1A REACTIVE BROADCASTING PROTOCOL FOR VIDEO ON DEMAND

Broadcasting can reduce the cost of video on demand services by distributing in a more efficient fashion videos that are simultaneously watched by many viewers. Rather than waiting for individual requests, broadcasting schedules repeated broadcasts of the various segments of a video ahead of time. Hence it performs best when it is used to distribute videos that are watched concurrently by hundreds or thousands of viewers. We propose a reactive broadcasting protocol that addresses the problem of distributing moderately popular videos in a more efficient fashion. Like all efficient broadcasting pro-tocols, reactive broadcasting assumes that the customer set-top box has enough local storage to store at least one half of each video being watched. Unlike other broadcasting protocols, reactive broadcasting only broadcasts the later portions of each video. The ini-tial segment of each video is distributed on demand using a stream tapping protocol. Our simulations show that reactive broadcasting outperforms both conventional broadcasting protocols and pure stream tapping for a wide range of video request rates