AoA Sensing Enabled Reconfigurable Intelligent Surface

This study developed an Angle of Arrival (AoA) sensor integrated with a reconfigurable intelligent surface (RIS) to enable user tracking. The system employs a six-port network to detect angles within a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\pm 30^{\circ}$</tex> range, achieving a maximum angle error of 3° and an RMSE of 1.3°, with a sensing time of less than 8 msec. By integrated AoA sensor with a 1600 -unit reconfigurable reflectarray, communication quality tests were conducted using 256-QAM modulated signal. Results demonstrated the system's ability to dynamically adjust the RIS phase distributions in real time as the user position changed. This rapid adjustment effectively restored communication quality, maintaining an error vector magnitude (EVM) below 3%. This work validates the potential of the proposed system for 6 G applications.