Vegas-W: An Enhanced TCP-Vegas for Wireless Ad Hoc Networks

The performance of TCP-Vegas is not satisfactory in multihop ad hoc networks over IEEE 802.11 MAC protocol. We analyze the problem with a unified network model and simulation results. We observe that the aggregate throughput of all traffics decreases as the load of the network increases. The main reasons lie in Vegas's large minimum congestion window, large reset slow start threshold and aggressive window increase policy. To fix these problems, we propose a modified TCP protocol based on TCP-Vegas for multihop ad hoc networks, called Vegas- W. We extend the congestion window to fraction; change the probing mechanisms of legacy TCP-Vegas in both slow start and congestion avoidance and update slow start threshold tracking the stable window. We evaluate the performance of Vegas-W through ns-2. Extensive simulation results under a variety of scenarios show that Vegas-W can improve the throughput up to 87% over legacy TCP-Vegas and up to 27% over FeW, which is another improved algorithm based on TCP-Newreno scenarios.

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