A survey of intelligent reflecting surfaces: Performance analysis, extensions, potential challenges, and open research issues

The rapid advancements in wireless communication have underscored the need for innovative solutions to enhance network performance, spectral efficiency, and energy savings. Intelligent Reflecting Surface (IRS) technology has emerged as a transformative approach that passively reconfigures wireless propagation environments, offering significant improvements without active power consumption. This survey provides a comprehensive analysis of IRS technology, covering its architecture, operational principles, and integration into next-generation wireless networks. We examine key performance metrics in various application scenarios, demonstrating IRS's potential to improve coverage, signal quality, and energy efficiency, with up to 40% higher spectral efficiency and substantial energy savings over traditional networks. The survey also explores the integration of IRS with advanced multiple access techniques such as Non-Orthogonal Multiple Access (NOMA) and Terahertz (THz) communication, positioning IRS as a critical enabler in future 6G networks. This survey contributes by offering an in-depth review of IRS design principles and operational mechanisms, presenting a performance analysis in various scenarios that highlights IRS's ability to improve network efficiency, and identifying practical challenges and open research areas, such as the need for robust channel estimation methods, effective interference management in dense networks, and IRS solutions scalable for urban and rural deployments. Additionally, we discuss the future trajectory of IRS standardization and the regulatory frameworks essential for large-scale deployment. By summarizing advancements and identifying key research directions, this survey aims to serve as a valuable reference for researchers and practitioners seeking to advance IRS technology in future wireless networks.