Call admission control of teleconference VBR video traffic in ATM networks

We study the call admission control problem for an ATM multiplexer loaded with heterogeneous low-motion VBR video sources. To estimate the bandwidth required by a VBR video source, we characterize its traffic by five parameters: peak rate, bottom rate, mean rate, standard deviation, and the coefficient of the autocorrelation function. The aggregate traffic of a number of VBR video sources is modelled by a discrete-time Markov modulated deterministic process (D-MMDP) which can be obtained by the superposition of a number of identical and independent two-active-state mini-sources. Based on the effective bandwidth approach and the Gaussian approximation, we derive simple formulas for estimating the required bandwidth. From the numerical results, we conclude that the stationary Gaussian approximation produces a very efficient and yet conservative call admission control scheme for the teleconference VBR video sources studied. The performance of the effective bandwidth approach degrades due to its inability of making full use of statistical multiplexing gain when the number of source increases.