Rate Adaptation Mechanisms for Multimedia Multicasting in Wireless IEEE 802.11 Networks

The rising number of wireless users and terminals has pushed the deployment of many applications over wireless networks. Video multicasting is one of them. Wireless multicast has a great benefit in terms of resource utilization. Due to wireless nature of the media, a packet that is sent only once can reach all recipients. However, multicasting lacks in feed back mechanism. This makes it hard to deal with reliability or quality of service. Moreover, in order to reach all nodes especially the farther ones, multicast is always sent at the basic rate of 1 or 2 Mbps. This low rate may penalize other traffics and waste bandwidth capacity because of longer channel occupancy. As IEEE 802.11 standard provides possibility of multi-rate transmission, we propose to adapt multicast transmission rate according to quality of experience perceived at multicast users. We illustrate the significant performance improvement obtained with our scheme comparing to other existing schemes.