MIMO radar waveform design method via low sidelobe beampattern modification

In the design of the multiple-input multiple-output(MIMO) radar waveform, decreasing transmit beampattern sidelobes could reduce the energy of clutters and false targets from sidelobes and increase the received signal to noise ratio (SNR) so as to improve the angle estimation property. Motivated by this idea, a transmit waveform design method based on low sidelobe beampattern modification is proposed for MIMO radar. First, the transmit waveform cross-correlation matrix can be obtained by the semidefinite relaxation (SDR) technique. Then the essence of our method is to establish an optimization modification model to reduce the beampattern sidelobe by changing the non-diagonal elements of the waveform cross-correlation matrix. Finally, the corresponding transmit beamforming weight matrix is obtained by this modified matrix, and the ESPRIT algorithm is used for the direction of arrival (DOA) estimation. Meanwhile, the feasibility of our method is demonstrated. Simulation results show the superiorities of our method in sidelobe suppression, DOA estimation accuracy and angle resolution.     

MIMO雷达发射方向图匹配和波形优化方法

为了匹配MIMO雷达系统给定的发射方向图,采用半正定规划(SDP)来优化发射信号的协方差矩阵．基于该协方差矩阵,利用循环算法(CA)和极小极大法,通过优化波形相位设计出了具有低空域和时域副瓣的恒模发射信号．此外,又提出了用凸规划设计空域失配滤波器和时域失配滤波器的方法,进一步降低了空域和时域副瓣．     

联合优化方向图合成与频谱兼容的MIMO雷达波形设计

多发射-多接收雷达发射方向图合成是当前波形设计和合成问题的热点,其目的在于实现将发射能量聚焦在感兴趣的空域方向上.而在复杂的电磁环境中,还必须兼顾考虑在拥堵频段上的频谱兼容性和灵活性,避免影响邻近频段通信系统传输性能.该文提出算法设计MIMO雷达发射波形向目标空域聚焦能量的同时,避开拥堵频段的频率范围.即针对发射波形在...     

Waveform Design for MIMO Radar with One-Bit DACs via Block-Sparse Semidefinite Relaxation

Multiple-input multiple-output (MIMO) systems which deploy one-bit DACs are at-tractive in many fields, such as wireless communications and radar. In this paper, the problem of transmit waveform design in MIMO radar system with one-bit DACs is investigated. By appropri-ately designing the transmitted QPSK signal waveforms, the majority of radiated energy can be fo-cused into the mainlobe region(s) by minimizing the integrated sidelobe to mainlobe ratio (ISMR) of beampattern, such that the intensity of backscattered signals from targets can be enhanced. However, the resulting optimization problem which consists of constrained fractional quadratic problem (CFQP) is noconvex. To tackle this problem, a block-sparse semidefinite relaxation meth-od is first utilized to reformulate the CFQP into a reduced convex semidefinite programming (SDP). Further, a customized interior point algorithm (IPA) is developed to solve the small-scale SDP. Finally, the desirable one-bit transmit waveform sequence can be properly synthesized by us-ing Gaussian randomization method. Numerical simulation results demonstrate that the proposed method offer better performance than the state-of-the-art algorithms.     

一种空时联合优化的MIMO雷达波形设计方法

针对多输入多输出(MIMO)雷达波形设计中空域合成信号的时域特性较差的情况,提出了一种空时联合优化的MIMO雷达波形设计方法．该方法在波形设计中对波形的空域功率分布以及空域合成信号的自相关特性进行了联合考虑．基于空域信号的自相关旁瓣电平以及各阵元信号间的相关性,对集中式MIMO雷达的正交波形设计与具有特定方向图的波形设计建立了统一的优化模型,并采用序列二次规划方法与加权迭代方法求解．仿真结果表明,文中所设计的波形不仅能够很好地逼近期望方向图,而且空域合成信号具有较好的自相关特性．     

双基地MIMO雷达波形解相关算法

The auto-correlation and cross-correlation properties of transmit waveforms have great effects on the performance of MIMO radar systems. However, it is difficult to design waveforms that have ideal auto-correlation properties as well as cross-correlation ones. In this paper, an MMSE based waveform de-correlation algorithm is proposed to cancel the effects of the auto-correlation and cross-correlation of transmit waveforms in the receiver. The received signal model of bistatic MIMO radars is first derived. Then, the de-correlation filters are derived by using the MMSE method to reduce the influences of colored noise enhancement. Finally, the polynomial expansion method is used to simplify the computational complexity of the proposed de-correlation filters. The performance of the proposed method is verified by applying it to bistatic MIMO radar multi-target localization. Simulation results demonstrate the effectiveness of the proposed algorithm.     

