A Method for Calibration of RIS Array Element Errors Based on Dynamic Reconstruction of Time-Domain Electromagnetic Response

The performance of Reconfigurable Intelligent Surfaces (RIS) as an innovative technology for enhanced communication is constrained by errors in their array elements. The communication system assisted by RIS is characterized by its large array number and the use of a single receiving channel. To achieve the multichannel transmission required for RIS calibration, existing methods require the use of auxiliary calibration sources or receivers equivalent in number to the RIS elements. This makes conventional methods for calibrating positional inaccuracies of array elements unsuitable. In addition, the effect of reflection coefficient inaccuracies on performance is equally significant. This paper proposes a method for jointly calibrating the errors of RIS array elements. The method is based on dynamically reconstructing the electromagnetic response in the time domain to address the problem. This method uses the programmability and flexibility of RIS to virtualize a physical single-channel receiving system into a logical multichannel signal processing system. At the receiver end, the signal amplitude and phase information equivalent to that of a conventional multi-channel array are recovered. This facilitates the estimation of fixed errors in each element of the RIS. Simulation outcomes validate the enhanced performance of our proposed algorithm.