Efficient TCP over Networks with Wireless Links

Elan Amir, Hari Balakrishnan, Srinivasan Seshan, Randy H. Katz

TCP is a reliable transport protocol tuned to perform well in traditional networks made up of wired links with stationary hosts. Networks with wireless links and mobile hosts violate many of the assumptions made by TCP, causing degraded performance. In this paper, we describe a simple protocol that improves TCP performance by modifying network-layer software only at a basestation, without violating end-to-end TCP semantics. The main idea is to cache packets at the basestation and perform local retransmissions. Simulations of this protocol show that is it significantly more robust in the presence of multiple packet losses in a single transmission window as compared to TCP. This enables our protocol to tolerate at least 10 times as high an error rate without any performance degradation.