RIS with Practical Reflection Coefficients: Modeling and Experimental Measurements

In this paper, we consider reconfigurable intelligent surfaces (RIS)-aided wireless communication systems, where the reflection coefficients suffer from the realistic limitations of non-uniform amplitudes and insufficient phase shifting capabilities. We introduce a reflection coefficient model for RIS based on measurements, accounting for these practical factors. We then propose a group-based query algorithm that takes the imperfect coefficients into consideration while calculating the reflection co-efficients. We analyze the performance of the proposed algorithm and derive a closed-form expression of the received power. The performance gains of our proposed algorithm are confirmed in simulations. Finally, we validate the proposed theoretical results by experiments with our fabricated RIS prototype system. The simulation and measurement results match well with the theoretical analysis.