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Alternate-Jamming-Aided Wireless Physical-Layer Surveillance: Protocol Design and Performance Analysis

In this article, we develop an alternate-jamming-aided wireless physical-layer surveillance protocol where two devices (M1 and M2) work cooperatively to eavesdrop on and intervene in a suspicious transmission link from a source (S) to a destination (D). Unlike existing approaches which rely on the use of a multi-antenna full-duplex radio as the monitor, in our protocol, M1 and M2 are both single-antenna nodes operating in half-duplex mode, which alternately perform proactive eavesdropping and jamming to mimic the behavior of a full-duplex monitor. Within any time slot, M1 sends a jamming signal to deteriorate the signal reception at D and M2 eavesdrops on the transmission from S. During the next slot, M1 overhears the signal sent from S, and M2 forwards its received signal during the previous slot to realize jamming. In this manner, the jamming signal received at M1 can be perfectly removed after self-interference cancellation, and the signals from S during the two consecutive slots are jointly decoded with high reliability, thus enabling successful surveillance. On the other hand, the detection performance at D is heavily degraded due to the injection of the jamming signal, thereby preventing information leakage from S to D. The performance of the proposed protocol is analyzed in terms of the eavesdropping non-outage probability, the surveillance success probability, as well as the symbol error probability. Theoretical analysis and simulation results demonstrate the superiority of our design compared to competing solutions in the literature.