关键词: P2P，重叠网，分层视频编码，流媒体系统

Abstract: Peer-to-Peer(P2P)based streaming applications hold the advantages of high efficient deployment abilitsy and high scalability. Layered video coding based P2P streaming system splits the source video into multiple layer of video data and distributes these streaming data, which makes peer can select the playback duality according to its bandwidth resource. I}his kind of streaming system is more accommodative to the heterogeneity of peers. However, difference distribution overlay path of different layer of streaming data also leads to challenges of overlay construction in layered P2P streaming system. This paper formulated the overlay construction issue in layered P2P streaming environment, which is a NP-hard problem, and put forward a centralized heuristic algorithm, then designed a streaming group based distributed overlay construction policy. Large scale network simulation shows that this overlay construction mechanism has the characteristics of comparatively low bandwidth consumption at streaming server and high streaming acquisition ratio.

Key words: P2P, Overlay network, Layered video coding, Streaming system