Optimal Transmission Probabilities of Information and Artificial Noise in Covert Communications

Abstract

This letter studies a wireless covert communication system, where a jammer generating intermittent artificial noise (AN) is employed to confuse the warden. The transmission probabilities of information and AN are jointly optimized to maximize the communication covertness under a throughput requirement. We first analyse the detection performance of the warden and the throughput of the system, based on which we formulate the optimization problem. Then, we simplify this two-dimensional nonconvex problem to a one-dimensional problem and obtain the closed-form optimal solutions in special cases. The results illustrate that the optimal transmission probabilities of information and AN are 0.5 and 1, respectively, when the throughput requirement is less than a threshold. However, 0.5 and 1 are not optimal when the throughput requirement exceeds the aforementioned threshold, which has not been reported yet.