Abstract

The integration of unmanned aerial vehicle (UAV) networks and device-to-device (D2D) communications is expected to provide ubiquitous connectivity and high-speed rates for sensitive information transmission in future wireless networks. However, the traditional cryptography and physical layer security techniques still cannot prevent adversaries from knowing the existence of information transmission such that they further launch attacks on transmitters and receivers. Covert communication can offer an even stronger level of security via hiding the information transmission process of wireless networks. In this article, we first integrate D2D communications into UAV networks, and then investigate the fundamental issues of mode selection and cooperative jamming for covert communication in such networks, aiming to provide a powerful security solution to support widespread securi-ty-sensitive applications of such networks. To this end, we propose two promising D2D underlaid UAV network architectures, whereby each UAV acts as either a flying BS or an aerial UE. Then, we propose a covert communication strategy by combining mode selection and cooperative jamming, where mode selection allows each user equipment to adaptively switch between half-du-plex and full-duplex communication modes, and cooperative jamming means that idle D2D pairs inject interference to confuse adversaries. The goal of the proposed strategy is to enhance covert capacity performance (i.e., the maximum channel rate) while maintaining a high detection error probability at adversaries in the promising network architectures. Numerical results are presented to evaluate our strategy of mode selection and cooperative jamming, and to illustrate performance gains in terms of covert capacity and detection error probability in these two network architectures. Finally, a vision is discussed for our future research in D2D underlaid UAV networks.