MIMO雷达波形设计与实时处理系统研究

发布时间：2018-05-31 05:36

本文选题：多输入多输出雷达 + 波形设计　；参考：《西安电子科技大学》2014年博士论文

【摘要】：多输入多输出(Multi-Input Multi-Output, MIMO)雷达是目前雷达技术领域的研究热点，其特点是每个发射天线可以独立发射不同的波形，与相控阵雷达所有阵元发射相同的波形相比，MIMO雷达的波形分集能力带来更多的发射自由度。可以通过设计发射波形灵活地设计期望发射方向图的形状。同时，MIMO雷达的波形分集能力是提高雷达资源利用率、实现雷达资源自适应分配调度的重要手段。本论文结合具体科研任务，主要围绕窄/宽带MIMO雷达的波形设计、稳健自适应波束形成方法和新型雷达实时信号处理系统等问题展开研究。论文的内容可概括为如下四个部分：第一部分研究了窄带MIMO雷达发射波形设计方法。针对窄带MIMO雷达在给定的期望发射波束方向图情况下，如何在线快速设计具有良好的自相关和互相关性能的发射波形问题，提出了基于协方差矩阵空时构造的MIMO雷达发射波形设计方法。首先将发射波形矩阵分解为空域方向矩阵和时域信号矩阵。然后通过一组发射导向矢量构造空域方向矩阵，通过利用MUSIC方法获得这组发射导向矢量的指向角度，而时域信号矩阵是由(0,1)矩阵和离线设计的正交波形集构造获得。实验结果表明该方法避免了复杂的迭代和优化过程，与已有方法相比，所提方法具有相近的发射方向图综合性能，但其计算复杂度明显降低。第二部分研究了宽带MIMO雷达发射波形设计方法。首先针对一维均匀线阵宽带MIMO雷达，提出了一种一维宽带MIMO雷达频率不变发射方向图快速综合方法，该方法首先利用均匀线阵的发射方向图与发射波形的频谱具有一维傅立叶变换的关系，，去除了发射方向图与发射波形频率的相关性；然后建立了具有恒模约束条件的时域波形最优匹配频率响应的代价函数；最后采用交替优化的思想求解出恒模发射波形。为了匹配二维宽带MIMO雷达系统给定的期望发射方向图，将一维均匀线阵情况下提出的方法进行扩展，通过空域、频域变量的代换及二维逆傅立叶变换去除了发射方向图与波形频率的相关性。并且通过交替优化求解得到具有恒模性质的时域宽带发射波形。提出的方法能够有效地改善宽带MIMO雷达发射波束方向图频率色散问题，并且避免了多维优化问题中复杂的多维搜索，明显降低了运算复杂度，仿真实验验证了所提方法的有效性。第三部分研究了稳健自适应波束形成方法。针对导向矢量失配和样本协方差矩阵估计误差导致自适应波束形成性能下降的问题，提出一种基于波束域导向矢量估计的稳健方法。该方法首先利用期望信号角度失配区域的补集构造波束域转换矩阵，克服了当样本协方差矩阵中存在期望信号分量时现有算法出现有用信号对消的缺点。其次推导出波束域导向矢量估计方法，并将其转化为包含恒模约束的非凸二次约束二次规划问题，然后采用半正定松弛规划估计实际的波束域导向矢量。仿真验证了所提方法的有效性。第四部分研究了新型雷达实时信号处理系统。针对新型雷达系统（如MIMO雷达，认知雷达等）的结构特点，首先对雷达实时信号处理系统的体系结构、通用性设计等关键技术进行了研究。提出了一种基于交换的开放式雷达系统架构，该系统架构简化了复杂的异构多模块互连方式，有助于提高任务分配、软件设计和调试的效率，并适用于不同需求的雷达系统。然后在此系统架构下，设计了一种新型通用雷达实时信号处理机，该信号处理机采用模块化设计，具有处理能力强，维护扩展性好，可靠性高等特点。最后结合MIMO数字阵雷达系统的具体应用，设计了核心算法节点的任务分配方案，包括窄带MIMO接收处理、宽带波束形成和ISAR成像，并且分析了任务分配方案的实时性能。由于设计的新型通用雷达实时信号处理机具有良好的体系架构，通过配置不同的处理功能模块可以应用于不同的实时信号处理场合。
[Abstract]:Multi-Input Multi-Output (MIMO) radar is a hot spot in the field of radar technology. Its characteristic is that each transmitting antenna can transmit different waveforms independently. Compared with all the same waveforms from the array elements of the phased array radar, the waveform diversity of the MIMO radar brings more free degree of freedom. The shape of the expected emission pattern is designed flexibly by the emission waveform. At the same time, the waveform diversity of the MIMO radar is an important means to improve the utilization of radar resources and realize the adaptive allocation and scheduling of radar resources. This paper, combined with specific research tasks, mainly focuses on the waveform design of narrow / wideband MIMO rea and robust adaptive beamforming. The problems of the method and the new radar real-time signal processing system are studied.
The content of this paper can be summarized as four parts as follows:
In the first part, the design method of the emission waveform of the narrow band MIMO radar is studied. In the case of the given desired emission beam pattern of the narrowband MIMO radar, how to quickly design the transmission waveform with good autocorrelation and intercorrelation performance on line is proposed, and the design side of the MIMO radar emission waveform based on the covariance matrix space time structure is proposed. First, the emission waveform matrix is decomposed into space direction matrix and time domain signal matrix. Then, the direction matrix of the space domain is constructed by a group of emission guidance vectors, and the direction angle of the emission guidance vector is obtained by using the MUSIC method, and the time domain signal matrix is constructed by the (0,1) matrix and the off-line orthogonal waveforms set. The experimental results show that the proposed method avoids the complex iteration and optimization process. Compared with the existing methods, the proposed method has a similar comprehensive performance of the emission pattern, but its computational complexity is obviously reduced.
