Enhancing TCP performance in wide-area cellular wireless networks: transport level approaches

Internet technology-based architectures and protocols for supporting multimedia traffic over wireless networks are evolving. Since TCP (Transmission Control Protocol)/IP (Internet Protocol) is the standard network protocol stack on the Internet, its use over the next-generation wireless mobile networks is a certainty. Performance of TCP would be one of the most critical issues in IP-based data networking over wireless links. This article presents a comprehensive study on the performances of the basic TCP variants (e.g., TCP Tahoe, TCP Reno, TCP New-Reno, SACK TCP, FACK TCP) in wide-area cellular wireless networks. For the basic TCP variants, an in-depth analysis of the transport-level system dynamics is presented based on computer simulations using ns-2. Impacts of variations in wireless channel error characteristics, number of concurrent TCP flows and wireless link bandwidth on the average TCP throughput and fairness performances are investigated. The maximum achievable throughput under window-based end-to-end transmission control is also evaluated and the throughput performances of TCP New-Reno, SACK TCP and FACK TCP are compared against this ideal TCP throughput performance. To this end, an overview of the major modifications to the basic TCP variants based on transport-level approaches to enhance TCP performance in wired-cum-wireless networks is presented.