One of the first topics covered in this podcast was reconfigurable intelligent surfaces (RIS). Five years later, Erik G. Larsson and Emil Björnson return to this topic to reflect on what has happened since then. The conversation covers how these surfaces can improve wave propagation between transmitters and receivers, and identifies the most convincing practical use cases. Core challenges overcome in recent years are discussed, and Emil describes the RIS used in his lab and the lessons learned from his measurements. They also go through new forms of RIS, known as Beyond-Diagonal RIS, STAR-RIS, and Stacked Intelligent Metasurfaces. To learn more, you can read the paper “Reconfigurable Intelligent Surfaces in Upper Mid-Band 6G Networks: Gain or Pain?” (https://doi.org/10.1109/MWC.2025.3616979). Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/
