AI 中文总结
本文针对RIS辅助的CRN领域缺乏全面综述的空白，系统梳理其基础、设计、研究方向与挑战，为该领域研究提供统一参考与发展路线图。
AI 中文摘要
可重构智能表面（RIS）能够实现可编程的无线传播环境，为认知无线电网络（CRN）提供了新机遇，可提升频谱利用率、增强频谱与能量效率，并在低信噪比条件下可靠运行。结合RIS与CRN的互补优势，RIS辅助的CRN（RCN）已成为未来6G无线系统的有前景架构。尽管其重要性日益凸显，但该快速发展领域缺乏全面综述。本文填补了这一空白，对RCN进行系统且全面的综述：首先介绍CRN与RIS的基础，包括动态频谱接入模型、频谱感知技术、RIS工作原理及RIS架构；随后研究RCN的设计，涵盖其系统架构、部署策略、信道估计、频谱接入机制、通信协议，以及RIS与CRN参数的联合优化；接着将现有文献分为六大研究方向：性能分析、资源分配与优化、安全RCN、有源RIS、同时发射与反射RIS，以及机器学习赋能的RCN；最后探讨关键研究挑战与未来方向，包括可扩展性、实际部署、与新兴6G技术的融合、与演进网络架构的共存、标准化，以及安全与隐私。本综述为研究人员与从业者提供统一参考，并为RCN的未来发展制定路线图。
英文摘要
Reconfigurable intelligent surfaces (RISs) enable programmable wireless propagation environments, offering new opportunities for cognitive radio networks (CRNs) to improve spectrum utilization, enhance spectral and energy efficiency, and operate reliably under low signal-to-noise ratio conditions. By combining the complementary strengths of RISs and CRNs, RIS-assisted CRNs (RCNs) have emerged as a promising architecture for future 6G wireless systems. Despite their growing importance, a comprehensive survey of this rapidly evolving field has been lacking. This paper fills this gap by providing a systematic and comprehensive review of RCNs. The paper first introduces the fundamentals of CRNs and RISs, including dynamic spectrum access models, spectrum sensing techniques, RIS operating principles, and RIS architectures. It then examines the design of RCNs, covering their system architectures, deployment strategies, channel estimation, spectrum access mechanisms, communication protocols, and the joint optimization of RIS and CRN parameters. Next, the existing literature is organized into six major research directions: performance analysis, resource allocation and optimization, secure RCNs, active RISs, simultaneously transmitting and reflecting RISs, and machine learning-enabled RCNs. Finally, the paper discusses key research challenges and future directions, including scalability, practical deployment, integration with emerging 6G technologies, coexistence with evolving network architectures, standardization, and security and privacy. This survey provides a unified reference for researchers and practitioners and establishes a roadmap for the future development of RCNs.
Comments30 pages, 17 figures, 9 tables, tutorial
