Adaptive Contention Window Adjustment for 802.11-Based Mesh Networks

Wireless mesh network (WMN) is a new type access network bearing large numbers of various traffic flows. Reliable data flow and real-time multimedia flow are the two primary categories of traffics. Most real-time multimedia flows have QoS requirements for throughput, average delay and jitter. In order to ensure these QoS requirements, an adaptive contention window adjustment scheme (ACWA) is proposed for IEEE 802.11-based WMN, which adjusts channel access probability via changing the initial upper bound of contention window. Cross-layer design is adopted in ACWA. MAC layer cooperates with network layer to implement the differential priority channel allocation by adjusting contention window dynamically. Channel state, queue state and flow priority requirements are considered. Evaluations show that ACWA can provide assurance on bandwidth and average delay requirements for flows and partially reduce local congestion in 802.11-based mesh networks.