Distributed Channel-Adaptive Fair Allocation for IEEE 802.11e WLAN

Distributed Channel-Adaptive Fair Allocation (DCAFA) is proposed to extend the IEEE 802.11e Enhanced Distributed Coordination Function (EDCF), by halving the contention window (CW) after ζ consecutive successful transmissions to reduce the collision probability when channel is busy. The scheme computes an adaptive threshold function for each priority queue by taking into account the channel load. Simulation results show that DCAFA outperforms EDCF in-terms of global throughput, throughput of traffic class, frame discard probability and average delay in medium and high load cases. They also show that the proposed analytical model is accurate and achieves a high degree of fairness among applications of same priority level.