In the second part, the design method of the wideband MIMO radar emission waveform is studied. Firstly, a fast synthesis method of one dimensional broadband MIMO radar with wideband MIMO radar frequency invariant emission is proposed. The method first uses the emission pattern of uniform linear array and the spectrum of the firing waveform to have one dimensional Fu Liye transform. The relationship between the emission pattern and the frequency of the emission waveform is removed; then the cost function of the optimal matching frequency response of the time domain waveform with constant mode constraints is established. Finally, the constant mode emission waveform is solved by the idea of alternating optimization. In order to match the desired emission pattern given by the two-dimensional wide-band MIMO radar system, the desired emission pattern will be matched. The method proposed in one dimensional uniform linear array is extended. The correlation between the emission pattern and the waveform frequency is removed through the space domain, the frequency domain variable substitution and the two-dimensional inverse Fu Liye transform, and the time-domain wideband emission waveform with constant mode properties is obtained by alternating optimization. The proposed method can effectively improve the broadband MIMO mine. The frequency dispersion of the beam pattern is solved, and the complex multidimensional search is avoided in the multidimensional optimization problem. The computational complexity is obviously reduced. The simulation experiment proves the effectiveness of the proposed method.
In the third part, a robust adaptive beamforming method is studied. In view of the problem of adaptive beamforming performance degradation resulting from the guidance vector mismatch and the sample covariance matrix estimation error, a robust method based on the beam domain guidance vector estimation is proposed. This method first constructs the beam using the complement set of the desired signal angle mismatch region. The domain transformation matrix overcomes the shortcoming that the existing algorithm appears useful signal cancellation when the expected signal component exists in the sample covariance matrix. Secondly, the beam domain guidance vector estimation method is derived, and it is transformed into a non convex two order constraint two order programming problem with constant modulus constraints, and then the semi positive definite relaxation programming is used to estimate the actual situation. Simulation results show that the proposed method is effective.
In the fourth part, the new radar real-time signal processing system is studied. In view of the structural features of the new radar system (such as MIMO radar, cognitive radar, etc.), the architecture of the radar real-time signal processing system and the general design of the key technologies are studied. An open radar system architecture based on exchange is proposed. The architecture simplifies the complex heterogeneous multi module interconnection mode, and helps to improve the task allocation, the efficiency of software design and debugging, and is applicable to different radar systems with different requirements. Then, under the framework of this system, a new type of Universal Radar Real-time signal processor is designed. The signal processor is modular design with strong processing capacity and dimension. In the end, based on the application of the MIMO digital array radar system, the task allocation scheme of the core algorithm nodes is designed, including the narrowband MIMO receiving processing, the broadband beamforming and the ISAR imaging, and the real-time performance of the task allocation scheme is analyzed. The machine has good architecture and can be applied to different real-time signal processing situations by configuring different processing modules.
【学位授予单位】：西安电子科技大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TN957.51

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