This paper investigates PASS-enabled downlink covert communication in the presence of distributed surveillance, where multiple wardens perform signal detection and fuse their local binary decisions via majority-voting rule. We consider a dual-waveguide architecture that simultaneously delivers covert information and randomized jamming to hide the transmission footprint, incorporating three representative PASS power-radiation laws-general, proportional, and equal. To characterize the system-level detectability, we derive closed-form expressions for local false-alarm and miss-detection probabilities. By leveraging a probability-generating-function (PGF) and elementary-symmetric-polynomial (ESP) framework, combined with a breakpoint-based partition of the threshold domain, we obtain explicit closed-form characterizations of the system-level detection error probability (DEP) under non-i.i.d. majority-voting fusion. Building on this analytical framework, we formulate a robust optimization problem to maximize the average covert rate subject to covertness constraint. To solve the resulting nonconvex design, we develop an MM-BCD-SCA algorithm that produces tractable alternating updates for power/radiation variables and PA positions via convex surrogates and inner approximations of the DEP value function. Numerical results validate the theoretical analysis and demonstrate the impact of cooperative monitoring and PASS radiation laws on the covertness-rate tradeoff.

翻译：本文研究了存在分布式监视情况下基于PASS的下行隐蔽通信系统，其中多个看守节点执行信号检测并通过多数表决规则融合其本地二元判决。我们采用一种双波导架构，可同时传输隐蔽信息与随机化干扰以隐藏传输踪迹，并整合了三种典型的PASS功率辐射定律——通用型、比例型与等功率型。为刻画系统级可检测性，我们推导了本地虚警概率与漏检概率的闭式表达式。通过结合概率生成函数与初等对称多项式框架，并采用基于断点的阈值域划分方法，我们获得了非独立同分布多数表决融合下系统级检测错误概率的显式闭式表征。基于此分析框架，我们构建了在隐蔽性约束下最大化平均隐蔽速率的鲁棒优化问题。为解决由此产生的非凸设计问题，我们开发了MM-BCD-SCA算法，该算法通过构建检测错误概率值函数的凸替代函数与内逼近，为功率/辐射变量及功率放大器位置生成可处理的交替更新方案。数值结果验证了理论分析，并揭示了协同监测机制与PASS辐射定律对隐蔽性-速率权衡关系的影响。