Covert Communications in Active Reconfigurable Intelligent Surface Based Symbiotic Radio Systems

• Published in: IEEE transactions on vehicular technology Vol. 74; no. 3; pp. 5164 - 5169
• Main Authors: Huang, Ke-Wen, Shi, Shaoqin, Wang, Hui-Ming, Yang, Liang
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.03.2025; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Communication system security; Constraints; Covert communications; Decoding; Finite element analysis; Iterative methods; Radio; Receivers; reconfigurable intelligent surface; Reconfigurable intelligent surfaces; Reflection; Signal to noise ratio; Symbiosis; symbiotic radio; Symbols; Vectors; wireless security
• ISSN: 0018-9545; 1939-9359
• DOI: 10.1109/TVT.2024.3492196

We study a covert communications problem in an active reconfigurable intelligent surface (ARIS) based symbiotic radio system. In the considered system, the ARIS helps to improve the communications performance between a pair of primary transceivers, and in the meantime, it covertly communicates with a secondary receiver via reflection modulation. To achieve this, a reflection element-grouping scheme is adopted at the side of the ARIS. Subject to a quality-of-service constraint on the primary link and a covertness constraint on the secondary link, the reflection coefficients of the ARIS are designed to maximize the signal-to-noise ratio of the secondary receiver. For such a non-convex problem, an efficient iterative method is proposed to find a sub-optimal solution. Numerical experiments are conducted to evaluate the achievable covert communications performance.