In this article, we develop an alternate-jamming-aided wireless physical-layer surveillance protocol where two devices (M ₁ and M ₂ ) 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, M ₁ and M ₂ 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, M ₁ sends a jamming signal to deteriorate the signal reception at D and M ₂ eavesdrops on the transmission from S. During the next slot, M ₁ overhears the signal sent from S, and M ₂ forwards its received signal during the previous slot to realize jamming. In this manner, the jamming signal received at M ₁ 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.

中文翻译：

---

交替干扰辅助无线物理层监视：协议设计和性能分析

在本文中，我们开发了一种备用干扰辅助的无线物理层监视协议，其中两个设备（M ₁和M ₂ ）协同工作，以窃听并干预从源（S）到目的地（ D）。与依赖于使用多天线全双工无线电作为监视器的现有方法不同，在我们的协议中，M ₁和M ₂均为以半双工模式运行的单天线节点，它们交替执行主动监听和干扰模拟全双工监视器的行为。在任何时隙内，M ₁发送一个干扰信号，使D和M ₂处的信号接收恶化 在下一个时隙中，M ₁监听从S 发送的信号，M ₂在前一个时隙中转发其接收到的信号以实现干扰。这样，在M ₁处接收到的干扰信号 自干扰消除后，可以完美地去除信号，并且以高可靠性联合解码两个连续时隙中来自S的信号，从而实现成功的监视。另一方面，由于干扰信号的注入，D处的检测性能大大降低，从而防止了信息从S泄漏到D处。根据窃听非中断概率，监视成功概率以及符号错误概率。理论分析和仿真结果表明，与文献中的同类解决方案相比，我们的设计具有优越性。