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：本文研究多天线配置下的多接入编码缓存网络，其中每个用户可访问多个缓存节点。该网络包含$K$个用户与$K$个缓存单元，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$M/N \leq 1$。单天线服务器的循环环绕多接入编码缓存网络已有深入研究，现有文献提出了多种编码缓存方案并改进了性能下界。然而，编码缓存领域尚未在多天线配置下对此类网络进行系统研究。本文针对多天线多接入编码缓存问题，通过构建缓存阵列与传输阵列的组合提出解决方案。针对不同场景提出三种阵列构造方法，并据此设计相应的多天线多接入编码缓存方案。其中两种方案在未编码放置与单次传输条件下达到最优性能，其最优性通过将多天线多接入编码缓存方案与具有相同用户数、且每个用户具有$rM/N$归一化缓存容量的专用缓存网络最优多天线方案进行性能匹配得以证明。特别地，所提方案中的一种特殊情形可涵盖现有单天线配置下的最优多接入编码缓存方案。