Abstract: This paper proposes a two-layer-relation prefetching strategy to effectively reduce latency problem when taking VCR operations in P2P VoD system. According to the peers’ past playing records, the possible relationships among different video segments can be found, which can be used for prefetching operations. It also optimizes the peer’s neighbor list to promote locating and prefetching resources. Experimental results show that the strategy can effectively prefetch data, reduce the latency caused by VCR and improve users’ viewing experience.

Key words: P2P VoD, prefetching, segment relation, peer relation, playing records

摘要： 针对如何有效降低P2P VoD系统发生VCR操作时产生的时延问题，提出了一种P2P VoD系统中的两层关系预取策略，根据节点的播放记录找到片段之间可能存在的关系，以此为依据进行预取，并对节点的邻居列表进行优化，使之能更快定位和预取资源。仿真实验结果表明，两层关系策略准确地预取了视频内容，降低了VCR时产生的时延，提高了用户的观看体验。

关键词: P2P VoD系统, 预取, 片段关系, 节点关系, 播放记录