TCP Performance Evaluation over GEO and LEO Satellite Links between Performance Enhancement Proxies

Transmission Control Protocol (TCP) is the most widely used protocol for end-to-end data transmissions over inter-networks. However, the congestion control algorithm of TCP was not created to match the special characteristics of satellite links, resulting in a drastically performance degradation. The employment of TCP split connections coupled with link level retransmissions and satellite link tailored TCP versions has been proven effective in hiding corruption losses from TCP to improve end-to-end performance. Using NS-2 simulations, this paper evaluates and compares popularly used TCP versions such as New Reno, Hybla, Vegas, DVegas and Westwood+ over GEO VSAT- and LEO-based satellite links employing performance enhancement proxy (PEP) based on snoop. Simulation results show that with the use of snoop proxy, TCP Hybla outperforms the rest of TCP versions, improving the usage of satellite links that are affected by losses not due to congestion. The second good candidate is DVegas over satellite PEP. When the Explicit Control Protocol (XCP) is employed as TCP PEPs, it would improve TCP performance to get high transfer rates and respond to congestion in a correct and scalable way.