A Combined Frequency Assignment and AP Scheduling for Throughput Maximization in IEEE 802.11 WLAN

Abstract

Frequency channels are allocated to the access-points (APs) satisfying the co-channel interference in an IEEE 802.11 WLAN. Very few APs can be activated simultaneously with a conflict-free frequency assignment to them, due to limited number of frequencies. This may lead to a reduced aggregate throughput. We argue that aggregate throughput can significantly be improved by allowing some of the selected interfering APs to be activated with the same frequency but to operate in a fairly time-scheduled manner to satisfy the co-channel interference. We introduce the notion of class and cluster and based on it propose a combined frequency assignment, AP scheduling and association algorithm with the objective of maximizing the aggregate throughput. Simulation results show that the proposed algorithm is superior than both the algorithms that ignores the co-channel interference altogether by assuming proper frequency planning and that allows to activate only those APs for which a conflict-free frequency assignment exists.