Supporting multimedia traffic in 802.11e WLANs

We study the performance of WLANs with infrastructure, when the IEEE 802.11e EDCA function is employed. We focus on VoIP, video and TCP data traffic, and run experiments with ns-2 to assess the performance of different classifications of the traffic flows. Our aim is to investigate the capacity of a WLAN system in terms of number of traffic connections that can be supported, given the QoS requirements of voice and video flows. We show that, using a proper set of access parameters, we can obtain acceptable performances for VoIP while maintaining a good video playout quality, which has been estimated by means of realistic visual comparisons. As for video traffic, we propose a technique to exploit the synergies between application layer (H.264 codec) and MAC layer, and show that this approach can significantly improve the system performance.