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題名 | 應用於行動通訊之簡易式靜態週期性陣列天線=A Simple Cyclostationary Adaptive Array for Mobile Communications |
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作者姓名(中文) | 柳茂林; | 書刊名 | 遠東學報 |
卷期 | 24:3 2007.09[民96.09] |
頁次 | 頁263-272 |
分類號 | 448.813 |
關鍵詞 | 陣列天線; 干擾源; 同頻干擾源; 靜態週期統計特性; 限制性最小均方根方法; 空間平均法則; Adaptive array; Interferer; Coherent interferer; Cyclostationary; Constrained least mean square method; Spatial smoothing method; |
語文 | 中文(Chinese) |
中文摘要 | 行動通訊系統中陣列天線常用來去除干擾源以提昇基地台的系統容量,當訓 練數列不存在時,盲目式陣列天線被拿來解決此類問題,盲目法則中,近來 常使用靜態週期性陣列天線來克服定模數演算法則之收斂速度不足之問題, 但靜態週期性陣列天線通常有計算量太大及無法解決同頻干擾等問題,較不 適合在行動通訊系統中使用,在本文中,我們將提出一種簡易式靜態週期性 陣列天線法則來克服計算量太大及解決同頻干擾之問題,在新的法則中,我 們先估算信號之靜態週期性自相關矩陣,並利用此矩陣的行與列來構成投射 向量,以此投射向量來求出信號的入射方位,再使用限制性最小均方根法則 來推導出陣列天線的最佳權重值,所以不像一般的靜態週期性陣列天線則須 先求出靜態週期性自相關矩陣之特徵值與特徵向量,因此不會有計算量太大 的問題。而且利用信號的靜態週期統計特性來處理接收到的信號,我們可將 一些不相關的信號先行分離,再去估測找出想要接收的信號,所以所須的天 線個數可以較非靜態週期性之陣列天線方法少,此外,即使不相關的干擾源 與想要接收的信號之入射角度靠的很近,亦可將想要接收的信號估測出來, 而雜訊與信號不具相關性,故在陣列天線之靜態週期性自相關矩陣中已事先 將雜訊分離去除,所以即使使用投射式法則亦不會因為要避免雜訊干擾而導 致所需天線數目的增加。但使用投射式的法則卻可較特徵結構法則所須之計 算量少。而且當有同頻干擾源時,陣列天線將無法有效分辨想要接收信號與 同頻干擾源而造成錯誤,此時我們使用簡易式靜態週期性空間平均法則來改 善此一問題,基於上述理由,可發現簡易式靜態週期性陣列天線的方法較一 般陣列天線方法更適合應用於使用者日益增多的行動通訊上。 |
英文摘要 | Adaptive Array has been employed for canceling the co-channel interferers to improve the performance for mobile communications. When the training sequence is absent, the blind adaptive array algorithms have been developed for suppressing the interferers.In those blind methods, the cyclostationary method is converged more fast than the constant module algorithm. But the computation of cyclostationary adaptive array is complicated. In this paper, a simple cyclostationary adaptive array is proposed to overcome many of the limitations of existing techniques. In simple cyclostationary array, the projection vectors is found by the cyclic covariance matrix of the input signal. The arrival angle of the signals are determined by the projection vectors of the cyclic convariance matrix. Then, the weights of adaptive array can be calculated by the constrained least mean square method. The conventional cyclostationary array can suppress the interferers successfully, but it needs to compute the eigenstructure of the cyclic convariance matrix. Therefore, the complicated computation problem will occur in conventional cyclostationary methods. The proposed method can automatically classify signals as correlated or uncorrelated based on the cyclostationary property. Thus, the array in proposed method may need less number of elements than that required by the non-cyclostationary methods, which estimate both the correlated and uncorrelated signals. Besides, the proposed method can resolve two signals spaced more closely than the resolution threshold of the array when only one signal is correlated. Furthermore, the desired signals and noise are uncorrelated in cyclostationary methods. The noise terms are canceled by the property of cyclostationary, therefore the number of elements for the proposed project method array is the same as the other. But the projection method in simple cyclostationary array can be used to reduce the computation time. Besides, when the coherent interferer present,the adaptive array will fail to distinguish the desired signal and the coherent signal. In this paper, we will find a spatial smoothing method to improve this problem. Thus, the use of the proposed method to receive the desired signals is more better than that of the other adaptive array methods for mobile communications. |
本系統之摘要資訊系依該期刊論文摘要之資訊為主。