Activity Probability-Based Performance Analysis and Contention Control for IEEE 802.11 WLANs

In this paper, we develop a contention window (CW) control scheme for practical IEEE 802.11 wireless local area networks (WLANs) that have node heterogeneity in terms of the traffic load, transmission rate, and packet size. We introduce activity probability, i.e., the probability that a node contends for medium access opportunities at a given time. We then newly develop a performance analysis model that enables analytic estimation on the contention status including the collision probability, collision time, back-off time, and throughput with comprehensive consideration of node heterogeneity. Based on the newly developed model, we derive the theoretically ideal contention status, and develop a CW control scheme that achieves the ideal contention status in an average sense. We perform extensive NS-3 simulations and real testbed experiments for evaluation of both the proposed performance analysis model and CW control scheme. The results show that the proposed model provides accurate prediction on the contention status, and the proposed CW control scheme achieves considerable throughput improvement compared to the existing schemes which do not comprehensively consider node heterogeneity.