Mechanisms for centralized flow rate control in 802.11-based wireless mesh networks

Cross-layer interaction between TCP and CSMA/CA-based MAC in multihop wireless networks produces suboptimal network performance, including flow rate unfairness and starvation. Rate control mechanisms can mitigate this behavior. Of particular interest are centralized mechanisms that enforce rate limits at traffic aggregation points, without modifying individual mesh routers or client devices. In this paper, we propose, design, and evaluate a framework of zero-overhead, feedback-driven centralized rate controllers. These controllers are implemented at gateway mesh routers. We use existing data traffic as capacity probes with a feedback-driven response to adapt to changes in network and traffic conditions. Using simulations and experiments on a testbed, we show an improvement in fairness by a factor of 2–3 over networks without any rate control. Further, our fairness metrics are within 2% of those achieved by a centralized controller with an omniscient knowledge of network conditions.