TCP Improvements for Heterogeneous Networks: The Daedalus Approach

In this paper, we present a summary of the research work done by the Daedalus group at the University of California at Berkeley to improve TCP performance in a variety of situations, including lossy wireless networks, asymmetric networks, and Web traffic workload. To improve the performance of TCP over cellular wireless networks, we have implemented a TCP-aware link layer protocol called the snoop protocol that isolates wired senders from the lossy characteristics of a wireless link. To improve TCP performance over networks exhibiting asymmetry, we have designed and evaluated techniques that reduce the adverse effects of the constrained reverse path, which TCP acks traverse. To improve TCP performance for Web-like traffic, we have designed and evaluated an enhanced data-driven loss recovery scheme that improves the performance of short transfers, as well as an integrated congestion control and loss recovery approach that improves the end-to-end performance of multiple, short TCP connections from a single host.