Eliminating Location Dependent Unfairness in WLANs

IEEE 802.11 DCF mode is a distributed channel access method for standard Wireless Local Area Networks (WLAN) with a goal of providing long-term fair channel access for the nodes. Due to the characteristics of radio signals, such as propagation attenuation and capture effect, WLAN users may experience unfair medium allocations depending on their locations. Our analysis shows that a user near the access point (AP) can access the medium several times more than a user located far away. Advanced Distributed Coordination Function (ADCF), a variant of Distributed Coordination Function (DCF) mode of IEEE 802.11, was proposed to achieve distributed weighted fair queuing. In this paper, we show that the ADCF alleviates this location dependent unfairness. Simulation results show that the ADCF mode improves the overall performance of a WLAN considerably.