Reconfigurable Intelligent Surfaces

Reconfigurable intelligent surfaces (RIS) have gained significant interest in recent years in academia and the wireless industry due to their wide range of potential benefits for modern millimeter-wave systems as well as for traditional sub-6 GHz wireless communications systems. These benefits range from significant radio coverage improvements to reduction of the energy consumption of the radio subsystem. RIS surfaces provide a potential solution for challenging coverage issues by supporting configurable reflection/ refraction/scattering patterns in the millimeter-wave range in particular. Thus, impinging radio signals, e.g. from base stations, can be supported on their way to the mobile device and vice versa. Furthermore, this technology can be used to enhance the multipath radio propagation characteristics, leading to improved conditions for spatial multiplexing applications. Consequently, RISs can help to increase the overall throughput of the network. RISs can even be used to create intentional radio dead zones, e.g. to minimize interference or to prevent eavesdropping by suspicious user equipment. Currently, there are many potential applications under discussion in connection with the deployment of RIS technology in radio networks.