Statistical Characterization of SNR in RIS-Aided Wireless Communication Systems
Mohammad Reza Ghavidel Aghdam, Mohammed Elamassie, Murat Uysal · 2024
Reconfigurable intelligent surfaces (RISs) can significantly improve overall communication quality by mitigating the adverse effects of multipath fading, reducing interference, and extending coverage areas. Most existing works on RIS focus on far-field scenarios and large-scale RIS configurations, where the central limit theorem (CLT) is often used to approximate the distribution of the cascaded channels. However, such an approximation may not accurately reflect the performance of RIS in near-field conditions or when the number of reflecting elements is small. In this paper, we provide a statistical characterization of signal-to-noise ratio (SNR) in RIS-assisted wireless systems in near-field conditions with a small number of RIS elements. Our results demonstrate that Gamma distribution accurately depicts instantaneous SNR distribution. The proposed model provides an accurate tool for understanding and predicting the performance of RIS systems under diverse operational conditions.