发表机构
University College London; Concordia University（伦敦大学学院; 康考迪亚大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文研究E-FAS信道结构对隐蔽通信的影响，证明监视者最优检测为能量检测，并发现有限模式信道可提升隐蔽性，且信道硬化对合法链路与隐蔽性具有不对称作用。
AI 中文摘要
巨型流体天线系统（E-FAS）能够实现导引表面波（SW）传播，并产生一个条件复高斯端到端信道，其协方差尺度是随机的。本文研究了在存在被动监视者的情况下，这种信道结构对隐蔽通信的影响。在等功率有效模式表示下，随机信道尺度服从伽马分布，导致有效信道功率服从贝塞尔-K分布。我们证明，监视者的最优似然比检验简化为能量检测器，并推导了相应的虚警概率和漏检概率。这些结果随后用于在规定的检测错误约束下刻画可实现的隐蔽吞吐量。数值结果表明，对于有限观测区间，有限模式E-FAS信道相对于具有相同平均信道功率的完全硬化瑞利极限提高了隐蔽性。结果还揭示了信道硬化的不对称作用：更强的硬化可以改善合法链路，而在监视者处保留信道尺度波动可以增强有限观测下的隐蔽性。
英文摘要
Enormous fluid antenna systems (E-FAS) enable guided surface wave (SW) propagation and induce an end-to-end channel that is conditionally complex Gaussian with a random covariance scale. This paper investigates the impact of this channel structure on covert communication in the presence of a passive warden. Under an equal power effective mode representation, the random channel scale follows a Gamma distribution, leading to a Bessel-K distribution for the effective channel power. We show that the optimal likelihood ratio test at the warden reduces to an energy detector and derive the corresponding false alarm and missed detection probabilities. These results are then used to characterize the achievable covert throughput under a prescribed detection error constraint. Numerical results show that, for finite observation intervals, finite mode E-FAS channels improve covertness relative to the fully hardened Rayleigh limit with the same average channel power. They further reveal an asymmetric role of channel hardening: stronger hardening can improve the legitimate link, whereas retaining channel scale fluctuations at the warden can enhance finite observation covertness.
