OPTIMAL VIDEO PLACEMENT FOR HIERARCHICAL VIDEO-ON-DEMAND SYSTEMS

In the past three years, we have been implementing a VOD system over A TM networks based on a hierarchical three-level network architecture. One of the most important design problems is how to organize video pro grams stored at different level of servers. In this paper, we propose an optimal video placement strategy which gives the optimal number of video copies should be stored at each level of server such that the co st function can be minimised while a lower bound of the request reject ion probability for each video is guaranteed. Our major contribution i s that we model the time-variant request arrivals as a non-homogeneous Poisson process.