Recently, video streaming services using P2P (Peer-to-Peer) have attracted attention to solve the problem of load concentration on servers and to reduce large latency. Many P2P streaming systems, like Coolstreaming, however, take a complicated approach to control playback timing severely. This leads to less churn resiliency and less adaptability to fluctuation of network traffic. Therefore, we focus on a simple and robust approach to realize “pseudo” streaming with high quality, which is based on BitTorrent. In the existing methods with the simple approach, peers download pieces just closer to playback timing to decrease the playback discontinuity. However, these methods do not consider the constitution of video structure in sophisticated manner. P2P streaming system must consider several important metrics for high-quality and fair distribution. Therefore, in this paper, we propose a new P2P video streaming system considering the cooperation of three important metrics; video structure, playback timing, and piece dispersion on network. In this system, users vary three piece selections to suit the delivery status. Specifically, users preferentially download pieces which affect the video quality, which are closer to playback timing, and which improve the delivery efficiency. Moreover, we show the effectiveness of the proposed method by computer simulation.

Overlay networks, such as P2P, Grid, and CDN, have been widely deployed over physical IP networks. Since simultaneous overlay networks compete for network resources, their selfish behaviors to improve their application-oriented QoS disrupt each other. To enhance the collective performance and improve the QoS at the application level, we consider so-called the overlay network symbiosis where overlay networks cooperate with each other. In this paper, we proposed a cooperative mechanism for hybrid P2P file-sharing networks, where peers can find more files and exchange files with more peers. Through simulation experiments, we verified the effectiveness of cooperation from view points of application and system.