A realistic performance assessment of any wireless technology requires the use of a channel model that reflects its main characteristics. The independent and identically distributed Rayleigh fading channel model has been (and still is) the basis of most theoretical research on multiple antenna technologies in scattering environments. This letter shows that such a model is not physically appearing when using a reconfigurable intelligent surface (RIS) with rectangular geometry and provides an alternative physically feasible Rayleigh fading model that can be used as a baseline when evaluating RIS-aided communications. The model is used to revisit the basic RIS properties, e.g., the rank of spatial correlation matrices and channel hardening.

中文翻译：

---

可重构智能表面的瑞利衰落建模和信道硬化

任何无线技术的实际性能评估都需要使用反映其主要特性的信道模型。独立同分布的瑞利衰落信道模型已经（并且仍然）是散射环境中多天线技术的大多数理论研究的基础。这封信表明，当使用具有矩形几何形状的可重构智能表面 (RIS) 时，这种模型在物理上不会出现，并提供了一种替代的物理上可行的瑞利衰落模型，可用作评估 RIS 辅助通信时的基线。该模型用于重新审视基本的 RIS 属性，例如空间相关矩阵的等级和通道硬化。