采用OFDM-LFM的MIMO雷达高速目标波形设计

单基地多输入多输出雷达由于其宽发射波束的特性而能有效解决目标高速运动跨越发射波束带来的能量损失问题;但是现有波形对速度容忍性较差,高速目标回波匹配滤波能量损失较大．因此,有必要研究适用于高速目标背景下的多输入多输出雷达波形． 文中提出了一种基于正交频分复用线性调频信号的多输入多输出波形． 该波形不同发射通道分时复用一组不同频段的线性调频信号,从而得到带宽相同的可分离多路多输入多输出雷达波形． 仿真结果表明,文中设计的多输入多输出雷达波形能有效降低高速目标回波匹配滤波的能量损失,适用于高速目标背景．     

MIMO radar waveform design in the presence of clutter and colored noise

The existing MIMO radar waveform design methods only deal with the optimization of radar waveform with the presence of clutter or colored noise, and unfortunately can not get the optimal waveform with the scenario when the clutter and colored noise coexist, which is more realistic in practical applications. To address this problem, a novel MIMO radar waveform design method based on mutual information in the presence of clutter and colored noise is proposed. The proposed scheme considers the influence of the target's response, clutter and colored noise on the optimization of the radar waveform. The mathematical expression for the transmit waveform matrix is achieved by theoretical derivation. What is more important, an optimal pairing of the eigenvectors of the target, clutter and colored noise is given and the power allocation for each antenna is optimized by the water-filling method. Simulation results show that when the total transmit power is 10dB, the proposed method's MI is 8bit and 4bit more than that of the general water-filling method and the method which only considers the pairing of the target's response and noise, respectively.     

稳健的MIMO雷达发射波形和接收滤波器联合优化设计

针对杂波条件下目标反射信号方向不确定的情况,提出一种稳健的MIMO雷达发射波形和接收滤波器联合优化设计方法.在考虑各阵元发射功率相等的约束条件下,利用发射加权矩阵构造不确定集范围内关于输出信干噪比(SINR)的Maxmin优化模型;在此基础上,利用序列优化、半正定松弛和Charnes-Cooper转换,将非凸的联合优化问题转化为关于发射波形和接收滤波器的凸优化问题进行迭代求解;最后通过随机向量合成方法计算最终发射波形和接收滤波器,并对算法计算复杂度和收敛性给出分析和证明.所提方法在满足阵元发射功率一致的约束条件下,提高了算法稳健性并降低了计算复杂度.仿真实验证明了算法的有效性.     

双基地MIMO雷达目标定位及互耦自校正算法

利用均匀线阵互耦矩阵的带状和对称Toeplitz特性,提出了一种基于旋转不变技术估计目标参数(ESPRIT)的双基地多输入多输出(MIMO)雷达目标定位及互耦自校正算法.该算法通过ESPRIT算法中子阵的选取,将目标二维方位角估计与互耦参数估计相"去耦",角度估计过程不需任何互耦矩阵信息,且估计精度高、分辨力强;基于对目标二维方位角的估计,算法还可以精确地估计出互耦矩阵,从而实现双基地MIMO雷达的互耦自校正.该算法对目标二维方位角与互耦矩阵的估计不涉及任何角度搜索和迭代过程,具有较小的运算量.计算机仿真结果证明了该算法的正确性和可行性。     

