STAR-RIS-assisted key generation method in quasi-static environment

• Published in: EURASIP journal on wireless communications and networking 2024-07, Vol.2024 (1), p.55-17, Article 55
• Main Authors: Ma, Yang, Chen, Liquan, Lu, Tianyu, Song, Yufan, Cao, Kailin
• Format: Article
• Language: English
• Subjects: Communications Engineering; Correlation coefficients; Engineering; Information Systems Applications (incl.Internet); Information theory; Key capacity; Networks; Physical layer key generation; Protocol; Reconfigurable intelligent surface; Reconfigurable intelligent surfaces; Signal reflection; Signal,Image and Speech Processing; Switching; Wireless secure communication
• ISSN: 1687-1499; 1687-1472; 1687-1499
• DOI: 10.1186/s13638-024-02388-y

In this paper, we introduce a new method to solve the low-entropy problem in a quasi-static environment. We utilize a simultaneous transmission and reflection reconfigurable intelligent surface (STAR-RIS) that transmits and reflects incoming signals to users located on different sides of the surface. Specifically, we design the flow of multi-user channel probing when STAR-RIS is assisted, analyze and derive the analytical expression of the secret key capacity (SKC) of STAR-RIS-assisted system from the perspective of information theory, and finally analyze how to maximize the SKC and sum of all users under three different working protocols of STAR-RIS. The simulation results show that: (1) STAR-RIS can achieve better SKC performance than the conventional reflection/transmission RIS; and (2) the SKC is determined by the number of STAR-RIS elements, correlation coefficient, pilot length and RIS-reflected channel quality, and the time switching protocol can obtain higher SKC than the energy splitting protocol and mode switching protocol.