Integrating coded caching (CC) into multiple-input multiple-output (MIMO) communications can significantly enhance the achievable degrees of freedom (DoF) in wireless networks. This paper investigates a practical cache-aided asymmetric MIMO configuration with cache ratio $\gamma$, where a server equipped with $L$ transmit antennas communicates with $K$ users, each having $G_k$ receive antennas. We propose three content-aware MIMO-CC strategies: the \emph{min-G} scheme, which treats the system as symmetric by assuming all users have the same number of antennas, equal to the smallest among them; the \emph{Grouping} scheme, which maximizes spatial multiplexing gain separately within each user subset at the cost of some global caching gain; and the \emph{Phantom} scheme, which dynamically redistributes spatial resources using virtual or ``phantom'' antennas at the users, bridging the performance gains of the min-$G$ and Grouping schemes. These strategies jointly optimize the number of users, $\Omega$, and the parallel streams decoded by each user, $\beta_k$, ensuring linear decodability for all target users. Analytical and numerical results confirm that the proposed schemes achieve significant DoF improvements across various system configurations.

翻译：将编码缓存技术集成到多输入多输出通信中，能够显著提升无线网络的可实现自由度。本文研究了一种具有缓存比例$\gamma$的实用缓存辅助非对称MIMO配置，其中配备$L$根发射天线的服务器与$K$个用户通信，每个用户拥有$G_k$根接收天线。我们提出了三种内容感知的MIMO-CC策略：\emph{最小G}方案，该方案通过假设所有用户具有相同天线数（等于其中最小值）将系统视为对称系统；\emph{分组}方案，该方案以牺牲部分全局缓存增益为代价，分别在每个用户子集内最大化空间复用增益；以及\emph{幻影}方案，该方案通过在用户端使用虚拟或“幻影”天线动态重新分配空间资源，从而桥接最小$G$方案与分组方案的性能增益。这些策略联合优化了用户数量$\Omega$和每个用户解码的并行流数量$\beta_k$，确保所有目标用户具有线性可解码性。解析与数值结果证实，所提方案在各种系统配置下均能实现显著的自由度提升。