Unlike conventional fixed-antenna architectures, rotatable antenna (RA) has shown great potential in enhancing wireless communication performance by exploiting additional spatial degrees of freedom (DoFs) in a cost-effective manner. In this letter, we propose a novel RA-enabled covert communication system, where an RA array-based transmitter (Alice) sends covert information to a legitimate user (Bob) in the presence of multiple wardens (Willies). To maximize the covert rate, we optimize the transmit beamforming vector and the rotational angles of individual RAs, subject to the constraints on covertness, transmit power, and antenna rotational range. To address the non-convex formulated problem, we decompose it into two subproblems and propose an efficient alternating optimization (AO) algorithm to solve the two subproblems iteratively, where the second-order cone programming (SOCP) method and successive convex approximation (SCA) approach are applied separately. Simulation results demonstrate that the proposed RA-enabled covert communication system can provide significantly superior covertness performance to other benchmark schemes.

翻译：与传统固定天线架构不同，可旋转天线通过以经济高效的方式利用额外的空间自由度，在提升无线通信性能方面展现出巨大潜力。本文提出一种新颖的可旋转天线赋能隐蔽通信系统，其中基于可旋转天线阵列的发射机（Alice）在存在多个监测者（Willies）的情况下向合法用户（Bob）发送隐蔽信息。为最大化隐蔽速率，我们在隐蔽性、发射功率及天线旋转范围约束下，优化发射波束成形向量与各可旋转天线的旋转角度。针对该非凸优化问题，我们将其分解为两个子问题，并提出一种高效的交替优化算法进行迭代求解，其中分别应用了二阶锥规划方法与逐次凸逼近技术。仿真结果表明，所提出的可旋转天线赋能隐蔽通信系统相比其他基准方案能提供显著更优的隐蔽性性能。