Cross-Layer Optimization of the Link-Layer based on the Detected TCP Flavor

Abstract—Numerous flavors of TCP are already in existence, and further variations on TCP mechanisms are frequently being introduced in order to, for example, cope with the packet loss characteristics of wireless links. Moreover, the proliferation new wireless standards and the relative performance differences among them have been mushrooming in recent years. Given the increasingly heterogeneous nature of the Internet, mechanisms do not usually exist for a server to specifically select an appropriate TCP flavor for each individual download. In this paper, we therefore present and assess a cross-layer solution for a node (e.g. a base-station) to rapidly adapt lower layer characteristics (the coding rate and local ARQ retransmissions threshold) based on the detected TCP flavor, in order to optimize the end-to-end performance of the download for that utilized flavor of TCP. We demonstrate that the proposed scheme has considerable potential to improve the overall download throughput, while placing no burden on the server and requiring no changes to existing TCP flavors. I