MIMO雷达中的DFCW设计及性能分析

发射信号的正交性好坏是多输入多输出(MIMO)雷达实现的关键,正交离散频率编码波形(DFCW)是MIMO雷达可以利用的正交信号。该文首先分析了DFCW的互模糊函数,在此基础上,对自相关峰值旁瓣及互相关峰值旁瓣电平进行了分析,提出了采用遗传算法对其进行优化,得到了具有更低互相关峰的DFCW。然后将优化得到的DFCW应用于MIMO雷达系统进行仿真分析。通过对信号互相关仿真及对目标回波信号匹配滤波仿真对理论分析进行了验证,证明了理论分析的正确。     

Static beamforming method of frequency diverse array

Focused on the time-varying property of the transmit beampattern of the frequency diverse array, a static transmit beamforming method is proposed to control the beampattern of the pulsed frequency diverse array, and the characteristics of its radiating pattern are studied. With a tiny progressive incremental frequency shift applied between the adjacent antenna elements, a range-angle dependent radiating pattern is achieved. Compared with the conventional phased array, the frequency diverse array is low in price and small in complexity without the use of phase shifters, which enables it to be suitable for the miniaturization design of an array antenna. Moreover, its range-angle dependent characteristic significantly enhances the flexibility of antenna beam scanning. Simulation experiments demonstrate the effectiveness of the proposed method.     

FRFT域LFM雷达回波信号的压缩采样模型

针对宽带雷达线性调频信号(Linear Frequency Modulated,LFM)带宽大、采样率高、存储容量要求高的问题,设计了一种基于压缩感知的 LFM雷达回波信号的欠采样整体方案。首先,利用 LFM信号在分数阶傅里叶变换(FRactional Fourier Transform,FRFT)域上良好的能量聚集特点,提出了一种基于DFRFT核矩阵的正交基字典构造方法,在此基字典的基础上利用随机解调器和匹配追踪类算法构建了一个 LFM雷达回波信号的压缩采样和重构系统模型。仿真结果验证了 FRFT域处理 LFM雷达回波信号的可行性和有效性,LFM雷达信号在该正交基字典上的稀疏表示效果要优于现有的波形匹配字典,而且具有更好的抗噪性能和自适应性能。     

一种新型六边形宽带毫米波MIMO天线

提出了一种六边形开槽结构的宽带毫米波多天线技术(MIMO)天线。该微带天线的贴片为六边形采用共面波导馈电方式,并通过开槽拓宽天线的带宽,没有添加隔离枝节,可实现隔离度小于-20 dB,尺寸为23.6 mm×15.4 mm×0.1 mm。通过电磁仿真软件HFSS对设计的天线单元及MIMO天线进行了仿真与分析结果发现,该毫米波MIMO天线在5.1～41.8 GHz频率范围内回波损耗均小于-10 dB,并且具有良好的辐射特性。     

MIMO雷达空时编码和接收权联合稳健设计

针对基于多进多出雷达的空时自适应处理方法的检测性能对目标参数估计误差敏感从而导致系统检测概率稳健性较差的问题,提出一种改善多进多出空时自适应检测性能的发射波形和接收权联合稳健设计方法。首先推导了多进多出空时自适应输出信干噪比的数学表达,而后构建了目标空时频导向矢量估计误差模型。在此误差模型、波形恒模特性、旁瓣以及杂波抑制等约束下,基于最大化最差情况下输出信干噪比准则,提出了改善多进多出空时自适应检测性能的发射波形相关阵和接收权联合稳健优化问题。为求解所得复杂非线性优化问题,提出一种迭代方法,其中每一步都可转化为半定规划问题,因而可获得高效求解。仿真结果表明,与现存主要的稳健方法、非稳健方法及不相关波形相比,所提方法可显著改善多进多出空时自适应检测概率的稳健性能。     

基于遗传算法的MIMO雷达离散频率编码波形设计

针对MIMO雷达体制的离散频率编码波形设计问题，给出了一种采用遗传算法对频率编码序列的选取进行优化组合的方法．首先对波形设计的代价函数进行了改进，然后针对离散频率编码的特点，对遗传算法的选择、交叉、变异算子进行了设计，最后对设计结果进行了分析．结果表明，该方法要优于模拟退火算法．     

