Enhancing congestion control with adaptive per-node airtime allocation for wireless sensor networks

Wireless sensor networks are usually equipped with single radio interfaces where a sensor node can participate in only one transmission at a time. As a result, a node´s airtime is ¿shared¿ by multiple flows that pass through the node. Although it is practically important, how to effectively allocate airtime among flows has not received sufficient research attention in the existing literature. In this paper, after showing the potential gain from adaptive airtime allocation in alleviating network congestions, we formulate a new congestion control problem using network utility maximization with respect to airtime fractions, transmission power and flow rate. We prove that the new congestion control is a concave problem and develop a local algorithm for adaptively tuning airtime fractions in parallel with power and rate. Simulation results show the convergence of the optimal airtime allocation as well as its effectiveness in boosting flow rate and conserving power.