一個均勻線性陣列的可重構智能表面 (RIS) 服務覆蓋範圍的近似分析

Abstract

可重構智能表面簡稱RIS，是一種被動反射器，具有多個可調節相位的元件。它可以通過建設性干擾增強信號強度，並解決高頻的高路徑損耗和阻塞問題。近年來，RIS被研究在信息安全、定位、物聯網(IoT)等方面。其中技術討論包括不同模型假設的合理性、RIS的相位選擇、RIS的服務覆蓋範圍等。RIS的服務覆蓋範圍是衡量RIS性能的一種方式。均勻線性陣列(ULA)是沿直線等距排列的傳感器元件的集合。它可以讓我們在三維空間中進行降維分析。本論文旨在探討一個ULA RIS的服務覆蓋範圍。我們對RIS服務覆蓋範圍的定義是在基站（BS）和RIS之間，使用者（UE）接收到的信噪比（SNR）高於閾值的區域。本論文的貢獻在於以下幾點。首先，我們推導RIS服務覆蓋範圍的計算公式。假設使用者接收到的功率在設定的環境中最大，我們使用信噪比的閾值來推導覆蓋公式。其次，我們對RIS服務範圍做近似分析。為了簡化公式，我們使用二項式展開和勒壤得多項式近似覆蓋範圍的公式。第三，根據數值模擬，我們知道了各種參數與RIS服務覆蓋範圍之間的關係。它可以使分析結果更具參考價值。

Reconfigurable Intelligent Surface (RIS) is a passive reflector with multiple components that can adjust the phase. It can enhance signal strength through constructive interference and tackle high path loss and blocking problems in high frequencies. In recent years, RIS has been studied in information security, positioning, Internet of Things (IoT), etc. The technical discussions include the rationality of different model assumptions, the phase selection of RIS, the service coverage of RIS, etc. The service coverage of RIS is a way of judging the performance of RIS. A Uniform Linear Array (ULA) is a collection of sensor elements equally spaced along a straight line. It allows us to reduce the dimensional analysis in three-dimensional space. This thesis aims to explore the service coverage of a ULA RIS. Our definition of the RIS service coverage is the area between the base station (BS) and the RIS, where the signal-to-noise ratio (SNR) received by the user (UE) is higher than the threshold. The contribution of this thesis lies in the following. First, we derive the calculation formula of RIS service coverage. Assuming that the power received by the user is maximum in the set environment, we use the threshold of SNR to derive the coverage formula. Second, we make an approximate analysis of RIS service coverage. To simplify the formula, we approximate the coverage formula using binomial expansion and Legendre polynomials. Third, according to the numerical simulation, we know the relationship between various parameters and RIS service coverage. It can make the analysis results more valuable for reference.