IRS Calibration for Geometric Errors in Real-World Beamforming: Conceptualization and Experimental Validation

Intelligent reflecting surfaces (IRSs) have emerged as a promising technology for enhancing wireless communications by dynamically shaping the propagation environment using controllable passive elements. However, installation angle and position errors must be addressed for real-world IRS implementation, as neglecting these physical misalignments significantly degrades beamforming accuracy and communication quality. This study addresses this challenge by introducing the concept of IRS calibration. Calibration is the process of estimating the incident and reflection angle offsets and correcting them via phase control on the IRS side to recover optimal beamforming. Key design issues are identified by performing calibration under real-world constraints. It is proposed that decoupled angular offsets can be uniquely identified using power measurements at two receiver points. The effectiveness of the proposed method is verified via experiments in the 28 GHz band using actual IRS hardware. The experimental results confirm that the impact of angular errors is successfully reduced across various error scales and reflection directions. The findings of this study highlight the importance and feasibility of calibration as a basis for real-world IRS deployment.