Integrating coded caching (CC) techniques into multi-input multi-output (MIMO) setups provides a substantial performance boost in terms of the achievable degrees of freedom (DoF). In this paper, we study cache-aided MIMO setups where a single server with $L$ transmit antennas communicates with a number of users each with $G$ receive antennas. We extend a baseline CC scheme, originally designed for multi-input single-output (MISO) systems, to the considered MIMO setup. However, in a proposed MIMO approach, instead of merely replicating the transmit strategy from the baseline MISO scheme, we adjust the number of users served in each transmission to maximize the achievable DoF. This approach not only makes the extension more flexible in terms of supported network parameters but also results in an improved DoF of $\max_{\beta \le G} \beta \lfloor \frac{L-1}{\beta} \rfloor + \beta (t+1)$, where $t$ is the coded caching gain. In addition, we also propose a high-performance multicast transmission design for the considered MIMO-CC setup by formulating a symmetric rate maximization problem in terms of the transmit covariance matrices for the multicast signals and solving the resulting non-convex problem using successive convex approximation. Finally, we use numerical simulations to verify both improved DoF results and enhanced MIMO multicasting performance.

翻译：将编码缓存（CC）技术集成到多输入多输出（MIMO）系统中，可显著提升可达自由度（DoF）性能。本文研究缓存辅助MIMO系统，其中配备$L$根发射天线的服务器与多个用户通信，每个用户配备$G$根接收天线。我们将最初为多输入单输出（MISO）系统设计的基线CC方案扩展到所考虑的MIMO场景。然而，在所提出的MIMO方法中，我们并非简单复制基线MISO方案的传输策略，而是调整每次传输中服务的用户数量以最大化可达自由度。该方法不仅使扩展方案在支持的网络参数方面更具灵活性，还实现了$\max_{\beta \le G} \beta \lfloor \frac{L-1}{\beta} \rfloor + \beta (t+1$的改进自由度，其中$t$为编码缓存增益。此外，我们通过构建关于多播信号发射协方差矩阵的对称速率最大化问题，并采用逐次凸近似方法求解所得非凸问题，提出了一种面向MIMO-CC场景的高性能多播传输设计方案。最后，数值仿真验证了改进的自由度结果和增强的MIMO多播性能。