Design of multicast delivery for providing VCR functionality in interactive video-on-demand systems

Multicast delivery is one of the solutions to reduce the cost in a large video-on-demand (VoD) system. However, multicast transmission makes much more difficult the implementation of interactive functions for individual users and introduces start-up delays for the users, which contradicts the idea of on-demand services. In this paper, we first try to explore and evaluate the performance of different multicast VoD systems. A new scheme called single-rate multicast double-rate unicast (SRMDRU) is then developed to minimize the system resources for supporting full VCR functionality in a multicast VoD system. This scheme also allows multicast systems to support true VoD services so customers can be served as soon as the system receives the requests. Computer simulations show that the multicast systems using the SRMDRU scheme perform much better than other multicast systems in terms of system blocking probabilities.