Centralized Coded Caching with Heterogeneous Cache Sizes

Coded caching can improve fundamental limits of communication, utilizing storage memory at individual users. This paper considers a centralized coded caching system, introducing heterogeneous cache sizes at the users, i.e., the users' cache memories are of different size. The goal is to design cache placement and delivery policies that minimize the worst-case delivery load on the server. To that end, the paper proposes an optimization framework for cache placement and delivery schemes which explicitly accounts for the heterogeneity of the cache sizes. We also characterize explicitly the optimal caching scheme, for the case where the sum of the users' cache sizes is smaller than or equal to the library size.