本文為沙特阿卜杜拉國王科技大學（作者：Seifallah Jardak）的碩士論文，共75頁。

由於多輸入多輸出（MIMO）雷達效能的提高，引起了研究者和工程師的廣泛關注。由於MIMO雷達發射正交或部分相關的波形，這種新興技術通過提供更好的引數可識別性、獲得更高的空間解析度、能夠設計複雜的波束濾波器，因此優於相控陣雷達。為了避免干擾並提高信噪比，在給定感興趣區域中最大化發射功率，並在其它區域最小化發射功率是非常有用的。該問題被稱為發射波束設計，通常分為兩步處理：首先通過最小化凸優化問題設計發射協方差矩陣，然後使用該凸優化表示式產生實際發射波形。

在本文中，我們提出了利用有限字母表常數和非常數包絡符號產生相關波形的簡單方法。為了產生有限的字母波形，提出的方法將高斯隨機變數對映到相移鍵控、脈衝幅度和四邊形幅度調製方案上。對於這種對映，高斯隨機變數的概率密度函式被劃分為M個區域，其中M是相應調製方案中的字母表個數。利用對映函式，推匯出了高斯符號與有限字母符號之間的互相關關係。

論文的第二部分介紹了目標引數估計問題。為了確定目標的反射係數、空間位置和多普勒頻移，採用最大似然估計的方法得到最佳效能。然而，最大似然估計涉及到一個兩維搜尋的問題，因此演算法計算量巨大。因此我們提出了一種降低演算法複雜度的次優演算法，採用二維快速傅立葉變換聯合估計空間位置和多普勒頻移。為了評估本文所提出的估計器效能，推導了CRLB。模擬結果表明，所提出估計器的均方估計誤差達到了CRLB的水平。

Thanks to its improved capabilities, theMultiple Input Multiple Output (MIMO) radar is attracting the attention ofresearchers and practitioners alike. Because it transmits orthogonal orpartially correlated waveforms, this emerging technology outperformed thephased array radar by providing better parametric identifiability, achievinghigher spatial resolution, and designing complex beampatterns. To avoid jammingand enhance the signal to noise ratio, it is often interesting to maximize thetransmitted power in a given region of interest and minimize it elsewhere. Thisproblem is known as the transmit beampattern design and is usually tackled as atwo-step process: a transmit covariance matrix is firstly designed by minimizinga convex optimization problem, which is then used to generate practicalwaveforms. In this work, we propose simple novel methods to generate correlatedwaveforms using finite alphabet constant and non-constant-envelope symbols. Togenerate finite alphabet waveforms, the proposed method maps easily generatedGaussian random variables onto the phase-shift-keying, pulse-amplitude, andquadratureamplitude modulation schemes. For such mapping, the probabilitydensity function of Gaussian random variables is divided into M regions, whereM is the number of alphabets in the corresponding modulation scheme. Byexploiting the mapping function, the relationship between the cross-correlationof Gaussian and finite alphabet symbols is derived. The second part of thisthesis covers the topic of target parameter estimation. To determine thereflection coefficient, spatial location, and Doppler shift of a target, maximumlikelihood estimation yields the best performance. However, it requires a twodimensional search problem. Therefore, its computational complexity isprohibitively high. So, we proposed a reduced complexity and optimumperformance algorithm which allows the two dimensional fast Fourier transformto jointly estimate the spatial location and Doppler shift. To assess theperformance of the proposed estimators, the Cram′er Rao Lower Bound (CRLB) isderived. Simulation results show that the mean square estimation error of theproposed estimators achieve the CRLB.

1 引言
2 發射波束形成與波形設計
3 目標引數估計
4 結論與評論

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