李枝宏臺灣大學：電信工程學研究所蔡文傑Tsai, Wen-ChiehWen-ChiehTsai2007-11-272018-07-052007-11-272018-07-052007http://ntur.lib.ntu.edu.tw//handle/246246/58577可適性的波束成型技術是個非常重要的研究議題，在現今的無線通訊系統有相當多的應用，像是聲納、雷達等。寬頻的波束成型器提供了很好的寬頻信號接收能力，能有效的降低雜訊和干擾來達到非常高的輸出訊號對雜訊加干擾比。但是當欲接受信號的方向向量和接受端的指引向量有了誤差，亦即二者發生了不匹配(Mismatch)的情況，無法從陣列輸出得到欲接收的信號。為了解決這項在波束成型上的非理想問題，我們利用了寬頻信號的方向向量會和同頻率的雜訊子空間正交的特性[4,5]去建立一個目標函數，利用不同的最佳化方法找出適當的解，再帶入LCMV演算法中算出最佳權重。論文的另一個部份，就是將我們提出的寬頻雜訊子空間投影法延伸到可移動信號源的波束成型技術上，透過這個方法可以估出號源在移動後的指引向量，再將估出來的指引向量代入具指向性的波束成型演算法，透過即時(real time)處理來找到最佳的輸出。最後，提出電腦模擬的結果驗証我們的強健式演算法確實能在有指向誤差或是可移動信號源的環境下運作的非常良好。Adaptive beamforming technique is an important research issue, and it has many applications in wireless communications, such as sonar, radar and so on. Wideband beamformers provide good capability of receiving wideband signals, and it can suppress the noise and the interference effectively to achieve high OutputSINR. However, when there is mismatch between the directional vector of the signal and the steering vector in the receiving side, we can’t get the desired signal from the array output. For solving this nonideal problem, the orthogonality between the directional vector and the noise subspace with the same frequency can be used to establish a cost function. After finding the appropriate solution with the minimum cost function value through different optimization methods, the LCMV algorithm can use the result to calculate the optimum weight. In the other part of the thesis, we extend the wideband noise-subspace projection method to the beamforming of the moving source, and the correct steering vector of the moving source can be estimated. Then the estimated steering vector can be used in the adaptive beamforming algorithm to get the optimum output through real time processing. Finally, computer simulation result can verify that our robust beamforming algorithm can work very well in the environment of the steering angle error or moving sources.致謝................................................... I 摘要.................................................... II Abstract................................................III目錄.................................................... IV 第一章 諸論...............................................1 1.1 研究背景.........................................1 1.2 研究動機.........................................2 1.3 論文貢獻.........................................2 1.4 論文架構.........................................3 第二章 寬頻陣列天線信號處理之數學基礎...................4 2.1 寬頻天線陣列基本架構.................................4 2.1.1 寬頻線性陣列...................................5 2.1.2 寬頻圓形陣列...................................6 2.2 寬頻信號模型.........................................7 2.3 頻譜密度矩陣及其特徵空間.............................8 2.4 可適性波束成型技術(LCMV).............................9 2.5 分割信號及雜訊子空間- AIC & MDL.....................11 第三章 寬頻線性天線陣列對抗方位誤判之強健式波束成型技術..14 3.1 方位誤判簡介....................................14 3.2 寬頻ULA雜訊子空間投影法.........................15 3.2.1單一波束修正........................................15 3.2.2多重波束修正........................................17 3.3 對角線負載(Diagonal Loading)....................18 3.4 變異負載(Variable Loading)......................19 3.5 實驗模擬及比較..................................20 3.6 結論............................................61 第四章 寬頻圓形天線陣列對抗方位誤判之強健式波束成型技術..62 4.1 方位誤判簡介........................................62 4.2 寬頻UCA雜訊子空間投影法.............................63 4.2.1 單一波束修正......................................63 4.2.2 多重波束修正......................................66 4.3 變異負載(Variable Loading)..........................68 4.4 實驗模擬及比較......................................69 4.5 結論.............................................106 第五章 結合移動信號源追縱和波束成型的強健式演算法.......107 5.1 系統概論和信號動態移動模型.......................107 5.2 共軛梯度法.......................................109 5.3 移動信號源波束成型器架構...........................112 5.3.1 結合共軛梯度法之雜訊子空間投影法.............112 5.3.2 可適性演算法.................................115 5.4 實驗模擬.........................................116 5.5 結論...............................................127 第六章 總結及未來方向...................................128 參考文獻................................................129en-US波束成型演算法移動信號源方位誤判Beamforming AlgorithmMoving SourcesDirection of Arrival Mismatchthesis