Intelligent Reconfigurable Surface-Assisted Symbiotic Radio Systems: Architecture, Applications and Challenges

The emergence of the sixth generation(6G) technology has catalyzed the evolution of the Internet of Things (IoT), fundamentally reshaping modern communications and daily life. Among the innovative technologies addressing IoT challenges, symbiotic radio (SR) and intelligent reconfigurable surfaces (IRS) have demonstrated remarkable potential. The SR technology revolutionizes IoT operations through its spectrum-sharing capabilities and enhanced connectivity mechanisms. By facilitating dynamically cooperative mechanism within shared frequency bands, SR significantly augments IRS functionality. Concurrently, IRS technology enhances both IoT and SR system performance through sophisticated signal manipulation, expanded coverage capabilities, and interference mitigation in high-density network environments. This synergy between SR and IRS not only improves connectivity but also reduces the need for traditional network infrastructure, making IoT operations more sustainable and cost-effective. This article systematically analyzes IRS-assisted SR systems, encompassing state-of-the-art developments, fundamental principles, deployment scenarios, and architectural frameworks. Furthermore, we examine critical technical challenges and delineate promising future research directions in this domain.