A dynamic rate control mechanism for integrated networks

Abstract

To achieve better statistical gain for voice and video traffic and to relieve congestion in integrated networks, a dynamic rate control mechanism is proposed. This mechanism, using a variable rate coder, adjusts the source coding rate based on network feedback information. An analytical model is developed to evaluate the performance of the mechanism for voice traffic. The feedback delay for the source node to obtain the network congestion information is presented in the model. Significant improvement in statistical gain can be realized for smaller capacity links (e.g., links that can accommodate less than 24 calls) with a reasonable feedback time (about 100 ms); but this increase causes a temporary degradation in voice quality to a lower rate. The authors show that whether the feedback delay is exponentially distributed or constant does not significantly affect performance in terms of fractional packet loss and average received coding rate. Using the number of calls in talkspurt or the packet queue length as measures of congestion provides comparable performance.