Integration between satellite and terrestrial networks is to play a very important role in the creation of a Global Internet which supports user mobility. Unfortunately, in these scenarios, TCP protocol tends to perform poorly because of high delay-bandwidth product, high bit error rate (BER) and burst errors mainly due to shadowing. The use of a reliable data link protocol, well suited to mobile geostationary satellite channel characteristics, can improve TCP performance appreciably. However, introducing a more variable end-to-end delay causes, as a side effect, a new problem: the competition between retransmission mechanisms at transport layer and data link layer. In order to solve this problem a TCP Performance Enhancing Proxy has been defined and validated. The simulation results, in terms of web-page download mean time, have shown that a local approach results in substantial improvements in HTTP performance, solving the retransmission competition problem.
