摘要
Video accelerator is developed for better user experience in video sharing websites such as YouTube. PPLive video accelerator （PPVA）, which has the largest number of users in China, is based on peer-to-peer （P2P） system. The number of videos and peers in PPVA is by orders of magnitude many times larger than which in traditional P2P video on demand （VoD） system. As a result, even though the resource is sufficient, due to unfairness assignment, the quality of service can hardly satisfy all users. In this paper, we concentrate on the assignment of the fundamental resources in PPVA： storage and bandwidth. The problem of storage assignment is formulated as a nonlinear program （NLP） regarding the number of request as a random variable. The results show that the influence of the variance of requests is not negligible and proportional approach is appropriate only when the mean is much larger than the variance. The criteria about how to locate videos to appropriate peers are also presented, taking into account constrains such as the utilization of total bandwidth, the probability of bandwidth competition and the fairness between videos. Furthermore, the heuristic algorithms of allocating upload bandwidth in centralized and distributed fashion are proposed and evaluated against a widely used strategy （equal allocation） with respect to the balance among videos. Simulation results demonstrate that both algorithms can lead to significant performance improvement.
Video accelerator is developed for better user experience in video sharing websites such as YouTube. PPLive video accelerator （PPVA）, which has the largest number of users in China, is based on peer-to-peer （P2P） system. The number of videos and peers in PPVA is by orders of magnitude many times larger than which in traditional P2P video on demand （VoD） system. As a result, even though the resource is sufficient, due to unfairness assignment, the quality of service can hardly satisfy all users. In this paper, we concentrate on the assignment of the fundamental resources in PPVA： storage and bandwidth. The problem of storage assignment is formulated as a nonlinear program （NLP） regarding the number of request as a random variable. The results show that the influence of the variance of requests is not negligible and proportional approach is appropriate only when the mean is much larger than the variance. The criteria about how to locate videos to appropriate peers are also presented, taking into account constrains such as the utilization of total bandwidth, the probability of bandwidth competition and the fairness between videos. Furthermore, the heuristic algorithms of allocating upload bandwidth in centralized and distributed fashion are proposed and evaluated against a widely used strategy （equal allocation） with respect to the balance among videos. Simulation results demonstrate that both algorithms can lead to significant performance improvement.
基金
supported by the National Basic Research Program of China (2007CB307101)
the National Natural Science Foundation of China (60672069,60772043)
