The spectrum efficiency (SE) and security of the secondary users (SUs) in the cognitive radio networks (CRNs) have become two main issues due to the limitation interference to the primary users (PUs) and the shared spectrum with the PUs. Intelligent reflecting surface (IRS) has been recently proposed as a revolutionary technique which can help to enhance the SE and physical layer security of wireless communications. This paper investigates the application of IRS in an underlay CRN, where a multi-antenna cognitive base station (CBS) utilizes spectrum assigned to the PU to communicate with a SU via IRS in the presence of multiple coordinated eavesdroppers (Eves). To achieve the trade-off between the secrecy rate (SR) and energy consumption, we investigate the secrecy energy efficiency (SEE) maximization problem by jointly designing the transmit beamforming at the CBS and the reflect beamforming at the IRS. To solve the non-convex problem with coupled variables, we propose an iterative alternating optimization algorithm to solve the sub-problems alternately, by utilizing an iterative penalty function based algorithm for sub-problem 1 and the difference of two-convex functions method for sub-problem 2. Furthermore, we provide a second-order-cone-programming (SOCP) approximation approach to reduce the computational complexity. Finally, the simulation results demonstrate that IRS can help significantly improve the SE and enhance the physical layer security in the CRNs. Moreover, the effectiveness and superiority of our proposed algorithm in achieving the trade-off between the SR and energy consumption are verified.
翻译:认知无线电网络(CRN)中第二用户的频谱效率(SE)和安全性(SUs)已成为两个主要问题,因为对初级用户(PU)和与PU的共享频谱的干扰有限。 智能反映表面(IRS)最近被提议为革命性技术,有助于增强SE和无线通信的物理层安全。 本文调查了IRS在CRN的底部应用IRS。 多连接认知基站(CBS)利用分配给PU的频谱通过IRS与SU进行交流,同时有多个协调的Eave监听器(Eves)。为了实现保密率(SR)与能源消耗之间的交换,我们通过联合设计CBS和无线通信物理层安全安全性安全性(SEEE)的传送波束和光谱。为了解决非连接变量造成的非连接问题,我们建议通过SULO-CRVS的交互交替混合优化算法来解决子问题,通过多协调的ISCRVSL(E-RV) 和SLOLLLOLLLLLLLLLO 提供我们S- sOL- ROL- ROL- RLUDLUDLLLLULLLLLLLLLLLLL 和S-S-S-SLULUDLLLLLLLLLE。