集中式 MIMO 雷达部分相关波形设计与处理

该文针对集中式 MIMO 雷达发射方向图设计与波形设计无法分离,以及接收端如何提取信号多样性自适应地抑制杂波和干扰这两个问题,展开了深入研究.首先,给出了一种改进的快速发射波束形成算法,该算法能够有效地将发射方向图设计和波形设计分离.同时,为了避免发射信号相关矩阵出现奇异性导致信号多样性无法提取的问题,提出了采用特征值加载修正信号相关矩阵的方法.接着,给出了采用上述发射波形的 MIMO 雷达的接收阵列信号处理框架,证明了经过匹配处理后的阵列输出可以最大程度地恢复信号多样性信息.仿真实验表明,采用这种部分相关发射波形的 MIMO 雷达仍然能够充分利用信号多样性带来的额外自由度,有效抑制干扰和杂波.     

多载频MIMO雷达解速度模糊及综合处理方法

多载频MIMO雷达采用稀布阵发射多载频FMCW信号,阵列接收目标回波。该文分析了多载频MIMO雷达的信号模型,提出了一种解速度模糊的新方法,该方法不需发射多重频信号,利用各发射通道模糊多普勒频率获得目标真实速度的最小二乘解。还提出了一种新的发射接收综合处理方法,该方法将积累后每个距离单元等分成Nn份,并用相参积累结果对其加权,在抑制距离栅瓣的同时充分利用了收发阵列孔径。最后讨论了多载频MIMO雷达的参数选取问题。仿真结果表明了该文方法的有效性。     

MIMO Radar Using Compressive Sampling

A multiple-input multiple-output (MIMO) radar system is proposed for obtaining angle and Doppler information on potential targets. Transmitters and receivers are nodes of a small scale wireless network and are assumed to be randomly scattered on a disk. The transmit nodes transmit uncorrelated waveforms. Each receive node applies compressive sampling to the received signal to obtain a small number of samples, which the node subsequently forwards to a fusion center. Assuming that the targets are sparsely located in the angle-Doppler space, based on the samples forwarded by the receive nodes the fusion center formulates an $ell_{1}$ -optimization problem, the solution of which yields target angle and Doppler information. The proposed approach achieves the superior resolution of MIMO radar with far fewer samples than required by other approaches. This implies power savings during the communication phase between the receive nodes and the fusion center. Performance in the presence of a jammer is analyzed for the case of slowly moving targets. Issues related to forming the basis matrix that spans the angle-Doppler space, and for selecting a grid for that space are discussed. Extensive simulation results are provided to demonstrate the performance of the proposed approach at difference jammer and noise levels.      

Signal Processing for Passive Radar Using OFDM Waveforms

Passive radar is a concept where illuminators of opportunity are used in a multistatic radar setup. New digital signals, like Digital Audio/Video Broadcast (DAB/DVB), are excellent candidates for this scheme, as they are widely available, can be easily decoded to acquire the noise-free signal, and employ orthogonal frequency division multiplex (OFDM). Multicarrier transmission schemes like OFDM use block channel equalization in the frequency domain, efficiently implemented as a fast Fourier transform, and these channel estimates can directly be used to identify targets based on Fourier analysis across subsequent blocks. In this paper, we derive the exact matched filter formulation for passive radar using OFDM waveforms. We then show that the current approach using Fourier analysis across block channel estimates is equivalent to the matched filter, based on a piecewise constant assumption on the Doppler-induced phase rotation in the time domain. We next present high-resolution algorithms based on the same assumption: first we implement MUSIC as a 2-D spectral estimator using spatial smoothing; then we use the new concept of compressed sensing to identify targets. We compare the new algorithms and the current approach using numerical simulation and experimental data recorded from a DAB network in Germany.      

Improvement of EMC by Applying Ambiguity and Environmental Diagrams to the Design of Radar Waveforms

A technique for improving the electromagnetic compatibility of a radar system with respect to its operating electromagnetic environment and to assess RF spectrum usage is presented. The technique involves the use of the ambiguity diagram derived from the waveform and the construction of environinental diagrams for the radar. Overlays of the ambiguity diagram upon the environmental diagram, along desired target trajectories, provide a pictorial view by which EMC analysis and spectrum usage can be interpreted. The technique lends itself to the early phases in radar concept or development where waveform design can be modified. The technique also lends itself to assessing design towards receivèr interference rejection. Only nominal system parameter data is required for implementation.     

