A new approach to optimize bandwidth reservation for real-time video transmission with deterministic guarantees

The transmission of video requires new service models for providing quality of service (QoS). Some of these models are based on resource reservation and admission control while others rely on resource provisioning. In both approaches, optimally estimating the resource requirements of a given video is a key issue, since they are always very demanding. This paper introduces a fast and bounded method to optimize the required network resources (bandwidth) to guarantee a maximum deterministic delay for a given workload and network state. The method is based on characterizing the workload of a stored video using a reduced set of points obtained from an off-line analysis of its empirical envelope. The paper also proposes the above workload characterization to perform the admission control test using a WFQ scheduler. The evaluation of this scheme shows that it can achieve an utilization higher than a 50% for a single flow with a 1-s deadline and reach up to an 80% with a 5-s delay. Results are also compared to tests based on EDF schemes, which have been proved to be optimal with one node. It is shown that the proposed scheme is a little less efficient than the optimal EDF scheduler with one node (as expected), but it is practically as efficient (or even better with a moderately high number of nodes) than the best known RG-EDF policies with several nodes. This is an interesting result because it shows that the WFQ schedulers can achieve a similar efficiency to EDF schedulers avoiding the complexity of their admission control tests. (C) 2002 Elsevier Science Ltd. All rights reserved.