Smoothing, statistical multiplexing, and call admission control for stored video

Variable bit-rate (VBR) compressed video is known to exhibit significant, multiple-time-scale rate variability. A number of researchers have considered transmitting stored video from a server to a client using smoothing algorithms to reduce this rate variability. These algorithms exploit client buffering capabilities and determine a "smooth" rate transmission schedule, while ensuring that a client buffer neither overflows nor underflows. In this paper, we investigate how video smoothing impacts the statistical multiplexing gains available with such traffic, and we show that a significant amount of statistical multiplexing gains can still be achieved. We then examine the implication of these results on network resource management and call admission control when transmitting smoothed stored video using VBR service with statistical quality-of-service (QoS) guarantees. Specifically, we present a uniform call admission control scheme based on a Chernoff bound method that uses a simple, novel traffic model requiring only a few parameters. This scheme provides an easy and flexible mechanism for supporting multiple VBR service classes with different QoS requirements. We evaluate the efficacy of the call admission control scheme over a set of MPEG-1 coded video traces.