Improving TCP Performance over Wireless WANs Using TCP/IP-Friendly Link Layer

In this paper we propose the use of a TCP/IP-friendly link level error recovery mechanism with novel design in conjunction with state-of-the-art Transmission Control Protocol (TCP) enhancements to improve TCP performance on network paths involving Wireless Wide-Area Network (W-WAN) links. We show that by combining a selected set of TCP enhancements TCP performance is significantly improved over W-WAN links. In addition, we employ a TCP/IP-friendly link layer protocol which minimizes the additional delay due to the Automatic Repeat reQuests (ARQ) by limiting the number of retransmission attempts and by adding redundancy in the retransmitted frames in a novel way. We perform experiments in an emulated satellite environment with a real implementation of the TCP/IP-friendly link layer and TCP enhancements in Linux. The results show that both TCP enhancements and link-level ARQ significantly improve TCP performance over W-WAN links, and combining the approaches yields the best performance.