Performance Evaluation of the Deadline Credit Scheduling Algorithm for Soft-Real-Time Applications in Distributed Video-on-Demand Systems

Abstract

In this work we investigate a promising scheduling algorithm referred to as the Deadline Credit (DC) algorithm, which exploits the available bandwidth and buffer space in communication networks to serve a diverse class of prerecorded video applications. We provide simulation results when the DC algorithm is applied to a hierarchical architecture distributed VoD network, which fits the existing tree topology used in today's cable TV systems. The issues investigated via the simulations are: the system utilization, the influence of the buffer space on the delivered QoS, and the fairness of the scheduling mechanism. We examine cases with homogenous and diverse video streams. We also contribute a modification to the DC algorithm so that in cases when the video applications have different displaying periods, the video streams obtain a fair share of the network's resources. Finally, we validate our results by simulating actual videos encoded in MPEG-4 and H.263 formats.