Hardware Limitations and Optimization Approach in 1-Bit RIS Design at 28 GHz

TL;DR

This paper presents a 1-bit RIS prototype at 28 GHz, analyzing hardware limitations and phase quantization effects, and introduces a genetic algorithm-based optimization to improve reflection performance under practical constraints.

Contribution

It develops a real 1-bit RIS prototype at 28 GHz and proposes an optimization method to mitigate hardware-induced phase errors, advancing practical RIS implementation.

Findings

Hardware limitations cause specular reflections and phase errors.

Genetic algorithm optimization improves reflection gain.

Experimental validation confirms enhanced RIS performance.

Abstract

Reconfigurable intelligent surfaces (RIS) have emerged as a transformative technology for electromagnetic (EM) wave manipulation, offering unprecedented control over wave reflections compared to traditional metallic reflectors. By utilizing an array of tunable elements, RIS can steer and shape electromagnetic waves to enhance signal quality in wireless communication and radar systems. However, practical implementations face significant challenges due to hardware limitations and phase quantization errors. In this work, a 1-bit RIS prototype operating at 28 GHz is developed to experimentally evaluate the impact of hardware constraints on RIS performance. Unlike conventional studies that model RIS as an ideal phase-shift matrix, this study accounts for physical parameters that influence the actual reflection pattern. In particular, the presence of specular reflection due to hardware limitations is investigated. Additionally, the effects of phase quantization errors, which stem from the discrete nature of RIS elements, are analyzed, and a genetic algorithm (GA)-based optimization is introduced to mitigate these errors. The proposed optimization strategy effectively reduces gain degradation at the desired angle caused by 1-bit quantization, enhancing the overall performance of RIS. The effectiveness of the approach is validated through measurements, underscoring the importance of advanced phase control techniques in improving the functionality of RIS.