本文選題：陣列信號處理 + 寬線性波束形成�。� 參考：《中國科學(xué)技術(shù)大學(xué)》2014年博士論文

【摘要】：波束形成(Beamforming)技術(shù)是陣列信號處理領(lǐng)域中的一個(gè)重要研究方向,其利用空間多傳感器所組成傳感器陣列來對空間信號進(jìn)行發(fā)射或接收,廣泛應(yīng)用于雷達(dá),聲吶,無線通信等領(lǐng)域。傳統(tǒng)的波束形成技術(shù)假設(shè)信號是圓的、平穩(wěn)的,僅僅利用了觀測矢量的協(xié)方差矩陣,然而在通信領(lǐng)域大量的人工調(diào)制信號都是非圓的、非平穩(wěn)的,不僅存在協(xié)方差矩陣而且存在偽協(xié)方差矩陣�；趫A信號假設(shè)下的波束形成技術(shù)雖然可以應(yīng)用于非圓信號,但是其性能并不能達(dá)到最優(yōu)。近些年現(xiàn)代信號處理領(lǐng)域中同時(shí)利用觀測矢量及其共軛的寬線性(WL Widely Linear)技術(shù)的不斷發(fā)展促使研究者們重新審視針對非圓信號的波束形成問題。寬線性波束形成技術(shù)通過分析信號的非圓性,同時(shí)利用了觀測矢量的協(xié)方差矩陣和偽協(xié)方差矩陣,相應(yīng)地一系列寬線性波束形成方法也陸續(xù)出現(xiàn)。 本文在對寬線性波束形成技術(shù)進(jìn)行概述的基礎(chǔ)上,針對寬線性波束形成技術(shù)發(fā)展中存在的關(guān)鍵問題,開展基于非圓系數(shù)估計(jì)的寬線性波束形成算法研究。本研究工作的目的是在解決期望信號非圓系數(shù)估計(jì)問題的基礎(chǔ)上,針對不同場景提出相應(yīng)的寬線性波束形成算法。本論文研究工作的主要貢獻(xiàn)與創(chuàng)新點(diǎn)歸納如下 1.針對最優(yōu)寬線性波束形成算法中非圓系數(shù)難以估計(jì)的問題提出非圓系數(shù)估計(jì)算法,并得到了一個(gè)穩(wěn)健的對角加載權(quán)重矢量。我們研究使用最小功率無畸變(MPDR)準(zhǔn)則,將其轉(zhuǎn)化為一個(gè)參數(shù)估計(jì)問題,通過求導(dǎo)得到初始估計(jì)后,分析干擾和噪聲對初始估計(jì)的影響,最后得到一個(gè)修正的估計(jì)值。在得到非圓系數(shù)估計(jì)后,使用對角加載技術(shù)減小估計(jì)誤差對算法性能的影響。理論與仿真實(shí)驗(yàn)同時(shí)證明所提算法對非圓系數(shù)有比較好的估計(jì)性能,而且能有效地應(yīng)用于實(shí)際場景。 2.針對期望信號存在偏移頻率的情況提出了頻移寬線性波束形成算法。由于存在偏移頻率的期望信號非圓系數(shù)隨觀測時(shí)間逐漸趨于零,共軛觀測矢量與觀測矢量中關(guān)于期望信號的相關(guān)信息是逐漸減少的。我們提出使用共軛循環(huán)觀測矢量代替共軛觀測矢量,其對應(yīng)的共軛循環(huán)相關(guān)系數(shù)代替非圓系數(shù)進(jìn)行寬線性波束形成。所提的算法在偏移頻率為零時(shí),等價(jià)于最優(yōu)寬線性波束形成算法,在偏移頻率不為零時(shí),優(yōu)于最優(yōu)寬線性波束形成算法。此外針對期望信號是直線信號的情況,通過分析時(shí)間平均的非圓系數(shù)與偏移頻率的關(guān)系,提出了兩種估計(jì)偏移頻率的算法。 3.當(dāng)期望信號的偏移頻率與干擾的偏移頻率不同時(shí),提出M階頻移寬線性波束形成算法。頻移寬線性波束形成算法僅利用了期望信號的共軛循環(huán)相關(guān)函數(shù),當(dāng)期望信號的偏移頻率與干擾的偏移頻率不同時(shí),考慮使用多個(gè)共軛循環(huán)相關(guān)觀測矢量,通過增加M個(gè)約束使其干擾在對應(yīng)于他們自己的循環(huán)頻率上的輸出為零。所提算法是頻移寬線性波束形成算法的擴(kuò)展版本,不增加約束的零階算法對應(yīng)著頻移寬線性波束形成算法。當(dāng)期望信號的偏移頻率與干擾的偏移頻率不同時(shí),所提算法優(yōu)于頻移寬線性波束形成算法。 4.針對期望信號存在導(dǎo)向矢量失配的情況,引入非圓系數(shù)空間譜,提出了基于非圓系數(shù)空間譜估計(jì)的穩(wěn)健寬線性波束形成算法。所提算法重構(gòu)了干擾加噪聲協(xié)方差矩陣和干擾加噪聲偽協(xié)方差矩陣,剔除了擴(kuò)展的協(xié)方差矩陣中的信號分量。在高信噪比和小快拍情況下,波束形成器輸出信干噪比始終接近最優(yōu)值。
[Abstract]:Beamforming (Beamforming) technology is an important research direction in the field of array signal processing. It is widely used in radar, sonar, wireless communication and so on. It is widely used in radar, sonar, wireless communication and so on. The traditional wave beam forming technique assumes that the signal is round, stable and only profit. The covariance matrix of the observed vector is used. However, in the field of communication, a large number of artificial modulation signals are noncircular and nonstationary. There is not only a covariance matrix but also a pseudo covariance matrix. The beamforming technology based on the circular signal hypothesis can be applied to the non circular signal, but its performance is not optimal. In the field of modern signal processing, the continuous development of the wide linear (WL Widely Linear) technology using observation vectors and its conjugate has prompted researchers to reexamine the beamforming problem for non circular signals. Wide linear beamforming technology uses the covariance matrix and pseudo covariance of the observation vector by analyzing the non roundness of the signal. Correspondingly, a series of wide linear beamforming methods have also appeared.
