Research And Design Of P2P VoD System Based On Optimal Hybrid Scheduling Strategy

In recent years, streaming media systems are more and more popular and have become a hot research topic of computer network. Currently, P2P live streaming systems are becoming more mature, but P2P video-on-demand systems are still in the initial stage. The analysis and comparison to the existing P2P streaming architectures show that the mesh multicast architecture based on gossip protocol is more reliable and scalable than the traditional tree multicast architecture.After analyzing the key techniques of P2P streaming, started off from the point of the mesh multicast architecture based on gossip protocol, this thesis designs a P2P video-on-demand system OPVoD that adopts a series of optimal hybrid scheduling strategies. It makes the overall design to OPVoD system architecture, illustrates the main modules in the tracker and peer subsystem, and discusses in depth the peer subsystem and the key techniques therein.In the design of OPVoD system, this thesis employs a hybrid scheduling strategy based on optimization, and adopts a series of key techniques. The anchor peers are introduced and the resource locating mechanism combined with tracker servers and using the technique of random walks can lighten the burden on the servers and meanwhile ensure a quick resource locating. Using the mechanism of combined initial buffer, dynamic buffer, pre-fetch buffer and the hard disk storage can increase the hit rate of data block greatly. The push-pull protocol based on segments can reduce the propagation delay significantly. The data pre-fetching mechanism based on anchor peers considers the user's history behavior and the popularity of data blocks comprehensively. The local optimal urgent downloading scheduling algorithm and the timeout handling stategy based on the priority can improve the playback continuity.In the end, P2PStrmsim is selected as the basic simulation platform and based on P2PStrmsim, this thesis has made simulation design and implemention to OPVoD system, and the performance testing to the system has been conducted. The results show that after adopting a series of optimal hybrid scheduling strategies, the startup delay, playback quality and the other performance indicators of OPVoD system have shown the superiority.