An approach to enhance the QoS support to real-time traffic on IEEE 802.11e networks

This paper proposes an approach to overcome some limitations of the 802.11e protocol highlighted in recent literature and improve the QoS support provided to realtime industrial traffic. The proposed solution does not change the IEEE 802.11e protocol, but introduces a technique to reduce the number of collisions and therefore to use the channel more efficiently for real-time traffic, especially when the traffic load is high and approaches saturation conditions. The proposed mechanism, called a Contention Window Adapter, dynamically changes the contention window size of the different Access Categories defined by the IEEE 802.11e protocol according to the wokload conditions of the wireless network. The paper describes the rationale behind the CWA mechanism, the algorithm itself and discusses the performance obtained through simulations run using ns-2.