MIMO雷达正交混沌调频波形集设计

正交波形设计是实现MIMO雷达的关键技术之一,目前正交波形设计方法主要多采用统计优化算法,如模拟退火、遗传算法等,此类方法主要缺点是算法耗时长、效率低,且所设计的波形集性能随着波形个数的增加而下降,针对此问题,提出一种基于混沌调频的MIMO雷达正交波形集设计方法,采用混沌调频信号作为MIMO雷达的发射波形,利用混沌序列良好的统计特性,无需寻优处理即可得到性能优越的正交波形集,且理论上可以得到任意数目的波形而不损失波形集性能,因此,该方法在算法效率和波形多样性方面具有优势,计算机仿真实验验证了设计方法的有效性。      

MIMO跳频通信系统及其序列设计

在跳频通信系统中应用MIMO技术可以进一步提高数据传输速率和频谱利用率,但是多用户跳频通信系统还受到多址干扰和多径干扰的影响.本文提出一种T-NHZ时频序列的构造方法,应用到MIMO跳频系统中以消除多址干扰和多径干扰,同时由于这种序列的数目较大,有利于进一步提高系统容量.     

提高MIMO雷达估计性能的稳健波形优化设计

多输入多输出雷达的波形优化基于初始参数估计值,通常对参数估计误差较敏感。稳健波形设计通过将参数不确定性显式包含进优化问题以减轻敏感性。基于克拉美-罗界,在参数不确定凸集上考虑改善最差参数估计性能的稳健波形优化问题。提出一种优化波形相关阵的迭代算法以改善最差参数估计性能。迭代中的每步都可通过凸松弛求解。仿真表明,相对于不相关波形,所提方法可显著提高最差参数估计性能。     

最小化旁瓣的MIMO雷达发射方向图优化算法

为了获得低旁瓣的MIMO雷达发射方向图,该文提出一种新的最小化峰值旁瓣或积分旁瓣的MIMO雷达方向图优化算法.由于最小化峰值旁瓣或积分旁瓣的优化问题为非凸问题,该算法通过两步来得到此非凸优化问题的全局最优解.第1步通过对发射总功率的约束进行松弛,将原问题转变为一个凸优化问题,第2步则将第1步得到的解进行尺度变换使其满足发射总功率的约束,从而得到原问题的全局最优解.仿真实验表明了该算法相比于已有算法可以获得更低的峰值旁瓣或更低的积分旁瓣.     

基于MIMO噪声雷达的高速运动目标检测

针对传统体制雷达对高速运动目标不能进行长时间有效相参积累检测问题,该文提出了一种基于MIMO噪声雷达的高速运动目标检测方法。该方法利用MIMO噪声雷达在短时间内输出的多路回波数据进行相参并行处理来取代回波数据的长时间相参积累检测,以避免距离走动,径向速度变化以及反射截面积(RCS)快起伏等非平稳因素对目标检测的影响,有效实现了多个高速运动目标的无模糊检测。仿真结果验证了MIMO噪声雷达在高速运动目标检测方面的优越性。     

MIMO Radar Beamforming Using Orthogonal Decomposition of Correlation Matrix

MIMO radar is the next generation radar which transmits arbitrary waveforms at each one of its apertures. It has been shown that the design of waveforms for MIMO radars in order to synthesize a desired spatial beampattern is mapped into a waveform correlation matrix R design in the narrowband case. As of now, given a desired beampattern or estimated locations information of targets, calculating R has been modeled as an optimization problem like semi-definite programming. Also, in some special cases like rectangular beampattern, closed-form solutions for R has been proposed. In this paper, we introduce a fast algorithm which is capable of designing R in order to achieve more arbitrary beampatterns. Our proposed algorithm is based on eigenvalue decomposition of correlation matrix which employs neither an optimization process nor an iteration one. Furthermore, the proposed algorithm leads to uniform elemental power, low sidelobe level and targets decorrelation which is a great boon, looking from both the hardware and the software perspective. Here, we also introduce a novel algorithm which can work in tandem with the eigenvalue decomposition algorithm and other existing correlation matrix design algorithms to enhance or adapt the designed beampattern.     

