Adaptive Contention Window Scheme for WLANs

Elwathig Elhag and Mohamed Othman

Faculty of Computer and Information Technology, University Putra Malaysia, Malaysia

Abstract: In this paper, a new bakeoff algorithm is proposed to enhance the performance of the IEEE 802.11 Distributed Coordination Function (DCF) which employs Binary Exponential Backoff (BEB) algorithm. We present simulation results showing that the new algorithm outperforms the BEB algorithm and compared with the previously proposed enhancement algorithms, a salient feature of our algorithm is that it performs well when the number of active stations is large and small : that is, in both heavy and light contention cases. Furthermore, the adaptive window adjustment algorithm is simpler than previously proposed enhancement schemes in that no live measurement of the WLANs traffic activity is needed and don't assume constant packet sizes.

Keywords: IEEE 802.11, wireless local area networks, WLANs, DCF, binary exponential backoff, ACW.

Received February 2, 2006; accepted April 30, 2006