Cache-Aided Combination Networks with Asymmetric End Users

We study combination networks where a layer of relay nodes connects a server to a set of end users with cache memories via unicast links. Unlike previous models on cache-aided combination networks where all users are connected to the same number of relay nodes, in this work, we consider two classes of end users, where users from the same class are connected to the same number of relay nodes. Using maximum distance separable (MDS) codes, we provide a coded caching scheme by jointly optimizing the cache placement and the delivery phase in order to minimize the delivery load over the two hops. The scheme is performed over two stages. In the first stage, we serve users from both classes, then during the second stage, we serve users from the class connected to a smaller number of relays. We extend the proposed scheme to networks with more than two classes of end users.