Optimizing Age of Information for Multi-Antenna Aided Covert Communications

The performance of wireless communication systems has been improved with the recent advances in array antenna technology. In this paper, we propose a scheme to improve the age of information (AoI) for covert communication with multi-antenna technique (MAT). Specifically, we first propose the transmitter structures and the corresponding beamforming methods for the considered model. Subsequently, the closed-form expressions of the Kullback-Leibler (KL) divergence is derived to serve as the quantitative measure of communication covertness under both schemes, based on which the average covert AoI (CAoI) is derived to jointly characterize the covertness and timeliness performance. Then, to minimize the average CAoI, the optimization problems of the blocklength and beamforming parameters are formulated and solved. Finally, the numerical results are provided to show that the proposed scheme indeed improve the covert communication performance in terms of the average CAoI.

I. Introduction

With the widespread interconnectivity in sixth-generation (6G) mobile communication [1], the Internet of Things (IoT) assumes a central role in diverse applications, including smart homes and industrial automation. However, the proliferating number of IoT devices inadvertently broadens the scope of potential entry points for threats, thereby elevating the risk of security breaches [2], [3]. Furthermore, while the interconnectivity of IoT networks enables seamless data exchange between devices, it also presents formidable challenges in ensuring data protection during transmission [4]. Covert communication [5], which aims to transmit information while preventing adversaries from detecting the presence of communication, has attracted significant attention in recent years [6]. Due to the unique ability of hiding communication behavior, covert communication offers superior security levels compared to traditional secure communication techniques [7]. The ground-breaking work [8] uncovered the square root limit of covert transmission over an additive white Gaussian noise (AWGN) channel, marking a notable milestone in the field of covert communication. Since then, remarkable progress has been achieved in the information theory of covert communication [9], prompting researchers to delve deeply into various aspects of this intriguing communication paradigm.