A Cache Scheduling Scheme Based on Layered Coding VOD System

Internet video on demand is a new application provided by peer to peer network. Thousands of users are using real multimedia streaming systems like PPlive and PPstream which are the killer applications in the Internet. But jitters are always happening during rush time especially when users are watching less popular videos with low bandwidth network. To improve this, a cache scheduling scheme based on layered coding is proposed in this paper. Our scheme aims at optimizing cache scheduling scheme in peers´ local cache while other researches often focus on the proxy server. The available bandwidth considered as energy is allocated by Fermi distribution function for different layer data of FGS, and the prefix buffer is extended dynamically. When the available bandwidth is insufficient, peers are forced to allocate more bandwidth for base layer data, and their prefix buffer is extended so that more base layer data is downloaded for users who watch a video continuously and with interactive operations. Simulation shows that our approach reduces cache missing rate effectively when available bandwidth is insufficient. In local cache, peers replace segments in the cache by formulas of popularity which is proposed to reduce cache missing rate more successful. In general, our scheme can effectively reduce starting delay and times of jitters in a multimedia system with low bandwidth.