Securing Intelligent Reflecting Surface (IRS)–Aided NOMA Networks in Covert Wireless Communication Using Jammer

In this paper, an intelligent reflecting surface (IRS)–assisted non-orthogonal multiple access (NOMA) network is proposed in a multi-user scenario where the transmitter communicates with its receiver covertly by helping a friendly jammer. In this network, an adversary detects the communication existence of the users in the frequency band while the jammer sends the jamming signals to the adversary to degrade its performance. In this case, the analytical expressions for the secrecy outage probability (SOP), false alarm probability, and the missed detection probability at adversary are obtained. Rayleigh fading channel is assumed as the channel model while the covert communication performance is improved. For this purpose, the total effective rates are maximized by optimization of the transmission power, power allocation to multiple users, IRS reflection matrix, and also transmission probability adjustment with constraints on the detection performance and SOP. The problem is non-convex; therefore, we present the genetic algorithm (GA) method to find the suboptimal solution for the problem with lower complexity. Numerical results show the performance improvement of the proposed algorithm in comparison to the benchmark algorithms.