Intelligent Reflecting Surface-Assisted Cognitive Radio Networks: Recent Trends, Usages, Challenges, and Future Directions

Intelligent Reflective Surface (IRS) revolutionizes wireless network design by enabling precise control over signal propagation, which significantly enhances network performance. IRS optimizes wireless links by intelligently adjusting reflected signal properties, boosting power for legitimate users while curbing interference and enhancing security against eavesdropping. On the other hand, cognitive radio networks (CRNs) are known to be efficient solutions when it comes to dynamic spectrum usage. To perform this task, the cognitive radio users are required to continuously sense the neighboring licensed and unlicensed users signals, thus, enhanced signal quality becomes an important concern in these networks. Given the promising potential of IRS, this paper provides a comprehensive review of its application in CRNs. We begin by discussing how IRS can be integrated into CRNs, followed by a brief survey of its various usages within this context. Additionally, we outline the main challenges and open issues associated with the effective deployment of IRS in CRNs and suggest future research directions.