Then the achievability of covert communication depends entirely on the channel quality difference between the receiver and Eve, which is difficult for communicators to control. Suppose that there is no secret information shared between the transmitter and the receiver. We assume that Eve is not aware of the exact codebook and time-frequency band of the target system. The second type is a follower jammer, which detects an ongoing communication signal and then radiates a jamming signal to interfere with this ongoing signal. The first type is a blind jammer, which radiates a partial-band or pulse jamming signal without knowing when or where a target communication signal exists. The proposed system transmits information messages on a coded Gaussian signal through a wireless channel that is attacked by an eavesdropper, called Eve in this paper, and a jammer. In this paper, we consider wireless communications under a jammer and eavesdropper scenario, for example, the electronic warfare scenario depicted in Figure 1. Thus, analog coding can be applied to anti-jamming communication. Studies motivated by analog coding and many other CS-based anti-jamming approaches have exploited the sparse characteristic of jamming in both the time-frequency and spatial domains. Candes and Tao proposed a sparse error-correction method for an arbitrary generator matrix, which is a polynomial–time linear programming method unified within a compressive sensing (CS) recovery framework. Researchers have studied a generalization of this coding scheme: a complex-field coding using orthogonal frequency-division multiplexing (OFDM). ![]() The code can correct sparse errors (e.g., narrowband jamming). The idea of real-valued channel coding has been used, and is known as analog coding. Furthermore, the legitimate receiver can use the error-correction property of the coding scheme. If the modulated symbols follow a Gaussian distribution, it is difficult for the eavesdropper to distinguish whether there is a communication signal or not without an exact codebook. The coded modulation method using Gaussian-distributed code can be a complement to the SS scheme.
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