Dual-metric hybrid protocol for application level multicast for live video streaming

This paper proposes a Hybrid Protocol for Application Level Multicast with Dual Metric (HPAM-D) for live video streaming. HPAM-D constructs data distribution trees based on two performance metrics, namely, latency to source and loss rate experienced by the clients. The protocol is evaluated against the latency based single-metric HPAM and a modified HPAM-L which aims only to optimize loss rate regardless of the latency to source. HPAM-L acts as a control experiment in the evaluation. Another novel feature introduced in HPAM-D is the detection of likely local congestion via a heuristic based on the computation of a client´s relative loss rate with respect to the data received by its parent as opposed to the commonly used absolute loss rate experienced by a client. Simulation results show that HPAM-D not only helps a client to reduce unnecessary parent switches thereby reducing protocol overheads but also maintains a low loss rate for its clients without compromising the RDP performance compared to the latency based, single-metric HPAM.