Centralized Caching with Shared Caches in Heterogeneous Cellular Networks

We consider heterogeneous cellular networks, where cache-enabled small base stations help a macro base station by serving users within subareas of the macro base station's coverage area. We model the network by a centralized caching problem with shared caches, consisting of a server (representing a macro base station) broadcasting messages to users through a shared error-free link, where each user pair shares two caches (representing two small base stations covering the subarea of these two users). We propose caching schemes with uncoded cache placement using the idea of incremental caching, with an aim to minimize the load of worst-case demands over the shared link. Our caching schemes prove to be useful when the sets of users served by different caches have a non-empty intersection.