Zero-forcing Beamforming for Jamming Aided Covert Communication in MIMO Systems

Abstract

This paper investigates covert wireless communication in a multi-input multi-output (MIMO) system, where a multi-antenna transmitter transmits covert signal to a multi-antenna receiver with the assistance of a multi-antenna jammer employing zero-forcing (ZF) beamforming to avoid detection by a warden equipped with single antenna. For the given scenario, we first provide theoretical modeling for the minimum detection error probability at warden and covert rate from transmitter to receiver. We then explore the optimal beamformer design of the jammer to maximize the covert rate, subjecting to the constraints of covertness, upper bounds of transmitter and jammer transmit power, and beamformer on jammer. We further devise an iterative algorithm to determine the related optimal precoding matrix for covert rate maximization. Finally, we provide extensive numerical results to illustrate the impact of system parameters on covert performance.