UMAV: a simple enhancement to the IEEE 802.11 DCF

We propose a simple enhancement to the Distributed Coordination Function (DCF) of the IEEE 802.11 MAC protocol, called the Unified Multiple Access with Variable contention window (UMAV), to improve the throughput performance of the 802.11 DCF systems. The basic ideas of UMAV are that (1) a new P(polling)-mode is introduced for frame transmissions in addition to the conventional C(contention)-mode used in the DCF, so as to reduce the number of contending stations; and (2) an enhanced uniform backoff scheme is used to replace the binary exponential backoff scheme of the DCF, so as to achieve a low frame collision probability and maximize the channel utilization. Our in-depth simulation shows that UMAV outperforms the IEEE 802.11 DCF significantly in terms of both the aggregate system throughput and the average station access delay under various load conditions. Moreover, UMAV can react properly and quickly to the traffic load fluctuations, and achieve excellent fairness, a desirable by-product.