Design Considerations and Propagation Properties Using an SDN-Controlled RIS for Wireless Backhauling

With the rising need for robustness and safety in fifth-generation (5G)/sixth-generation (6G) backhaul communication between radio units (RUs), the significance of reconfigurable intelligent surfaces (RISs) becomes crucial. While several studies have addressed RIS application scenarios between RU and user equipment (UE), there is currently a lack of published research on implementing RIS in a wireless backhaul system, strategically managed by a software defined networking (SDN). This article investigates the factors that influence RIS realization and application, such as gain, far-field, losses, and communication metrics. Moreover, application and scaled-down demo scenarios are proposed: $ {\mathrm {2}} \times \, {\mathrm {2~\text {m}}}$ for real-life backhaul applications and $ {\mathrm {10}} \times \, {\mathrm {10~\text {c}\text {m} }}$ for the demo case operating at 28 GHz. The article also explores application scenarios, including enhancing physical layer security, improving system resilience, and temporarily increasing capacity by deploying RIS in a wireless backhaul system. In addition, the study explores the dynamic SDN aspects of controlling the entire wireless backhaul system, offering a comprehensive perspective on RIS integration. These findings underscore the importance of RIS in addressing key challenges in wireless communications.