The idea of using a Reconfigurable Intelligent Surface (RIS) consisting of a large array of passive scattering elements to assist wireless communication systems has recently attracted much attention from academia and industry. A central issue with RIS is how much power they can effectively convey to the target radio nodes. Regarding this question, several power level models exist in the literature but few have been validated through experiments. In this paper, we propose a radar cross section-based received power model for an RIS-aided wireless communication system that is rooted in the physical properties of RIS. Our proposed model follows the intuition that the received power is related to the distances from the transmitter/receiver to the RIS, the angles in the TX-RIS-RX triangle, the effective area of each element, and the reflection coefficient of each element. To the best of our knowledge, this paper is the first to model the angle-dependent phase shift of the reflection coefficient, which is typically ignored in existing literature. We further measure the received power with our experimental platform in different scenarios to validate our model. The measurement results show that our model is appropriate both in near field and far field and can characterize the impact of angles well.
翻译:使用一个可重新配置的智能表面(RIS)的想法,由大量被动散射元素组成,协助无线通信系统,最近引起了学术界和工业界的极大关注。与RIS的一个中心问题是它们能向目标无线电节点有效传递多少权力。关于这个问题,文献中存在几个权力级模型,但通过实验验证的却很少。在本文中,我们为一个植根于RIS物理特性的RIS辅助性无线通信系统提出了一个雷达跨区级接收动力模型。我们提议的模型所根据的直觉,即接收能量与从发报机/接收器到IRS的距离、TX-RIS-RX三角的角、每个要素的有效区域以及每个要素的反射系数有关。据我们所知,本文是第一个模拟反射系数的以角度为依次的阶段变化模型,而现有文献中通常忽视了这种变化。我们用实验平台在不同的情景下进一步测量获得的能量,以验证我们的模型。测量结果显示,我们的模型在近场和远场都是适当的,可以描述角度的影响。