This paper investigates covert communications in an integrated sensing and communications system, where a dual-functional base station (called Alice) covertly transmits signals to a covert user (called Bob) while sensing multiple targets, with one of them acting as a potential watcher (called Willie) and maliciously eavesdropping on legitimate communications. To shelter the covert communications, Alice transmits additional dual-functional artificial noise (DFAN) with a varying power not only to create uncertainty at Willie's signal reception to confuse Willie but also to sense the targets simultaneously. Based on this framework, the weighted sum of the sensing beampattern means square error (MSE) and cross correlation is minimized by jointly optimizing the covert communication and DFAN signals subject to the minimum covert rate requirement. The robust design considers both cases of imperfect Willie's CSI (WCSI) and statistical WCSI. Under the worst-case assumption that Willie can adaptively adjust the detection threshold to achieve the best detection performance, the minimum detection error probability (DEP) at Willie is analytically derived in the closed-form expression. The formulated covertness constrained optimization problems are tackled by a feasibility-checking based difference-of-convex relaxation (DC) algorithm utilizing the S-procedure, Bernstein-type inequality, and the DC method. Simulation results validate the feasibility of the proposed scheme and demonstrate the covertness performance gains achieved by our proposed design over various benchmarks.

翻译：本文研究了集成感知与通信系统中的隐蔽通信问题，其中双功能基站（称为Alice）在感知多个目标的同时，向隐蔽用户（称为Bob）秘密传输信号，而其中一个目标作为潜在监视者（称为Willie）恶意窃听合法通信。为掩护隐蔽通信，Alice发射功率可变的双功能人工噪声，一方面在Willie的信号接收端制造不确定性以干扰其检测，另一方面同时用于感知目标。基于此框架，通过联合优化隐蔽通信信号与双功能人工噪声，在满足最小隐蔽速率约束条件下最小化感知波束方向图均方误差与互相关的加权和。鲁棒设计同时考虑Willie信道状态信息不完美与统计信道状态信息两种情况。在最坏情况下假设Willie能够自适应调整检测阈值以获取最优检测性能，推导出Willie端最小检测错误概率的闭式表达式。利用S过程、伯恩斯坦不等式及DC方法，提出基于可行性检测的差凸松弛算法求解所构建的隐蔽约束优化问题。仿真结果验证了所提方案的可行性，并表明本设计相较于各类基准方案取得的隐蔽性能增益。