Transporting compressed video over ATM networks with explicit rate feedback control

We propose a scheme for transmission of variable-bit-rate compressed video over ATM networks using the explicit-rate congestion control mechanisms proposed for the available bit rate (ABR) service. Compressed video is inherently bursty with rate fluctuations over both short and long time scales. We feel that this source behavior can naturally take advantage of the ABR service, since the ABR explicit-rate schemes allow sources to request varying amounts of bandwidth over time, while reserving a minimum for the entire duration of the connection. Moreover when the bandwidth demand cannot be met, the network provides feedback indicating the bandwidth currently available to a connection. This information can be used to match the video source rate to the available bandwidth by modifying the quantization level used during compression. We use trace driven simulations to examine how effective the enhanced explicit rate scheme is in "rate matching" between the network and the source and the effect on end-end delay. We also look at the sensitivity of the proposed scheme to the estimates of the network round-trip times and to inaccuracies in the rate requests made by sources.