Resource control for the EDCA mechanism in multi-rate IEEE 802.11e networks

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 congestion. We discuss the application of the framework for achieving class-based 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 these application scenarios we discuss how to estimate the optimum minimum contention window and the congestion prices based on the 802.11e parameters and actual measurements, in order to achieve efficient channel utilization