Client buffering techniques for scalable video broadcasting over broadband networks with low user delay

In traditional near-VOD (NVOD), the number of streams required is high if the user delay goal is low (say, 2 minutes). In this paper, we study the use of client buffering to reduce such bandwidth requirement. We first study a scheme based on streaming approach termed "join-and-stream" (JAS), which broadcasts a movie in a staggered manner and uses short unicast streams to recover the time difference between the broadcast point and the arrival time. We show that such a technique is effective for movies with intermediate arrival rate. We then propose a broadcasting scheme for popular movies termed "stream-bundling". The scheme groups (i.e., "bundles") the server streams into channels of incrementally increasing bandwidth. Such high-speed bundled channels are used to deliver the beginning portion of the videos to the clients, so that the clients can merge with an on-going broadcast stream quickly. By comparing with other previously proposed broadcasting schemes (such as Pyramid Broadcasting, Skyscraper Broadcasting and Harmonic Broadcasting), stream-bundling is shown to achieve similar level of performance with much lower complexity (without many channels to manage and to hop). Using our two schemes, the bandwidth requirement of a system can be reduced significantly (by more than 50% in our examples) as compared with the traditional NVOD, with the cost of only a little client buffering, (≤20% of the movie length).