Multimedia Networking, TCP, Multicast, Congestion Control

We investigate the applicability of an equation-based approach to estimating TCP-compatible data rate for layered multicast sessions with very slowly varying send-ing rates and develop mechanisms to improve layer subscription decisions at the receiver. A layered multicast session consists of a sender emitting data to a num-ber of cumulative layers and a set of receivers subscribed to a subset of the layers. Receivers estimate the loss fraction, the round-trip time, and use a TCP-model to estimate a TCP-compatible data rate. A receiver uses the computed rate for layer join and leave decisions. We conducted a series of testbed and simulation experi-ments under a variety of conditions to investigate the TCP-Friendly Rate Control (TFRC) behavior in a scenario with constant bit rate sender. We show that the computed loss event rate and the calculated rate depend on the sending rate com-pared to the normal equation following TFRC. We modied the loss estimation algorithm and show that using true packet loss as congestion measure cancels the dependency and gives accurate estimates of congestion. We also discuss possible subscription level management strategies using the sending rate independent es