Resource Control for the Enhanced Distributed Channel Access (EDCA) Mechanism in IEEE 802.11e

We investigate the problem of efficient resource control for elastic traffic in IEEE 802.11e’s Enhanced Distributed Channel Access (EDCA) mechanism. Our approach considers an economic modelling framework based on congestion pricing that captures how various factors, such as the probability of attempting to transmit a frame, the use of the basic CSMA/CA or the RTS/CTS procedure, and the physical layer transmission rate, contribute to the congestion in an IEEE 802.11e network using the EDCA mechanism. We discuss the application of the framework for achieving class-based proportional throughput differentiation, for performing explicit congestion notification (ECN) marking based on the level of congestion in the wireless channel, and for modelling the performance of TCP congestion control over EDCA. In the aforementioned application scenarios we discuss how to estimate the optimal minimum contention window and the congestion prices based on the 802.11e parameters and actual measurements, in order to efficiently utilize the wireless channel. Experiments demonstrate the application of the proposed framework, compare simulation and analytical results, and identify the gains in using the optimal minimum contention window.