Enhancement of HSWA-TCP Congestion Avoidance Scheme for High Speed Satellite Communication Network

The Transmission Control Protocol (TCP) is the mostly used protocol for data transmission over terrestrialwire line networks. However, TCP‟s congestion control algorithm wasn‟t created to match the special characteristics (long delay and high Bit Error Rate) of satellite links, resulting in a drastically performance degradation. For high speed satellite communication networks to match its characteristics such as long delay and high Bit Error Rate several protocols are designed. SCPS-TP is one of the protocols designed for satellite networks but its throughput is low in high speed satellite environment. SCPS-TP congestion avoidance algorithm is modified to adapt the characteristics of high speed satellite communication network which is called the HSWA-TCP. HSWA-TCP is simulated and results show that performance of HSWA-TCP decays very sharply in high BER. To overcome these limitations Enhanced HSWA-TCP protocol is developed which depends not only on RTT and BER but also on bandwidth estimation. Enhanced HSWA-TCP continuously estimate bandwidth utilized by the sender, and based on that adjusts the cwnd rather than just at the time of packet loss. Simulation results show that, Enhanced HSWA-TCP throughput is improved and remain constant even in high BER and on average, throughput of Enhanced HSWA-TCP is 56% improved compare to HSWA-TCP.