双基地MIMO雷达最优化搜索参数设计研究

针对双基地MIMO雷达搜索特性,从搜索波束覆盖的几何模型出发,分析衡量波束覆盖效率的基本因素,以及其对搜索资源消耗的影响,并在此基础上提出了双基地MIMO雷达搜索波束覆盖优化的基本思路,即在不同的距离范围匹配选取不同的波束宽度和波束重叠度,从而达到快速覆盖发射波束的目的。最后建立了在约束条件限制下,同时考虑时间资源和能量资源消耗的搜索优化模型,仿真分析了影响搜索资源消耗参数(脉冲重复个数、脉冲宽度、搜索周期)的最优值随检测概率门限值的变化规律,为最优化搜索参数选取提供依据。     

基于联合矩阵对角化的双基地MIMO雷达DOD-DOA估计

针对双基地MIMO雷达收发角(DOD-DOA)估计问题,该文提出一种基于联合矩阵对角化的快速多目标收发角估计算法.该算法首先根据匹配滤波输出的数据结构,利用奇异值分解和秩1矩阵判断定理将收发角度估计问题转化为联合矩阵对角化问题,然后采用单次-扫描迭代算法对其求解,得到收发阵列流型矩阵,最后通过谱分析方法估计收发角.该算法充分利用匹配滤波输出的所有信息,无需2维谱峰搜索,每次迭代均可得到精确的闭式解,且收发角自动配对.与现有算法相比,该算法不仅提高了角度估计精度,而且有效降低了运算量.仿真结果证明了所提算法的有效性.     

基于协方差矩阵的MIMO雷达离散编码设计

MIMO雷达相对于传统的相控阵雷达,可以更自由地选择发射波形来匹配所需要的发射方向图。文中首先给出了一个带有限制条件的优化问题以寻找发射信号的协方差矩阵,从而能够在空间匹配理想的方向图,接着建立了一组恒模的二相离散序列来匹配已有的协方差矩阵,并将这种方法推广到多相码设计中,并对实验结果进行了详细分析。     

基于改进自适应遗传算法的MIMO 雷达阵列优化

针对传统遗传算法在全局搜索和收敛方面的不足,提出一种改进自适应遗传算法.算法改进了自适应规则,采用随迭代次数和种群适应度自适应变化的交叉、变异操作,同时采用新的选择算子和改进后的最优精英保留策略,摒弃了传统轮盘赌博选择法,增加了收敛于全局最优解的概率,加快了收敛速度.通过测试函数优化求解试验证明,改进算法能够有效提高搜索过程种群的多样性,具有更快的收敛性和更好的全局最优性.在此基础上,将改进的自适应遗传算法应用到MIMO雷达阵列优化设计,通过稀疏栅格编码,采用同时考虑副瓣电平与波束宽度的双适应函数,使优化得到的MIMO雷达方向图具有更好的综合性能,更利于实际工程应用.最后仿真实验结果进一步验证了本文改进算法的有效性.     

A New Iterative Approach in SINR Improvement of MIMO Radars by Using Combination of Orthogonal Waveforms

Wireless Personal Communications - In this paper we consider joint waveform and filter design in multi-input multi-output (MIMO) radars in the presence of signal dependent interference to improve...     

MIMO Radar Waveform Optimization With Prior Information of the Extended Target and Clutter

The concept of multiple-input multiple-output (MIMO) radar allows each transmitting antenna element to transmit an arbitrary waveform. This provides extra degrees of freedom compared to the traditional transmit beamforming approach. It has been shown in the recent literature that MIMO radar systems have many advantages. In this paper, we consider the joint optimization of waveforms and receiving filters in the MIMO radar for the case of extended target in clutter. A novel iterative algorithm is proposed to optimize the waveforms and receiving filters such that the detection performance can be maximized. The corresponding iterative algorithms are also developed for the case where only the statistics or the uncertainty set of the target impulse response is available. These algorithms guarantee that the SINR performance improves in each iteration step. Numerical results show that the proposed methods have better SINR performance than existing design methods.      

基于差分粒子群优化的MIMO雷达阵列综合

提出一种基于差分粒子群优化算法(Differential Particle Swarm Optimization, DPSO)的MIMO 雷达方向图综合方法,通过发射、接收阵元位置和激励幅度的联合优化,可实现MIMO 雷达方向图旁瓣电平与零陷深度的联合控制。在粒子位置和速度更新机制的基础上,引入差分进化(Differential Evolution, DE)思想而设计的交叉、变异和位置扰动策略以保持种群在迭代后期的搜索多样性,从而改善算法的全局寻优性能。数值实验结果验证了所提方法的有效性以及相对其他算法的性能优势。     

Constrained Waveform Designing for MIMO RADAR Using Jaya Optimization

Wireless Personal Communications - Multiple Input Multiple Output RADAR system is proficient in forming desired beampattern by designing transmit waveforms. In this paper, Poly Phase coded...