Improving TCP over wireless through adaptive link layer setting

Consider a communication link where the last hop is wireless and TCP is used as transport protocol over the end-to-end connection. We study the capability of the link layer to hide losses over the wireless link to TCP in spite of the time varying transmission quality. We focus on link-layer retransmission mechanisms and determine their parameter setting in such a way that a reliable communication link is provided. In particular, we choose a significant QoS metric at the transport layer and fixed its targeted value, and we adapt the maximum number of link-layer transmissions to the characteristics of the wireless link so that the desired QoS at the transport layer is provided. Results showing the impact of the link-layer retransmissions on the TCP performance are derived by using analytical models based on Markovian techniques.