TCP Over WiMAX: A Measurement Study

This paper present active measurement results from a commercial IEEE 802.16/WiMAX-based network, with primary focus on TCP performance. This paper compare four TCP variants, namely New Reno, Cubic, Vegas and Veno, using throughput, Round-Trip Time (RTT), and retransmission rate metrics. While all TCP variants achieve similar throughput, they do so in different ways, with different impacts on the network performance. It identifies adverse effects of TCP window auto-tuning in this environment and demonstrates that congestion losses dominate random wireless errors on the physical link. This paper reveals several issues for this WiMAX-based network, including limited bandwidth for TCP, high RTT and jitter, and unfairness during bidirectional transfers.