Surveillance performance is studied for a wireless eavesdropping system, where a full-duplex legitimate monitor eavesdrops a suspicious user’s link with artificial noise (AN) assistance. Different from the existing works, the suspicious receiver is assumed to be capable of detecting the presence of AN. Once such receiver detects the AN, the suspicious user will stop transmission, which can therefore degrade the surveillance performance. Hence, to improve the surveillance performance, AN should be transmitted covertly with a low detection probability. Under these assumptions, an optimization problem is formulated to maximize the surveillance performance under a covert constraint. Then, based on the detection ability at the suspicious receiver, a novel scheme is proposed to solve the optimization problem using an iterative search. Moreover, we investigate the impact of both the suspicious-transmitter-to-suspicious-receiver and the monitor-to-suspicious-receiver links uncertainties on the covert surveillance performance. Simulations are performed to verify the analyses. We show that the uncertainty in the suspicious user’s link can enhance the surveillance performance, while the uncertainty in the monitor-to-suspicious-receiver link can degrade the surveillance performance.

中文翻译：

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在信道不确定性下通过主动窃听进行隐蔽监视

研究了无线窃听系统的监视性能，其中全双工合法监视器通过人工噪声 (AN) 辅助窃听可疑用户的链接。与现有工作不同，假设可疑接收器能够检测到 AN 的存在。一旦此类接收器检测到 AN，可疑用户将停止传输，从而降低监控性能。因此，为了提高监视性能，AN 应该以低检测概率秘密传输。在这些假设下，优化问题被公式化以在隐性约束下最大化监视性能。然后，基于可疑接收器的检测能力，提出了一种使用迭代搜索解决优化问题的新方案。而且，我们调查了可疑发射机到可疑接收机和监视器到可疑接收机链接的不确定性对隐蔽监视性能的影响。执行模拟以验证分析。我们表明，可疑用户链接中的不确定性可以提高监视性能，而监视器到可疑接收者链接中的不确定性会降低监视性能。