Optimal hierarchical deployment of caches for video streaming

Despite an intensive and long-lasting effort from the scientific community, the dynamic behavior of a single cache is still hard to model and work around hierarchy or federation of caches has barely started. As a result, it is very difficult to predict the potential benefit that one could gain from a cache in a real setting and network operators lack efficient tools to decide whether or not to deploy a caching architecture. In this paper, we propose a tractable optimization model whose aim is to decide where to deploy caches and to fine-tune the caching parameters and architecture in order to maximize the overall benefit (measured as the difference between the bandwidth saved in the network and the cost of the caching architecture). The dynamic behavior of caches is taken into account in a simple way by considering blocks of contents ordered according to their popularities. The model we propose also allows to include streaming capacity of a cache (a feature that is most often omitted in cache location models). Some results over series of randomly generated instances are reported.