Fairness Aware Beamforming for Jamming Assisted Multi-User Covert Communications

This paper studies the beamforming design for jamming assisted multi-user covert communications under the surveillance of an eavesdropper. Different from existing work, the impact of multi-user interference as well as the tradeoff between the jamming and the confidential signal power allocation are taken into consideration. To degrade the eavesdropper's signal detection capability, the power of the jamming signal is often randomized, which introduces uncertainty to the achievable transmission rate. In light of this, we propose to carry out the beamforming design with the concept of quantile transmission rate (QTR) so that the expected covert transmission rate can be achieved with high probability. With QTR, the fairness aware multi-user beamforming design problem is formulated to maximize the minimum QTR among all legitimate users while ensuring the covertness constraints are satisfied. Given the nonconvexity of the constraints, we propose a successive convex approximation (SCA)-based iterative algorithm for effective solution finding. The validity of the obtained covert beamforming scheme is evaluated through various experiments.