Modeling the IEEE 802.11e EDCA for MAC parameter optimization

A model of the IEEE 802.11e EDCA function is presented. The model is built to be simple, but providing a clear description of the inter-relations between the EDCA MAC parameters (AIFS, CWmin, CWmax and TXOP values) and the traffic flow characteristics (packet arrival rate and packet length). The model is intended to be used as an abstraction of the IEEE 802.11e MAC protocol in WLAN flow level simulations and/or analytical studies, such as Radio Resource Management and Call Admission Control. Moreover, as the model is able to capture the reciprocal effects of tuning the MAC parameters, it can be used for optimization purposes as is presented in this paper. Thus, using a multigoal optimization function, the optimal EDCA MAC parameters are computed and evaluated in presence of elastic (BE) and rigid (V O) flows. The optimization process has the goals of maximizing the elastic throughput while assuring the bandwidth-delay requirements of the rigid flows. Finally, the outcomes allow us to define a procedure to tune iteratively the MAC parameters, showing performances close to the optimal ones.