Multi-access coded caching: gains beyond cache-redundancy

The work considers the K-user cache-aided sharedlink 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+Kγ (users served at a time) despite the fact that the total cache redundancy remains Kγ irrespective of z. Interestingly, when z = (κ-1)/(Kγ), the derived optimal coding gain is Kγz + 1, matching the performance of a hypothetical scenario where each user has its own dedicated cache of size zγ.