發(fā)布時間：2018-05-19 18:45

  本文選題：MIMO雷達 + 目標檢測�。� 參考：《西安電子科技大學》2015年博士論文

【摘要】：近年來,多輸入多輸出(multiple-input multiple-output, MIMO)雷達由于其良好的性能受到了學者的廣泛關(guān)注。MIMO雷達具有提高目標檢測性能、提高角度估計準確率及能檢測速率更慢的動目標等諸多優(yōu)勢,在軍事和民事應用中具有廣闊的前景。MIMO雷達通常基于目標和環(huán)境的先驗知識設計波形,而由估計得到的先驗知識不可避免存在誤差,基于此先驗知識得到的優(yōu)化波形的檢測和參數(shù)估計等性能嚴重下降,本文對非準確目標先驗知識MIMO雷達波形優(yōu)化進行了系統(tǒng)的研究,所取得的主要研究成果為：1.目前MIMO雷達中的波形優(yōu)化通常基于某一種而不是整體性能,針對該問題,本文提出一種提高MIMO雷達檢測和參數(shù)估計性能的波形優(yōu)化方法。該方法綜合考慮提高檢測概率、降低參數(shù)估計方差及抑制旁瓣三種性能約束優(yōu)化MIMO雷達的發(fā)射波形相關(guān)矩陣(waveform covariance matrix, WCM)。首先,本文推導了檢測概率及克拉美-羅界(Cramer-Rao bound, CRB)的等價表達式,然后,聯(lián)合最大化主旁瓣差約束,并對各約束條件分別加權(quán),進而可通過靈活調(diào)整加權(quán)系數(shù)以解決實際應用中不同需求的波形優(yōu)化問題。該波形優(yōu)化問題可描述為線性規(guī)劃問題,因而可進行高效求解。仿真實驗中,詳細分析了三種約束條件對雷達性能的影響,實驗結(jié)果驗證了所提方法是有效的。2. MIMO雷達通�；谀繕撕铜h(huán)境的先驗知識設計波形,而由估計得到的先驗知識不可避免存在誤差,基于此先驗知識得到的優(yōu)化波形的檢測和參數(shù)估計等性能下降嚴重。針對此問題,本文提出兩種穩(wěn)健波形設計方法,分別提高MIMO雷達的檢測性能和參數(shù)估計性能。在目標位置誤差和通道誤差有界的條件下,分別構(gòu)造以信噪比(Signal Noise Ratio, SNR)口CRB為代價函數(shù)的優(yōu)化問題。為最大化SNR和最小化CRB,分別給出迭代算法,交替以發(fā)射波形相關(guān)矩陣和通道矩陣誤差為優(yōu)化變量求解,將迭代的每一步轉(zhuǎn)化為凸優(yōu)化問題,從而在最差情況下提高MIMO雷達系統(tǒng)的檢測性能和參數(shù)估計性能。仿真實驗結(jié)果驗證了所提方法能有效改進MIMO雷達的檢測和參數(shù)估計性能。3.傳統(tǒng)MIMO雷達發(fā)射波形設計方法對傳播矩陣誤差敏感,最優(yōu)匹配波形難以得到,進而造成系統(tǒng)的檢測性能嚴重下降。針對該問題,在概率約束條件下,本文提出一種穩(wěn)健的MIMO雷達發(fā)射波形設計方法。該方法考慮最差情況的發(fā)生為小概率事件,基于輸出信噪比低于可接受水平的概率小于中斷概率的約束條件,通過最大化輸出信噪比設計最優(yōu)波形。利用傳播矩陣誤差的概率分布特性,將概率約束轉(zhuǎn)化為凸約束,從而將統(tǒng)計優(yōu)化問題轉(zhuǎn)化為確定性優(yōu)化問題。該方法在傳播矩陣存在誤差情況下以高概率實現(xiàn)系統(tǒng)性能最優(yōu)化。仿真結(jié)果表明所提方法能夠提高輸出信噪比,具有較好的檢測性能。4.均勻圓陣(uniform circular array, UCA)與MIMO雷達的結(jié)合可在不犧牲UCA雷達主要優(yōu)點的同時兼有MIMO雷達的優(yōu)勢。然而,UCA-MIMO雷達的波束形成與距離無關(guān),該特點限制了其抑制特定距離干擾的性能。本文提出頻率分集(frequency diversity, FD)UCA-MIMO雷達距離依賴波束形成方法。該方法中UCA的每個陣元發(fā)射具有微小頻率步進的不同頻率,從而遠場的信號積累與距離有關(guān),進而波束形成依賴于距離。仿真實驗表明了該方法的有效性。
[Abstract]:In recent years, multiple-input multiple-output (MIMO) radar has attracted wide attention from scholars because of its good performance..MIMO radar has many advantages, such as improving target detection performance, improving angle estimation accuracy and moving targets with slower detection rate, and has a broad prospect in military and civil applications,.MIM The O radar usually designs the waveform based on the prior knowledge of the target and the environment, and the estimated prior knowledge inevitably has errors. The performance of the optimized waveform detection and parameter estimation based on this prior knowledge is seriously reduced. This paper systematically studies the waveform optimization of the inaccurate target prior knowledge MIMO radar. The main research results are as follows: 1. at present, waveform optimization in MIMO radar is usually based on one kind but not the whole performance. In this paper, a waveform optimization method to improve the performance of MIMO radar detection and parameter estimation is proposed. This method comprehensively considers the detection probability, reduces the variance of parameter estimation and inhibits the three performance of the sidelobe. Constrained optimization of the emission waveform correlation matrix (waveform covariance matrix, WCM) for MIMO radar. First, this paper derives the equivalent expression of the detection probability and the kratho bound (CRB). Then, the joint maximizes the main side lobe difference constraint and weights the constraints respectively, and then the weighted coefficients can be adjusted flexibly to solve the problem. The waveform optimization