Performance of Covert Surveillance via Proactive Eavesdropping

Surveillance performance is studied in this paper for a wireless eavesdropping system, where a full-duplex legitimate monitor eavesdrops a suspicious link efficiently with the artificial noise (AN) assistance. Different from the existing work, 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 degrades 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 eavesdropping non-outage probability under a covert constraint. 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 and the jamming links uncertainties on the covert surveillance performance. Simulations are performed to verify the analyses. We show that the suspicious link uncertainty enhances the surveillance performance, while the jamming link uncertainty can degrade the surveillance performance.