Advancing wireless system secrecy performance via aerial intelligent reflecting surfaces amid hardware impairments

This article proposes to utilize an unmanned aerial vehicle mounted reconfigurable intelligent surface (shortened as UAV/RIS) for enhancing the secrecy capacity of wireless systems with an eavesdropper. Unlike previous studies, a legitimate user in this article receives signals via both transmitter-user link and reflected UAV/RIS links. Additionally, the article takes into account the impact of hardware impairments (HI) to provide a realistic model of practical scenarios. The mathematical expression of average secrecy capacity (ASC) and its asymptotic expression of the proposed UAV/RIS-HI systems with eavesdropper are derived over realistic Nakagami-m channels that fully reflect the fifth- and beyond-generation (5G-B5G) channel features. These expressions provide valuable insights into the effectiveness of utilizing the UAV/RIS in enhancing the ASC of the proposed systems. Numerical results reveal that the integration of UAV/RIS in the proposed systems with HI and eavesdropper significantly boosts the ASC. This enhancement is especially notable when compared to classical systems with HI and without UAV/RIS. Moreover, the proposed systems can achieve the highest ASC earlier than the classical counterparts, demonstrating that exploiting UAV/RIS is an effective means of reducing the power consumption of wireless systems while improving security. Furthermore, an in-depth analysis of the impact of HI on the ASC of the proposed UAV/RIS-HI systems is also provided, shedding light on the challenges associated with this problem. Furthermore, the behavior of the proposed UAV/RIS-HI systems is explored by varying various system parameters, including the level of HI, the number of reflecting elements (REs) in the UAV/RIS, frequency considerations related to WiFi networks, the altitude of the UAV/RIS, and available bandwidth. Drawing from these insights, several recommendations for enhancing the ASC of the proposed UAV/RIS-HI systems with eavesdropper are proposed.