Adaptive Wireless Covert Communication with Full/Half-Duplex Transceiver using Artificial Noise

Wireless covert communication has recently attracted attention as a suitable solution for hiding the presence of communication from a Warden (Willie). The transmission's concealment level depends on Willie's ambiguity in detecting the sender's (Alice) transmission. Artificial noise (AN) has emerged as a prominent technique to increase the ambiguity of the transmission. Still, excessive AN power can adversely affect the communication between Alice and the intended recipient (Bob). In this paper, we propose an adaptive method to control the impact of AN power on the legitimate user, Bob. We examine the adaptation techniques for two types of transceivers: full-duplex (FD) and half-duplex (HD). Bob regulates AN power in FD transceivers according to Alice's transmission power. Conversely, in HD transceivers, the allocation of transmission slots between Alice and AN is managed. We formulate an optimization problem and mathematically solve it for scenarios involving Additive White Gaussian Noise (AWGN) with large-scale fading channels. Simulation results validate the analytical findings and demonstrate the effectiveness of our proposed adaptive method.