In this paper, a reconfigurable intelligent surface (RIS)-aided underlay cognitive radio network is investigated. An RIS is utilized to improve the secondary network (SN) reliability and robustness while simultaneously increasing the physical layer security of the primary network (PN). Toward this end, closedform expressions for the SN outage probability, PN secrecy outage probability, and PN probability of non-zero secrecy capacity are derived. To increase the eavesdropping signals of the PN, the eavesdropper uses two combining techniques, namely maximal ratio combining and selection combining. Furthermore, the advantages of the proposed system model are verified through numerical and simulation results.

中文翻译：

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底层认知无线电网络中 RIS 辅助的物理层安全改进

在本文中，研究了可重构智能表面（RIS）辅助的底层认知无线电网络。RIS 用于提高辅助网络 (SN) 的可靠性和鲁棒性，同时提高主网络 (PN) 的物理层安全性。为此，导出了SN中断概率、PN保密中断概率和非零保密容量的PN概率的闭式表达式。为了增加PN的窃听信号，窃听者采用两种组合技术，即最大比组合和选择组合。此外，通过数值和仿真结果验证了所提出系统模型的优势。