Joint optimization of channel allocation and AP association in variable channel-width WLANs

Recently, the variable channel-width (VW) scheme was proposed to improve the performance of WLANs. Cooperative channel allocation has been studied in some existing literature under the assumption that the traffic demands of cooperative access points (APs) are constant. In fact, the traffic demands may vary when the corresponding stations change their AP association decisions. Hence, this work jointly considers the channel allocation and AP association, aims to maximize the system performance in terms of throughput and fairness. The problem is formulated as a constrained Integer Non-Linear Programming (INLP) problem, which is NP-hard. Two penalty functions are introduced to relax the constraints, and a discrete particle swarm optimization (DPSO) algorithm is then proposed to solve the problem. The simulation results show that our algorithm can improve the performance by about 20% compared to the fixed traffic scheme.