Multi-user beamforming with a reconfigurable intelligent surface using stereo camera images

This paper proposes and experimentally evaluates, a reconfigurable intelligent surface (RIS) control system for multiple users using stereo camera images. The aim is to enable fast and fair received signal strength (RSS) beamforming for multiple users. In the proposed system, a stereo camera is mounted on top of the RIS. Human bodies are recognized from the obtained images. Subsequently, the beam directions and the phase of the RIS are calculated for the estimated positions. The stereo camera-based scheme enables fast beamforming because channel state information estimation is omitted. Moreover, identical RSS beamforming is enabled by calculating the weighted sums of the RIS phases for multiple users utilizing distance and angle information of users from the RIS obtained using the stereo camera. Experiments are conducted in an anechoic chamber using RIS operating at 28 GHz. The efficacy of the RIS control system using stereo camera images and its ability to increase the RSS fairly for multiple users is validated via simulations and experiments. In this study, a reconfigurable intelligent surface control system utilizing stereo camera images is introduced for efficient beamforming to multiple users. By recognizing human positions from the camera images, the system bypasses the need for channel state information estimation, allowing rapid and equitable signal enhancement. The system's performance is validated at 28 GHz through simulations and experiments in an anechoic chamber.image