Supplying Instantaneous Video-on-Demand Services Using Controlled Multicast

In this paper, we propose and evaluate the performance of a multicast technique, called controlled CIWP, for supplying video-on-demand services. Similar to batching schemes, controlled CIWP allows two clients that request the same video to share a channel. Unlike batching, the controlled CIWP scheme does not delay the earlier request in order to promote sharing. Instead, sharing is ensured by permitting the client with the later arrival time to join an ongoing multicast session started for the earlier request. However, controlled CIWP does not let a client join an ongoing multicast session whenever possible. A threshold is used to control the frequency at which new multicast sessions are started. We derive the optimal threshold that minimizes the number of server channels required. Our simulation study shows that the controlled CIWP significantly improves the performance of the VOD service.