On the basis of the broad linear beamforming technology, this paper studies the wide linear beamforming algorithm based on the non circular coefficient estimation, aiming at the key problems in the development of the wide linear beamforming technology. The purpose of this study is to solve the problem of the estimation of the non circular coefficient of the expected signal and to the different scenes. The corresponding broad linear beamforming algorithm is proposed. The main contributions and innovations of this paper are summarized as follows.
1. the noncircular coefficient estimation algorithm is proposed for the problem of non circular coefficients in the optimal wide linear beamforming algorithm, and a robust diagonal loading weight vector is obtained. We use the minimum power distortion free (MPDR) criterion to transform it into a parameter estimation problem and analyze the interference after the initial estimation is obtained by the derivation. The effect of the noise on the initial estimation is finally obtained. After the estimation of the noncircular coefficient, the diagonal loading technique is used to reduce the effect of the estimation error on the performance of the algorithm. The theoretical and simulation experiments show that the proposed algorithm has a better performance for the non circular coefficients and can be effectively applied to the actual scene.
2. a frequency shift width linear beamforming algorithm is proposed for the frequency shift frequency of the expected signal. The correlation information between the conjugate observation vector and the observed vector is gradually reduced because the expected signal non circle coefficient of the expected signal tends to zero with the observation time. We propose to use the conjugate cycle observation vector. The proposed algorithm is equivalent to the optimal wide linear beamforming algorithm when the offset frequency is zero. The proposed algorithm is superior to the optimal wide linear wave beam formation algorithm when the offset frequency is not zero. In addition, the desired signal is a linear signal. By analyzing the relationship between the time averaged noncircular coefficient and the offset frequency, two algorithms for estimating the offset frequency are proposed.
3. the M order frequency shift width linear beamforming algorithm is proposed when the expected signal's offset frequency is different from the interference frequency. The frequency shift width linear beamforming algorithm only uses the conjugate cycle correlation function of the expected signal. When the expected signal's offset frequency is different from the interference frequency, the multiple conjugate cycle correlation concept is considered. The proposed algorithm is an extended version of the frequency shift width linear beamforming algorithm, and the zero order algorithm of the constraints corresponds to the frequency shift width linear beamforming algorithm. The offset frequency of the expected signal number is different from the interference frequency. The proposed algorithm is better than the frequency shift linear beamforming algorithm.
4. a robust wide linear beamforming algorithm based on the noncircular coefficient spatial spectrum estimation is proposed in the case of a non circular coefficient space spectrum. The proposed algorithm reconstructs the interference plus noise covariance matrix and the interference plus noise pseudcovariance matrix, and eliminates the signal points in the extended covariance matrix. In the case of high SNR and small snapshot, the output signal to noise ratio of the beamformer is always close to the optimal value.

【學(xué)位授予單位】：中國科學(xué)技術(shù)大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TN911.7

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