Investigation of TCP performance over wireless internet

Abstract

The demand for providing Internet services over wireless links has grown rapidly in recent years. Although TCP (Transmission Control Protocol) has been performing well over the traditional wired networks where packet losses occur mostly because of congestion, it cannot react efficiently in wireless networks, which suffer from significant non-congestion-related losses due to reasons such as bit errors and handoffs. The main reason for this poor performance of TCP is the fact that it cannot distinguish between packet losses due to wireless errors from those due to congestion. It responds to all losses by invoking congestion control and avoidance algorithms. Moreover, TCP sender cannot keep the size of its congestion window at optimum level and always has to retransmit packets after waiting for timeout, which significantly degrades end-to-end delay performance of TCP. This issue has attracted significant research interests and many schemes have been proposed to address the issue. This project will investigate the performance of a few representative mechanisms, which will improve both throughput and delay performance of TCP in wireless environment significantly. That is, Snoop protocol, Explicit Loss Notification (ELN), Explicit Congestion Notification (ECN).