星载多发多收SAR多维编码波形设计与分析

多发多收合成孔径雷达(MIMO SAR)解决了传统SAR存在的高分宽幅矛盾。为提高MIMO SAR对通道之间干扰能量的抑制能力,采用多维波形编码技术进行系统设计,并研究了MIMO SAR的波形设计问题。针对两种新型信号形式：正负线调频信号及正交频分复用调制线调频信号,与短时移正交信号(STSO)进行对比分析及成像实验验证。根据MIMO SAR多个孔径同时发射信号、多个孔径同时接收回波的特点,结合多维波形编码技术进行回波处理。在俯仰维,利用数字波束合成技术进行多个子测绘带的划分,实现大测绘带成像;在方位维,利用多通道重构算法将周期非均匀采样的回波恢复为均匀采样,实现高分辨率成像,在此基础上开展新体制SAR发射信号的设计与成像实验验证。实验结果表明,较之其他两种信号,STSO信号的峰值旁瓣比、积分旁瓣比及分辨率等性能最优,对模糊能量抑制更为彻底,在MIMO SAR中性能良好,与传统SAR的性能近似。STSO在MIMO SAR体制中具有良好聚焦性能,且各项成像指标良好,在一定程度可降低系统设计的复杂度。     

MIMO Radar Waveform Design: An Overview

Waveform or code design is an important topic in many applications, which has continuously attracted attention during the past several decades. The development of waveform design has been significantly advanced since the emergence of multiple-input multiple-output(MIMO) technique. Compared to the single-waveform design for conventional radars, the multi-waveform design enables extra degrees of freedom(DOFs) for modern radars, which therefore triggers a series of relevant studies on MIMO radar. In this paper, we provide an overview on the main techniques of MIMO radar waveform designs developed in recent years, wherein the state-of-the-art methods are reviewed in terms of different designing criteria, including the minimization of auto-and cross-correlation levels(or equivalently, the integrated sidelobe level), the information theoretic, ambiguity function shaping, and signal-to-interference-plus-noise ratio maximization-based criteria, etc.Moreover, we give detailed comments on the main issues of different waveform designs, and also provide the possibly emerging directions toward the research on MIMO radar waveform design and potential challenges.     

MIMO雷达正交频分LFM信号设计及性能分析

多输入多输出(MIMO)雷达是最近提出的新的雷达技术,在发射端全向发射正交信号,在接收端对接收信号进行匹配滤波处理来恢复发射信号分量,因而信号的正交性好坏是MIMO雷达实现的关键。该文分析了正交频分线性调频(OFDLFM)信号的互模糊函数,对互相关峰值旁瓣电平出现的位置及幅度大小进行了分析,给出了最小化OFD-LFM信号间互相关影响的参数之间的关系。通过对信号互相关的仿真结果及对目标回波信号匹配滤波的仿真结果,证明了理论分析的正确性。     

Design of the broadband microstrip array antenna for blast furnace surface monitoring

Aiming at the requirements of high-resolution imaging and high integration of the blast furnace radar,this paper presents a method for designing a wideband microstrip array antenna,which broadens the antenna bandwidth through the design of parasitic patches and air layers.By combining multi-input multi-output (MIMO) radar and synthetic aperture radar (SAR) imaging principles,a linear MIMO array is designed,and a near-field simulation imaging experiment is performed on the simulated feed line through the wave number domain imaging algorithm.Simulation results show that the gain of the main lobe of the antenna can reach 14.05 dBi,the reflection coefficient is less than -10 dB,the absolute bandwidth is 5.25 GHz,the operating frequency is 20.67~25.92 GHz,and the range resolution is increased to 3 cm compared with the existing blast furnace radar.The average error of the azimuth direction of the simulated material line imaging is 0.008 m,and the range direction is 0.0011 m.Compared with the traditional microstrip array antenna,this antenna effectively widens the bandwidth,and the range resolution is higher than that of the traditional blast furnace radar.It can accurately obtain the shape information on the simulated material line,and has an engineering application value for blast furnace surface monitoring.