Network-supported rate control mechanism for multicast streaming media

Layered multicasting with layered source coding enables the efficient distribution of real-time streaming media over heterogeneous networks such as the Internet. In layered multicast, rate control is required to cope with congestion quickly because packet losses in a layer with higher priority lead greater degradation of received quality. In addition, rate control for layered multicast is required to assure fair bandwidth allocation among competitive layered multicast sessions at a congested link independent of their start time. We present a novel rate control scheme for layered multicast, called Network-supported Layered Multicast (NLM). In NLM, routers distributed within the network support rate control. NLM avoids packet losses on a layer with high priority and achieves fair bandwidth allocation by filtering and signaling. A router filters a layer with low priority when it detects congestion, or when it is informed that the layer is needless by signaling. Simulation results show NLM offers significant advantages compared with receiver-driven rate control.