Link-Layer Error Recovery Techniques to improve TCP Performance over Wireless Links

Recent technology has involved TCP in wireless applications even if it was originally designed to work over wired links. It is well known that wireless links are usually characterized by phenomena like shadowing, multipath propagation and path loss that cause an increase in the bit error rate. Moreover,TCP protocol was supposed to interpret all the losses as due to congestion because of it was designed to work over wired networks. All these problems caused by the wireless application of TCP usually degrade TCP performances. In order to improve TCP behavior over wireless links several solutions have been proposed in literature as: the split connection approach, the end-to-end approach and the link-layer approach. Starting from the link-layer solution that have been studied by Barman and Matta, the main contribution of this thesis is the study of the effects of different modulation formats on the maximum achievable value of an objective function, defined as the ratio between the TCP throughput and a cost function. Appropriate power management and error correction techniques are assumed to improve the link reliability observed by TCP and increase the objective function performance accordingly