This paper studies a novel movable antenna (MA)-enhanced multiple-input multiple-output (MIMO) system to leverage the corresponding spatial degrees of freedom (DoFs) for improving the performance of wireless communications. We aim to maximize the achievable rate by jointly optimizing the MA positions and the transmit covariance matrix based on statistical channel state information (CSI). To solve the resulting design problem, we develop a constrained stochastic successive convex approximation (CSSCA) algorithm applicable for the general movement mode. Furthermore, we propose two simplified antenna movement modes, namely the linear movement mode and the planar movement mode, to facilitate efficient antenna movement and reduce the computational complexity of the CSSCA algorithm. Numerical results show that the considered MA-enhanced system can significantly improve the achievable rate compared to conventional MIMO systems employing uniform planar arrays (UPAs) and that the proposed planar movement mode performs closely to the performance upper bound achieved by the general movement mode.

翻译：本文研究一种新型的可移动天线（MA）增强型多输入多输出（MIMO）系统，利用相应的空间自由度（DoFs）提升无线通信性能。我们旨在通过基于统计信道状态信息（CSI）联合优化MA位置与发射协方差矩阵，最大化可实现速率。为求解所涉及的设计问题，我们开发了一种适用于一般移动模式的约束随机逐次凸近似（CSSCA）算法。此外，我们提出两种简化的天线移动模式，即线性移动模式与平面移动模式，以促进高效天线移动并降低CSSCA算法的计算复杂度。数值结果表明，与采用均匀平面阵列（UPAs）的传统MIMO系统相比，所考虑的MA增强系统可显著提升可实现速率，且所提出的平面移动模式性能接近一般移动模式所实现的性能上界。