problem of different requirements in practical applications. The waveform optimization problem can be described as a linear programming problem and can be efficiently solved. In the simulation experiment, the effects of three constraints on the radar performance are analyzed in detail. The experimental results verify that the proposed method is an effective.2. MIMO radar, which is usually based on the target and the environment. According to the knowledge design waveform, the estimated prior knowledge inevitably has errors. The performance of the optimized waveform detection and parameter estimation based on this prior knowledge is reduced seriously. In this paper, two robust waveform design methods are proposed to improve the detection performance and parameter estimation performance of MIMO Rada respectively. Under the conditions of bounded error and channel error, the optimization problem of the cost function of the Signal Noise Ratio, SNR port CRB is constructed respectively. In order to maximize SNR and minimize CRB, an iterative algorithm is given respectively, which alternately solves the waveform correlation matrix and the channel matrix error as the optimal variable, and transforms each step of the iteration into a convex optimization. In the worst case, the detection performance and parameter estimation performance of the MIMO radar system are improved. The simulation experiment results show that the proposed method can effectively improve the detection and parameter estimation performance of the MIMO radar..3. traditional MIMO radar transmission waveform design method is sensitive to the propagation matrix error, and the optimal matching waveform is difficult to obtain, and then it is built. In this paper, a robust MIMO radar emission waveform design method is proposed under the condition of probability constraints. This method considers the worst case occurs as a small probability event, and is based on the constraint condition that the probability of the output signal to noise ratio is lower than the acceptable level and the maximum loss. The optimal waveform of signal-to-noise ratio is designed. By using the probability distribution characteristic of the propagation matrix error, the probability constraint is converted into a convex constraint, and the statistical optimization problem is transformed into a deterministic optimization problem. The method realizes the optimal performance of the system with high probability in the presence of error of the propagation matrix. The simulation results show that the proposed method can improve the transmission capacity. The combination of.4. uniform circular array (uniform circular array, UCA) with MIMO radar, which has good detection performance, has the advantage of MIMO radar without sacrificing the main advantages of UCA radar. However, the beamforming of the UCA-MIMO radar is independent of the distance. This feature limits its performance to suppress specific distance interference. This paper proposes frequency. Frequency diversity (FD) UCA-MIMO radar range dependent beamforming method. In this method, each element of the UCA has a different frequency with a small frequency step, thus the signal accumulation in the far field is related to the distance, and then the beam formation depends on the distance. The simulation experiment shows the effectiveness of the method.
【學位授予單位】：西安電子科技大學
【學位級別】：博士
【學位授予年份】：2015
【分類號】：TN958

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