On VBR Video Teleconferencing over ATM Networks

This paper examines the problem of video transport over ATM networks using knowledge of both video system design and broadband networks. We find that the following trends hold for all sequences examined. First, increasing the delay in the video system decreases the necessary peak rate and significantly increases the number of calls that can be carried by the network. Second, as an operational traffic descriptor for video, the leaky-bucket algorithm appears to be superior to the sliding-window algorithm. And finally, with a delay in the video system, the statistical multiplexing gain from VBR over CBR video is upper bounded by roughly a factor of three, and to obtain a gain of 1.5 to 2.0 can require the operational traffic descriptor to have a window or bucket size on the order of a thousand cells. We briefly discuss how increasing the complexity of the video system may enable the size of the bucket or window to be reduced.