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 $γ$, 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, $Ω$, and the parallel streams decoded by each user, $β_k$, 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（CC）技术融入多输入多输出（MIMO）通信可显著提升无线网络的可实现自由度（DoF）。本文研究一种具有缓存比例$γ$的实用缓存辅助非对称MIMO配置：配备$L$根发射天线的服务器与$K$个用户通信，每个用户配备$G_k$根接收天线。我们提出三种内容感知的MIMO-CC策略：\emph{min-G}方案将系统视为对称配置，假设所有用户天线数等于其中最小值；\emph{分组}方案在各用户子集内最大化空间复用增益，但会损失部分全局缓存增益；\emph{幻影}方案通过在用户端动态重分配空间资源（采用虚拟或“幻影”天线），弥合了min-$G$方案与分组方案之间的性能差距。这些策略联合优化用户数量$Ω$与各用户解码的并行数据流数$β_k$，确保所有目标用户具备线性可解码性。解析与数值结果证实，所提方案在不同系统配置下均能实现显著的DoF提升。