Performance study of MAC for service differentiation in IEEE 802.11

In a wireless local area network (WLAN), medium access control (MAC) layer access parameters are usually differentiated for various classes of users to provide different quality of service (QoS). In particular, in this paper, we investigate the MAC layer performance of IEEE 802.11e based WLAN, where the traffic flows are classified and each class is assigned different MAC parameters, such as inter-frame space (IFS), and contention window (CW) size. These parameters play a critical role in determining the system performance. Thus, an appropriate mathematical model is desired to determine the QoS differentiation on these parameters and guide the system design. However, so far, little work was reported. We propose a novel model based on the Markov chain, which takes into account almost all the important MAC parameters, CW, IFS, class number, etc. Despite its simplicity, it is demonstrated that our proposed model agrees quite well with the results obtained with the time-consuming simulations.