On The Content Distribution Strategies In Peer-to-Peer Vedio-on-Demand Systems

With the increment of the link capacity offered to Internet users, Video on Demand (VoD) services is becoming more and more popular. Users'requirements for video quality are higher and higher. The growing user demand makes all of the existing solution for P2P VoD inefficient. P2P streaming technology is a feasible solution for a large scale P2P VoD system because it can take advantage of all the peers'resources, and greatly reduce the server load and cost. Currently, P2P VoD technology has attracted wide attention.In this paper, we first introduce and analyze the content distribution technologies of the existing P2P VoD system, and compare the advantages and disadvantages of different distribution strategies. Then we thoroughly study the content distribution technologies from the aspects of request end, the response end and the use of spare nodes in the network, and give a feasible proposal respectively.The push-pull combination content distribution strategy is general applied to live systems because of its limitation such as redundant packets, poor dynamic adaptability and so on. The dissertation proposes a push-pull combination content distribution strategy for VoD systems. Through dividing of the scheduling buffer, the proposed scheme overcomes the problems of redundant packets. At the same time, the dynamically adjusting the scheduling bandwidth and the migration of fragment-orders make the more responsive to dynamic demand systems and for the condition of discontinuous buffer at peers. Experiments show that the proposed scheme can better adapt to the environment of the video-on-demand systems.Almost all previous scheduling strategies adopt simple strategies at response end, which make it could not achieve expected goals. In this paper, we take the urgency and rarity of the request data blocks, as well as the bandwidth of request peers into consideration, and propose a data scheduling strategy based on response control mechanism (DSBRC). The experimental results show that DSBRC can perform better on several performance indexes than the exist strategies.The throughput of P2P VoD systems is typically capped by the users'aggregate upload bandwidth. Motivated by this, we introduce helper into P2P VoD system. And study how to fully utilize the resources of helper nodes. The dissertation proposed a P2P VoD solution based on helpers. The simulation results show that the proposed scheme can effectively utilize helpers'spare upload capacity, and can support large-scale on-demand services with relative low server load in the condition of lower ratio of upload bandwidth provided.