Coded caching schemes for multi-access topologies via combinatorial design theory

This paper studies a novel multi-access coded caching (MACC) model where the topology between users and cache nodes is a generalization of those already studied in previous work, such as combinatorial and cross-resolvable design topologies. Our goal is to minimize the worst-case transmission load in the delivery phase from the server over all possible user requests. By formulating the access topology as two classical combinatorial structures, t-design and t-group divisible design, we propose two classes of coded caching schemes for a flexible number of users, where the number of users can scale linearly, polynomially or exponentially with the number of cache nodes. In addition, our schemes can unify most schemes for the shared link network and unify many schemes for the multi-access network except for the cyclic wrap-around topology.