This work explores a multiple transmit antenna setting in a multi-access coded caching (MACC) network where each user accesses more than one cache. A MACC network has $K$ users and $K$ caches, and each user has access to $r < K$ consecutive caches in a cyclic wrap-around manner. There are $L$ antennas at the server, and each cache has a normalized size of $M/N \leq 1$. The cyclic wrap-around MACC network with a single antenna at the server has been a well-investigated topic, and several coded caching schemes and improved lower bounds on the performance are known for the same. However, this MACC network has not yet been studied under multi-antenna settings in the coded caching literature. We study the multi-antenna MACC problem and propose a solution for the same by constructing a pair of arrays called caching and delivery arrays. We present three constructions of caching and delivery arrays for different scenarios and obtain corresponding multi-antenna MACC schemes for the same. Two schemes resulting from the above constructions achieve optimal performance under uncoded placement and one-shot delivery. The optimality is shown by matching the performance of the multi-antenna MACC scheme to that of an optimal multi-antenna scheme for a dedicated cache network having an identical number of users, and each user has a normalized cache size of $rM/N$. Further, as a special case, one of the proposed schemes subsumes an existing optimal MACC scheme for the single-antenna setting.

翻译：本文探究了多接入编码缓存（MACC）网络中的多发射天线场景，其中每个用户可访问多个缓存。该MACC网络包含$K$个用户与$K$个缓存，每个用户以循环环绕方式访问$r < K$个连续缓存。服务器配备$L$根天线，每个缓存的归一化容量为$M/N \leq 1$。针对服务器配备单天线的循环环绕MACC网络，已有充分研究，并提出了多种编码缓存方案及其性能下界的改进结果。然而，在编码缓存文献中，该MACC网络尚未在多元线设置下得到研究。我们研究了多天线MACC问题，并通过构建一对称为缓存阵列与分发阵列的结构提出相应解决方案。针对不同场景，我们给出了三种缓存与分发阵列的构造方法，并据此获得对应的多天线MACC方案。其中两种方案在无编码放置与单次分发条件下达到最优性能，其最优性通过将多天线MACC方案的性能与专用缓存网络中最优多天线方案进行匹配得以证明——后者具有相同用户数，且每个用户的归一化缓存容量为$rM/N$。此外，作为特例，所提方案之一涵盖了现有单天线场景下的最优MACC方案。