Threshold-Based Rate Control for Multimedia Transport over Markovian Wireless Channels

In this paper, we examine source rate control (SRC) via multiple buffer thresholds over a Markovian wireless channel. In the SRC scheme, a multimedia source reduces its packet rate (thus degrading the encoding quality) gradually whenever the queue length exceeds certain thresholds. When the queue length drops below a specific threshold, the respective preset source rate is restored. The performance of this scheme is analyzed by defining a loss function of a source in the queueing system, which consists of packet dropping at the end of queue, the throughput degradation and the quality degradation by a source encoder. This function is evaluated by modeling the system as a level dependent M/G/l queue. Numerical examples are presented, which show that the loss function and average packet delay are minimized at an optimal rate reduction factor.