2024

Chen, Xinying; Chang, Zheng; Hämäläinen, Timo

Covert communication can hide confidential signals in environmental noise to avoid being detected and provide comprehensive security for wireless transmission. However, there still exists significant risks in the wireless transmission once being detected. In this paper, we propose a more secure covert scheme, where a multiple antennas transmitter assisted by a multi-antenna UAV jammer maximizes the covert secrecy rate under the scenarios of both correct and incorrect detection by a warden with both error detection probability and eavesdropping rate limitations satisfied. The transmitter and jammer adopt maximum ratio transmission (MRT) and zero-forcing to maximize the transmission rate and minimize the interference at the receiver, respectively. First, we analyze the monotonicity of error detection probability to determine the optimal power detection threshold and the corresponding largest error detection probability. Then, under this worst case, we jointly optimize the transmit and jamming power to maximize the covert secrecy rate while guaranteeing the covert and eavesdropping limits meet their respective requirements. Finally, simulation results are presented to prove the correctness of the theoretical conclusion and evaluate the effectiveness of our proposed scheme.