Multi-access coded caching: gains beyond cache-redundancy

Abstract

The work considers the K-user cache-aided shared- link broadcast channel where each user has access to exactly z caches of normalized size γ, and where each cache assists exactly z users. For this setting, for two opposing memory regimes, we propose novel caching and coded delivery schemes which maximize the local caching gain, and achieve a coding gain larger than $ 1+K\gamma$ (users served at a time) despite the fact that the total cache redundancy remains $ K\gamma$ irrespective of z. Interestingly, when $z = \frac{K-1}{K\gamma}$, the derived optimal coding gain is $K\gamma z+1$, matching the performance of a hypothetical scenario where each user has its own dedicated cache of size $z\gamma$.