Rate Adaptation Mechanism for Multimedia Multicasting in Wireless Networks

Nowadays, wireless networks have been deploying everywhere, with IEEE 802.11 as the most popular standard. However, wireless resources are scarce and wireless condition varies often. These limitations are crucial for applications with tight QoS requirements such as video or voice over IP. To cope with the problems, the standard has provided many features including multi-rate capability, which is the focus of this paper. Multi-rate capability is beneficial especially for multicast transmission, in which the traffic sent by default at basic rate may result in capacity wasting because of longer channel occupancy. Moreover the lack of feedback mechanism makes it difficult to deal with reliability or service quality. Some protocols have proposed to use rate adaptation to handle the problems but none of them takes into account quality of experience (QoE), which is an essential quality indicator in multimedia traffic, for making decision. Therefore, we propose in this paper a novel rate-adaptation mechanism based on quality of experience. We make use of PSQA (Pseudo-Subjective Quality Assessment) tool for obtaining mean opinion score in real-time. Our objective is to improve bandwidth utilization while satisfying user experience. We illustrate significant performance improvement obtained by our scheme according to this goal.