CWFC: A contention window fuzzy controller for QoS support on IEEE 802.11e EDCA

Recent literature shows the limitations of the IEEE 802.11e protocol when handling real-time industrial traffic. This paper proposes an approach to overcome some of these limitations and improve the QoS support for real-time traffic, with only minor changes to the IEEE standard. The proposed approach tries to reduce the number of collisions, so that the available bandwidth is used more efficiently by the real-time data traffic, especially in high traffic conditions. This is achieved through a dynamic adaptation of the back-off parameters CWmin and CWmax for the different access categories. Such an adaptive control is performed by a fuzzy-logic controller, that takes into account both the throughput and frame retransmission count.