Supplier Selection Strategy And Simulation Based On Cache State For Proxy Assistant P2P-VoD System

Being the hotspot in the industry, Streaming Media technology has aroused general concern as the age of multimedia communication arriving. And VoD which provides interactive services has been one of the most important network multi-media services in various applications of streaming media.Various streaming media systems based on C/S model, IP multicast and CDN technology were presented for the extensive VoD services on Internet. Peer to peer (P2P) technology has been the popular application as the spotlight of the industry in recent years, and VoD system based on P2P is one of the most potential technologies in streaming applications. This paper was around such issues in the process of providing streaming service in the system: choosing peer, scheduling streaming media data in multi-peer, and providing fair QoS to each customer who requests the same content. Also the validity of algorithms will be testified by network simulation in most streaming media theoretical researches. So the problem how to enhance the reliability of simulation is drawing more and more attentions from academics. The valid proposal for those problems is just as below.First of all, the peer cache status was proposed to analyze the streaming media service of P2P-VoD system. Most existing peer selection strategies mean choosing the service providers from the peers which already have cached the whole segment of media data, which has the feature that the number of peers providing services in the system will go down as the number of requestors go up. So it would get very different EBR(Expected Bit Rate) when the requests that arrive successively in a period of time ask for the same segment of media.Resolving the above problem with no fair, we presented a peer selection strategy called DRPS(Data Receiving Peers as Suppliers), which can increase the number of service peers quickly by saving the time for common Peers to be service peer because it chooses the service provider from RS(Receiving Set)peers receiving media data in prior. The resource and availability of peers will be both considered, and the service capability of peers will be evaluated through designed mathematical model in this strategy.While providing service, the peers in RS only have part of media data cached, which needed to be preassigned by the preassignment scheduling algorithm that resolves the scheduling problem of media data in multi-peer for DRPS strategy. Comparing with past researches, the new points in my research just as below:(1) Analyzing the streaming media service of P2P-VoD system with respect to the peer cache status.(2) Suggesting the DRPS strategy that chooses the RS peers who are receiving media data as candidate service providers.(3) Designing the preassignment scheduling algorithm that schedule the data of service-providing peers chosen by DRPS strategy.The performance of DRPS strategy and preassignment scheduling algorithmwill be testified by network video simulation with NS-2 tool, and will also be compared with other algorithms. In order to validate the reliability and credibility of this research, this paper inserts MPEG-2 video code stream into the NS-2 simulated environment. When the simulating work ends, the grouping information that client has received will be translated into video files. So we can compare the quality of different services with media player directly, and also get the specific data of client EBR and delay in the playing. Finally, the validity of DRPS strategy and algorithm are proved by the analysis of simulation result.