Adaptive Prefetching Scheme for Peer-to-Peer Video-on-Demand Systems with a Media Server

In this paper, we consider Peer-to-Peer Video on- Demand (P2P VoD) systems based on the Bit Torrent file sharing protocol. Since the rarest first policy adopted in the Bit Torrent protocol could not collect all pieces corresponding to a video file by their playback time, we need to develop a new piece selection rule particularly designed for P2P VoDs. In the proposed scheme, we assume the existence of a media server which can upload any piece upon request, and try to bound the load of such media server by carefully discriminating pieces to be requested, by taking into account the rareness of the pieces held by its nearby peers, estimated size of the overlay network, and the file size to be downloaded. The performance of the proposed scheme is evaluated by simulation.