Optimised local caching in cellular mobile networks

Motivated by the problem of increasing backhaul transmission costs in cellular mobile networks we examine the potential of highly distributed caching solutions. In particular we propose to overcome the problem of poor hit ratios in such solutions by forming caching domains which support pooling (the ability to fetch content from other caches when necessary) and equalisation (active transfers between caches to preload popular content). The characteristics of such a scheme are investigated by applying a new analytical model to a set of realistic examples. The model is verified against both computer based simulations and measurements in a real network, and it is found that the proposed scheme can reduce backhaul bandwidth requirements for an average cell inside a domain by a factor of 7 for web-like traffic and by a factor of 45 for video-like traffic, while the corresponding factors outside a domain amount to 41 and 997 respectively.