A distributed collision resolution scheme for improving the performance in wireless LANs

The IEEE 802.11 distributed coordination function (DCF) provides a contention-based distribution channel access mechanism for stations to share the wireless medium. However, performance of the DCF drops dramatically due to high collision probability as the number of active stations becomes larger. In this paper, we propose a simple and effective collision resolution scheme for improving the performance of the DCF mechanism. Our idea is based on the estimation of the channel's contention level, by measuring duration of busy and idle periods observed on the channel at each station. In order to reduce collision probability, the proposed scheme limits the number of contending stations at the same time according to the channel contention level. Performance of the proposed scheme is investigated by numerical analysis and simulation. Our results show that the proposed scheme is very effective and improves the performance under a wide range of contention levels. (c) 2005 Elsevier B.V. All rights reserved.