Optimization Of Heterogeneous Caching Systems With Rate Limited Links

This paper considers centralized coded caching, where the server not only designs the users' cache contents, but also assigns their cache sizes under a total cache memory budget. The server is connected to each user via a link of given finite capacity. For given link capacities and total memory budget, we minimize the worst-case delivery completion time by jointly optimizing the cache sizes, the cache placement and delivery schemes. The optimal memory allocation and caching scheme are characterized explicitly for the case where the total memory budget is smaller than that of the server library. Numerical results confirm the savings in delivery time obtained by optimizing the memory allocation.