No abstract

No abstract

No abstract

In this paper, we report on the performance of a (single-node) multiplexer when its input consists of variable bit rate (VBR) coded video sources so as to develop a better understanding of the issues involved in transporting VBR video services over ATM networks. Two different cases of cell distribution over a frame period have been considered: (i) random arrival with uniform distribution (also approximated by Poisson arrival process), and (ii) burst arrival. In each case, the cell-loss and buffer occupancy characteristics are studied as a function of frame synchronization across the sequences, buffer size, and utilization. Through experiments, we show that (i) the network utilization is maximized when sources are uncorrelated and their cells are uniformly distributed, (ii) the buffer O C C U P~~C Y gravitates toward either the empty side or the full side, and (iii) when the distribution of cells is smoothed on a per frame basis, the frame synchronization across sequences has little impact on the cell-loss characteristics; however. when the cells are transmitted in a burst at frame intervals, a strong dependence on the frame synchronization across different video sources is found. It is concluded that to improve performance, the cell transmission from each source should be smoothed at least over a frame period, which will also remove any constraint on the synchronization of the frames across the video sequences sharing the same nod+) and/or link(s).

Market growth for PC multimedia and digital video owes largely to the rapid adoption of IS0 compression standards by the industry. For VDT services, the MPEG-2 set of standards have clearly emerged as the preferred coding method for VDT networks. For point-to-point switched video or multimedia connections, ATM has emerged as the technology of choice for switching and transport. Sudhir Dixit and Paul SkellySUDHIR DIXIT i s responsihle for urchitecting broadband video dial tone networks at " E X Science and Technology.PAUL SKELLYis a memher of technical sfaffat GTE Laboratories. Inc.