多重路徑傳播通道下信號到達方向估測演算法則之探討及效能分析

Abstract

多重路徑傳播通道下信號到達方向估測演算法則之探討及效能分析 研 究 生：蘇啟仁 指導教授：彭松村 博士 國 立 交 通 大 學 電 信 工 程 學 系 摘 要 智慧型天線系統是在使用者對基地台的上鏈通訊中採用一組特定排列方式的陣列天線，利用空間分隔多工進階存取（SDMA）的方式，將每個使用者的空間特徵或方位分辨出來，藉此而達到用戶容量的增加、通 訊品質的提昇及多重路徑效應的消除。本文將探討DFT、MVDR、MUSIC和ESPRIT等四種信號到達方向估測演算法則之上鏈模擬與效能評估，並且以假設的信號到達方向和利用應用軟體所建立的模擬環境，探討無線通訊上常見的幾種參數（如：天線高度、多重路徑個數…）對於上鏈信號到達方向演算法則的影響。本文也指出ESPRIT使用於實際環境中的限制，提供應用陣列天線演算法則於實際環境中之有效參考。論文最後提出Subspace smoothing和Two-dimensional ESPRIT兩種方式，前者用來有效減低信號到達路徑間的相關性，後者用來改善演算法則可解析的信號到達方向個數受天線陣列個數所限制的缺點，並且模擬比較傳統方法和Subspace smoothing以及Two-dimensional ESPRIT的結果。 關鍵詞：智慧型天線系統；陣列信號處理；信號到達方向演算法則

Investigation and Performance Evaluations of Directional Finding Algorithms in Multi-path Propagation Channels Student : Chi-Jen Su Advisor : Dr. Song-Tsuen Peng Institute of Communication Engineering National Chiao Tung University Hsinchu, Taiwan Abstract By utilizing a phased array antenna composed of multiple antenna elements and applying direction finding algorithms at the base station using spatial-division-multiple-access (SDMA) scheme in an uplink communication path, one can combat multi-path fading, reduce interference, increase power efficiency, obtain diversity gain, and improve system performance. In this thesis, direction finding algorithms, such as DFT、MVDR、MUSIC、and ESPRIT, are simulated and evaluated using assumed angles of arrival and array responses derived from ray tracing model. Besides, we point out the limitations of applying ESPRIT algorithm in real mobile user scenarios and provide recommendations for applying array signal processing algorithms in real multi-path user environments. In the thesis two methods, subspace smoothing and two-dimensional ESPRIT are proposed for improving the performance of ESPRIT algorithm. The former one is used to effectively eliminate the correlations among multi-path signals. The latter one is used to improve the defeat that the number of estimated angle arrivals by direction finding algorithm are limited by the number of antenna elements. Moreover, simulation results and comparison between proposed methods and traditional ESPRIT algorithm are presented in this thesis. Keywords：Smart antenna system; Array signal processing; Direction finding algorithm