Traffic descriptors for 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. The following issues are addressed: video system delay caused by internal buffering, traffic descriptors (TD) for video, and call admission. We find that while different video sequences require different TD parameters, 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 four, and to obtain a gain of about 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. >