Comparison of distributed fair QoS mechanisms in wireless LANs

It is well known that the distributed coordination function (DCF) of the IEEE 802.11 MAC protocol is not suitable for supporting multimedia and QoS-sensitive applications because of its inherent lack of QoS support and fairness. Recently, several distributed QoS mechanisms have been proposed which translate user QoS requirements into typically a single parameter of the DCF protocol. In this paper, we compare the pros and cons of the major distributed QoS mechanisms, and propose a new mechanism that provides superior performance and supports two different QoS models. The proposed mechanism is based on deficit round robin scheduling and translates the user throughput requirements into the 802.11 MAC interframe space and backoff interval parameters. We show via simulations that the proposed mechanism provides low variability of throughput and delay and has the advantage of low complexity.