On Rate Adaptation for Video Multicast with Layered Coding over Multirate Wireless Networks

Video multicast over multirate wireless networks imposes great challenges in designing efficient rate adaptation schemes due to the multi-layer hierarchical video coding and heterogeneous fading across multicast receivers. We propose a cross-layer framework for rate selection in video multicast, where different video layers have diverse loss-rate QoS requirements and thus may employ different transmission rates varying with the channel state information (CSI). Specifically, we first propose an orthogonal frequency-division multiple access (OFDMA) - code division multiple access (CDMA) based scheme to avoid feedback collisions while efficiently identifying CSI from all multicast receivers. Second, we develop a queue management strategy such that the transmissions for different video layers can be synchronized. Third, we design the rate adaptation scheme to control receivers' loss rates at each video layer not to exceed the thresholds specified by upper protocol layers. Also conducted are simulation results to show the effectiveness of our designed rate-adaptation scheme.