A movable antenna (MA)-enabled secure multiuser transmission framework is developed to enhance physical-layer security. Novel expressions are derived to characterize the achievable sum secrecy rate based on the secure channel coding theorem. On this basis, a joint optimization algorithm for digital beamforming and MA placement is proposed to maximize the sum secrecy rate via fractional programming and block coordinate descent. In each iteration, every variable admits either a closed-form update or a low-complexity one-dimensional or bisection search, which yields an efficient implementation. Numerical results demonstrate the effectiveness of the proposed method and show that the MA-enabled design achieves higher secrecy rates than conventional fixed-position antenna arrays.

翻译：提出了一种基于可移动天线（MA）的安全多用户传输框架，用于增强物理层安全性。基于安全信道编码定理，推导了表征可实现和保密速率的新表达式。在此基础上，提出了数字波束成形与MA位置联合优化算法，通过分数规划和块坐标下降法最大化和保密速率。每次迭代中，每个变量均可获得闭式解或低复杂度的一维/二分搜索更新，从而实现高效的计算。数值结果验证了所提方法的有效性，并表明基于MA的设计相比传统固定位置天线阵列能够实现更高的保密速率。