Queue Size Distribution of an ATM Switch with VBR Video Traffic

Abstract

Many analytical tools have been devised to analyze CBR video coders, however only few have been applied to the VBR case. In this paper, we present a semi-Markov process model for approximating the stochastic equilibrium queue length distribution for VBR video sources multiplexed onto a constant capacity ATM channel. The sources are assumed to have two rates, and generate cells that pass through pre-buffers before joining a common queue on a FIFO basis. The model is based on a state process defined by the average rate of change of the queue length as a function of the number of active mini-sources of each type, and is solved using matrix-geometric techniques. An Access Control mechanism uses these results inside its policing function to control access to the network at call setup. Numerical results are obtained for various conditions, and compared to the ones obtained from simulation and fluid-flow models, and good agreement was achieved.