Per-node throughput and fairness analysis of IEEE 802.11 wireless network with hidden nodes

Abstract

This work first seeks to develop an analytical model for the per-node throughput analysis of the IEEE 802.11 WLAN networks with hidden nodes by extending Bianchi’s model. With the analytic model we derive the per-node throughput of each node and quantify the impact of hidden nodes on per-node throughput. Through our analysis, we find that nodes having more hidden nodes are likely to have worse throughput performance than nodes having less hidden nodes, so resulting in unfairness in per-node throughput. We next propose a new algorithm, called the fake collision algorithm, to solve the unfairness due to hidden nodes. The proposed fake collision algorithm allows nodes with poor throughput to acquire more transmission opportunities by slightly modifying the Binary Exponential Backoff algorithm of the IEEE 802.11 Distributed Coordination Function. To this end, the fake collision algorithm uses a new control parameter called the fake collision probability which can be obtained from a computation algorithm that we develop based on our analytic model. We show that the fairness in per-node throughput can be achieved with the fake collision probability for each node through simulation. The current contention mechanism of the IEEE 802.11 DCF is known to have some drawbacks, e.g., collisions and low short-term fairness induced by minimized backoff stages after every successful transmission. To solve the drawbacks we propose an adaptive contention window control scheme which uses a single backoff stage while maintaining the advantages of the current IEEE 802.11 DCF such as simplicity and distributivity. We first introduce the key concept called the optimal collision probability and explain the detailed procedure of the proposed scheme which is based on the optimal collision probability. The convergence of the proposed scheme is shown. The validation from simulation results shows that the proposed scheme provides higher throughputs and higher short-term fairness than the IEEE 802.11 DCF.