Environment-Adaptive Reconfigurable Intelligent Surface for Dynamic Channel Conditions

This article presents an environment-adaptive reconfigurable intelligent surface (RIS) that can optimize its phase distribution in response to varying wireless channel conditions. It employs varactor diodes for controlling the reflection phase and a portion of the received electromagnetic wave (signal) is employed to obtain radio frequency (RF) phase information using via. The mutual coupling between each unit cell is suppressed by fencing the via walls for accurate sensing. The phase information is converted to the visual image to be used in convolutional neural network (CNN). CNN is used to determine the position of the receiver device (RX), and a micro controller unit (MCU) adjusts the phase distribution based on this position through a feedback loop. That the proposed RIS structure and the feedback loop can improve the wireless link budget for randomly configured scenarios at 28 GHz has been experimentally validated, and it can be applied to other frequencies. Three scenarios are examined in-depth by creating a miniature diorama to emulate real-world channel conditions. The sensing system demonstrated over 99 percent accuracy in determining the receiver position while enhancing wireless reception. This RIS can direct the reflected beam to different receiver positions in dynamic channel conditions, offering potential solutions for practical deployment challenges in future wireless applications.