Coded Caching with Shared Caches: Fundamental Limits with Uncoded Prefetching
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The work identifies the fundamental limits of coded caching when the K receiving users share Λ≤ K helper-caches, each assisting an arbitrary number of different users. The main result is the derivation of the exact optimal worst-case delivery time - under the assumption of uncoded cache placement - for any user-to-cache association profile, i.e., irrespective of how many users are served by each cache. This is achieved with a new information-theoretic converse that is based on index coding and which proves that a simple XOR-shrinking-and-removal coded-caching scheme is optimal irrespective of the user-to-cache association profile.
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