Physical Layer Security in Cognitive Radio Networks for IoT Using UAV With Reconfigurable Intelligent Surfaces

In this paper, the secrecy performance of a cognitive radio networks (CRN) for Internet of Things (IoT) in the presence of an eavesdropper (EAV) is investigated. In particular, a primary transmitter (PT) communicates with multiple primary IoT device (ID) receivers (i.e., PRs) at the licensed frequency. Meanwhile a secondary transmitter (ST) uses the same licensed frequency of the primary network to send the confidential signal to an unmanned aerial vehicle (UAV) that is equipped with the reconfiguration intelligent surfaces (RIS) (called UAV-RIS) as a relay. The UAV-RIS then forwards this confidential signal to multiple secondary ID receivers (i.e., SRs). Furthermore, an EAV is located near the multiple SRs and can eavesdrop the confidential signal from the UAV-RIS. Accordingly, we propose the ST’s transmit power policy to not cause harmful interference to the primary network. In addition, the physical layer security (PLS) in terms of the secrecy outage probability (SOP) of the considered CRN is analyzed. The numerical results show that the secrecy performance of the secondary network is improved as the numbers of the RIS cells increase.