Exploiting the Temporal Structure of MPEG Video for the Reduction of Bandwidth Requirements

We propose a new bandwidth allocation scheme for VBR video traac in ATM networks. The scheme is tailored to MPEG-coded video sources that require stringent and deterministic quality-of-service guarantees. By exploiting the temporal structure of MPEG sources, we show that our scheme results in an eeective bandwidth which, in most cases, is less than the source peak rate. The reduction in the bandwidth requirement is achieved without sacriicing any perceived QoS. EEcient procedures are provided for the computation of the eeective bandwidth under heterogeneous MPEG sources. The eeective bandwidth strongly depends on the arrangement of the multiplexed streams which is a measure of the degree of synchronization between the GOP patterns of diierent streams. Assuming that all possible arrangements are equi-probable, we derive an expression for the asymptotic tail distribution of the eeective bandwidth. From the tail distribution, we compute several performance measures for the call blocking probability when the allocation is made based on the eeective bandwidth. In the case of homogeneous sources, we give a closed-form expression for thèbest' arrangement that results in thèoptimal' eeective bandwidth. Numerical examples based on real MPEG traces are used to demonstrate the advantages of our scheme.