A movable antennas (MAs)-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：本文提出了一种基于可移动天线（MAs）的安全多用户传输框架，以增强物理层安全性。基于安全信道编码定理，推导了新颖的表达式来刻画可达的总和保密速率。在此基础上，提出了一种数字波束成形与MA位置联合优化算法，通过分式规划和块坐标下降法最大化总和保密速率。在每次迭代中，每个变量均存在闭式更新解或可通过低复杂度的一维搜索或二分搜索求解，从而实现了高效的计算。数值结果验证了所提方法的有效性，并表明基于MA的设计相比传统的固定位置天线阵列能够获得更高的保密速率。