Energy efficient contention window adaptation algorithm for IEEE 802.11 WLAN

This paper introduces a new contention window (CW) adaptation algorithm to reduce the collision level in an IEEE802.11 based network with the main objective of maximizing energy efficiency while maintaining required Quality of Service (QoS) performance. The main concept of the proposed algorithm is to dynamically adjust the contention window size according to the network load condition, which represents the level of congestion in a network. Performance analysis is carried out using an OPNET based simulation model to study the effects of CW adaptation on the energy efficiency and QoS performance. Performance of the proposed algorithm is compared with the legacy Distributed Coordination Function (DCF) and other CW adaptation algorithms such as Fast Collision Resolution (FCR) and CW tuning. The results show that the proposed algorithm outperforms the other techniques in terms of reducing collision level and that directly translates to higher energy efficiency as well as better QoS performance. The proposed protocol can be extended to support multi-class traffic with different priorities.