发表机构
Chongqing University of Posts and Telecommunications; The Hong Kong University of Science and Technology; National University of Defense Technology（重庆邮电大学; 香港科技大学; 国防科技大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文针对MIMO隐蔽通信，提出利用极化可重构天线进行收发联合极化成形，在精确隐蔽约束下最大化可达速率，相比传统方法显著提升性能。
AI 中文摘要
隐蔽通信隐藏无线传输活动，但传统的多天线设计主要依赖空间波束成形，并可能受限于有限的空间自由度。本文研究了极化可重构天线（PRA）辅助的多输入多输出（MIMO）隐蔽通信，其中Alice和Bob分别执行发射和接收极化成形，而Willie使用垂直极化天线进行辐射测量检测。我们联合优化发射协方差矩阵以及发射和接收相移向量，以在隐蔽性和发射功率约束下最大化Bob的可达速率。在高斯信号、完美极化信道状态信息以及Willie处已知噪声功率的假设下，我们推导了他的最优辐射测量阈值和有限观测长度下的精确最小检测错误概率（DEP），并将DEP要求转化为对其接收信号功率的确定性约束。我们进一步证明，对于固定的传输设计，当观测长度趋于无穷时，正信号泄漏变得可检测。为了求解有限观测长度下的设计问题，我们开发了一种交替优化（AO）算法，该算法具有广义注水协方差更新和闭式相移更新。数值结果验证了精确DEP分析和所提算法的快速收敛性。与基于散度的充分条件相比，精确隐蔽约束允许Willie处的接收信噪比（SNR）提高0.99–1.12 dB，而联合发射和接收极化成形相对于所考虑的基准方案提供了高达53.8%的速率增益。
英文摘要
Covert communication conceals wireless transmission activity, but conventional multi-antenna designs rely mainly on spatial beamforming and can be constrained by limited spatial degrees of freedom. This paper investigates polarization-reconfigurable antenna (PRA)-aided multiple-input multiple-output (MIMO) covert communication, where Alice and Bob perform transmit and receive polarforming, respectively, and Willie uses a vertically polarized antenna for radiometric detection. We jointly optimize the transmit covariance matrix and the transmit and receive phase shift vectors to maximize Bob's achievable rate under the covertness and transmit power constraints. Under Gaussian signaling, perfect polarized channel state information, and known noise power at Willie, we derive his optimal radiometric threshold and exact minimum detection error probability (DEP) for a finite observation length, and convert the DEP requirement into a deterministic constraint on his received signal power. We further prove that, for a fixed transmission design, positive signal leakage becomes detectable as the observation length tends to infinity. To solve the design problem for a finite observation length, we develop an alternating optimization (AO) algorithm with a generalized water-filling covariance update and closed-form phase updates. Numerical results validate the exact DEP analysis and the rapid convergence of the proposed algorithm. Compared with the sufficient divergence-based condition, the exact covertness constraint permits a $0.99$--$1.12$~dB higher received signal-to-noise ratio (SNR) at Willie, while joint transmit and receive polarforming provides a rate gain of up to $53.8\%$ over the considered benchmark schemes.
Comments13 pages, 8 figures, Submitted for possible publication in an IEEE journal
