Towards the optimal caching strategies of peer-assisted VoD systems with HD channels

In this paper, we propose a modeling framework to capture the major characteristics of peer-assisted video ondemand systems offering standard and high-definition channels. Our framework can be extended to model a variety of caching strategies, including FIFO, passive caching, and active caching. We use the framework to prove that passive caching is sufficiently effective for stationary user behaviors, and generate the optimal caching solutions when the channels in the system demonstrate different popularity evolutions, i.e., with non-stationary behaviors. Simulation results verify the efficacy of our active-caching strategy and provide further insights into such systems that are gaining more popularity over the Internet.