Covert Non-Orthogonal Multiple Access Vehicular Communications with Friendly Jamming

Abstract

This paper considers covert communications in non-orthogonal multiple access (NOMA)-based vehicular networks. In the vehicular networks, the source vehicle aims to hide two covert mission instructions to the executive vehicle simultaneously with NOMA technique, which is monitored by a malicious monitor with a radiometer. For the covertness of the communications, we proposed a friendly jamming aided covert transmissions strategy. Specifically, an amiable jammer emits the jamming signals to confuse the monitor with the random power. Meanwhile, beamforming is performed to protect the legitimate communications from the jamming signals. Follow the model, we characterize the minimal detection error probability (MDEP) of the monitor, based on which the optimal detection threshold of its radiometer is acquired. Furthermore, an effective covert rate (ECR) maximization problem is formulated subject to the average MDEP constraint and interrupt constraint, and the optimal power parameters are acquired analytically. Numerical results are provided to validate the superiority of the proposed strategy.