaching the stable state when multiple TCP flows coexist on the same satellite link. This should be taken into account when using TCP Hybla.