A simulation study of video teleconferencing traffic in ATM networks

Results of a simulation study of the potential multiplexing gains from using variable-bit-rate encoding to multiplex video teleconferencing traffic over an asynchronous transfer mode (ATM) network are presented. Simulated traffic from several video teleconferences was fed into a buffer and multiplexed onto a higher speed output line. The study observed the cell loss resulting from buffer overflow. The spacings between the start times for the individual video conferences are found to have a large role in determining the aggregate cell-loss-rate seen by the collection of calls. After the cell-loss-rate becomes non-negligible, it grows rapidly as a function of the number of input lines. The cell losses are not distributed uniformly over time but are clustered, with the consequence that the probability that a call is loss free is much better than indicated by the cell-loss-rate