Range multicast for video on demand

We explore a communication paradigm for video on demand, called Range Multicast. This schemeis a shift from the conventional thinking about multicast where every receiver must obtain the same data packet at any time. A range multicast allows new members to join at their specified time and still receive the entire video stream without consuming additional server bandwidth. Clients enjoy better service latency since they can join an existing multicast instead of waiting for the next available server stream. We also present techniques to support video-cassette-recorder-like interactivity in this environment. Unlike existing methods which require clients to cache data in a private buffer, the Range Multicast solution utilizes the shared network storage to make more efficient and cost-effective use of the caching space. Furthermore, since a range multicast can accommodate clients with different play points in the video, a client has a better chance to join an on-going multicast for normal playback after finishing a VCR operation. This strategy avoids the need for a new server stream, and thus further alleviates the server load. Our simulation results confirm the aforementioned benefits.