Optimization of Secrecy Rate Based on Power Control and Beamforming Aided by RIS in Hybrid Cognitive Radio Networks

• Shuqi Liu,
• Jiawei Ji,
• Yulong Shang,
• Cuimei Cui,
• Shuyan Xiao,
• Lei Zhang,
• Jianjie Tian,

Vol. 19, No. 10, October 31, 2025
10.3837/tiis.2025.10.018, Download Paper (Free):

• secrecy rate
• Reconfigurable intelligent surface
• hybrid cognitive radio network
• Power control
• beamforming

Abstract

This paper investigates the maximization problem of secrecy rate in hybrid cognitive radio networks (HCRNs) with the assistance of a reconfigurable intelligent surface (RIS). The secure communication method is studied, which takes into account two types of spectrum access modes, i.e., interweave and underlay, the characteristics of RIS, the threat of eavesdropping user, and the power control strategy in cognitive radio networks. Using convex optimization theory, the secret rates of cognitive networks are maximized in interweave mode and underlay mode, respectively, through a joint optimization of both the transmit power of secondary user and the beamforming of RIS. On this foundation, a method of jointly optimizing secret rate is proposed in the hybrid spectrum access mode. The impact of network parameters on the confidential rate is analyzed in depth, and the security of cognitive networks is discussed. The theoretical analysis in this paper aims to maximize the confidentiality rate. Then the optimal RIS phase shift matrix and secondary user transmission power are obtained through convex optimization via semidefinite programming (SDP), thereby achieving the improvement of the confidentiality rate. The experimental simulation has shown that the proposed method can significantly improve the security rate of HCRNs, which means that the security of HCRNs has been enhanced. With the aid of RIS, the secrecy rate is substantially improved compared to scenarios without RIS. Further, the secrecy rate in HCRNs is improved even more, which demonstrates the validity of the proposed method.

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