Providing unrestricted VCR functions in multicast video-on-demand servers

Full support for interactive VCR functions can be achieved only by dedicating a channel for each customer. Unfortunately, channel dedication should not be used in a multicast video-on-demand (VoD) system, because it degrades scalability; and hence economical viability, which is usually achieved by multicasting videos. The authors, therefore, propose and evaluate a fully-interactive, yet scalable, on-demand service in multicast VoD systems. In the proposed framework, support for interactive operations is provided by (1) allocating a fraction of the VoD-server's channel capacity to handle interactive operations which would otherwise be blocked, and (2) using partial caching of programs in customers' premise equipment (CPE) to merge customers back in synchronization with broadcast channels. Their evaluation results indicate that batching policies under the proposed framework can make an attractive tradeoff between scalability and customers' QoS.