Throughput performance of transport-layer protocols over wireless LANs

Considers the performance of transport-layer protocols over networks where one of the links is wireless. A reliable transport protocol is responsible for end-to-end data integrity, and will retransmit lost or errored data. Compared to a link over copper or fiber, a wireless link will have a much higher error rate. Link-layer retransmissions can reduce the error rate on the radio link, but the interaction of link-layer retransmission with end-to-end retransmission can be complicated. The authors have investigated, via analytic, numerical and simulation techniques, the end-to-end effects of link-layer retransmissions in the presence of a reliable end-to-end transport protocol. The results identify the mechanisms affecting end-to-end performance when retransmissions are used to get better error performance on a link. They quantify the increased load on the link due to competing retransmission strategies, and, for a transport protocol modeled on TCP, they identify the region of loss rates where link-layer retransmissions have the undesirable effects of both reducing end-to-end throughput and increasing link utilization in the network segment where bandwidth is the most expensive