Coded Cache Placement for Heterogeneous Cache Sizes

Abstract

We focus on the coded caching problem of N files and K users with heterogeneous cache sizes. By utilizing coded caching placement, we improve upon existing schemes in terms of the delivery rate. This is done by first finding an optimal caching and delivery scheme for some special heterogeneous-cache-size cases where L out of K users has no cache and the other $K-L$ users are each equipped with a cache of size $N-L$. The optimal caching and delivery scheme exploits the Cauchy matrix and its properties. Next, memory-sharing between the special heterogeneous-cache-size points and existing equal/unequal-cache-size points are performed. Through numerical results, we demonstrate the gain of the proposed scheme to existing schemes for heterogenous cache sizes.