Multi-Access Coded Caching With Optimal Rate and Linear Subpacketization Under PDA and Consecutive Cyclic Placement

This work considers the multi-access caching system proposed by Hachem et al., where each user has access to
$L$
neighboring caches in a cyclic wrap-around fashion. We first propose a placement strategy called the consecutive cyclic placement, which achieves the maximal local caching gain. Then under the consecutive cyclic placement, we derive an upper bound on the coded caching gain of any PDA, thus obtaining a lower bound on the rate of PDA-based coded caching schemes. Finally, we construct a class of PDAs under the consecutive cyclic placement, leading to a multi-access coded caching scheme with linear subpacketization, which achieves the derived lower bound on the rate for some parameters; while for other parameters, the achieved coded caching gain is only 1 less than the derived upper bound on the coded caching gain. Analytical and numerical comparisons of the proposed scheme with existing schemes are provided to validate the performance.