A Novel Caching Mechanism for P2P Video-on-Demand Systems

Providing scalable video services in a peer-to-peer (P2P) environment is challenging. In this paper we formulize the QoS (quality-of-service)-aware replication problem for P2P video-on-demand (VoD)systems, the goal of which is to satisfy access time deadlines for all nodes while maximize the probability of the successful block requests. A novel caching mechanism was proposed to achieve the goal, which includes a prefetching algorithm and a cache replacement algorithm. In particular, emergency level De and contribution degree Dc of blocks were defined, and were used in both algorithms to decide which block should be requested or removed. Simulation results show that our mechanism is effective in suppressing the playback delay and reducing the workload of server with a media stream of the desired quality comparing to another existing approach.