Hierarchical video-on-demand system for ATM networks

Video-on-Demand (VOD) is expected to be the key residential service in the near future. A VOD system consists of three components: the VOD server, the transport network, and the end user. In this paper, we focus on the design of the network module of a VOD system. We propose a hierarchical VOD network structure which can be used to achieve a low cost, high performance, high scalability, and high reliability VOD system. In this hierarchical VOD system, the level-2 gateway is the most important element. All video streams retrieved from storage systems are pumped by the level-2 gateway to clients. In this paper, three mechanisms are proposed for pumping video streams with throughput, jitter, and delay guarantees. First, due to the large variety of traffic characteristics of Motion Pictures Expert Group-1 (MPEG-1) video streams, we propose to transmit an MPEG-1 video using the Piecewise Constant Rate Transmission and Transport (PCRTT) technique. Second, to guarantee throughput, and to avoid jitter, and delay, a new traffic control algorithm, referred to as the Modified Generic Cell Rate Algorithm (MGCRA), is proposed. Finally, the call admission function is implemented based on PCRTT rates and dynamic Virtual Path (VP) bandwidth allocation. The proposed architecture and mechanisms have been implemented and are shown to be a practical and efficient solution for large scale VOD systems.