An improved 802.11 DCF in a hybrid environment
ICUFN'09 Proceedings of the first international conference on Ubiquitous and future networks
IEEE/ACM Transactions on Networking (TON)
A Control Theoretic Approach for Throughput Optimization in IEEE 802.11e EDCA WLANs
Mobile Networks and Applications
Analysis of a prioritized contention model for multimedia wireless sensor networks
ACM Transactions on Sensor Networks (TOSN)
Kalman Filtering: Estimate of the numbers of active queues in an 802.11e EDCA WLAN
Computer Communications
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A number of works have tried to adjust the contention window in order to provide differentiated quality of service in IEEE 802.11-based wireless networks. By giving different service classes different CWs, the distribution of backoff intervals (chosen randomly, on the interval [O, CW]) will reflect the desired service classes. However, these protocols cannot deliver firm service guarantees while maintaining high network utilization, particularly under congested network conditions. In this article we propose a new MAC protocol featuring a sliding CW (SCW) for each network flow. The SCW dynamically adjusts to changing network conditions, but remains within a per-class predefined range in order to maintain a separation between different service classes. Each flow's SCW reacts based on the degree to which class-defined QoS metrics are satisfied. Simulation results show that compared to the enhanced distributed coordination function (EDCF) scheme of 802.11e, SCW consistently excels, in terms of network utilization, strict service separation, and service-level fairness.