Adaptive detection with conic rejection to suppress deceptive jamming for frequency diverse MIMO radar

With traditional radar systems, it is not easy to classify and suppress the intended false targets, especially in case of the mainlobe deceptive jamming. In this paper, the deceptive jamming suppression issue is formulated as a problem of detecting the presence of target signal while rejecting potential deceptive jamming under the multiple-input multiple-output (MIMO) radar with frequency diverse array (FDA) as the transmit array. The problem at hand is settled by resorting to the generalized likelihood ratio test (GLRT); at the design stage we define the sets where the false target and true target lie in. Since FDA-MIMO radar provides controllable degrees of freedom in both range and angle domains, the sets are range–angle related. This implies that both range and angle properties can be used to suppress the false targets. Based on the detector, a two-pulse scheme is proposed to guarantee high rejection probability of deceptive jamming. At the analysis stage, the performance of the detector is assessed in comparison with the conventional MIMO scenario and other detectors. The performance assessment shows that the proposed solutions are effective in the presence of electronic countermeasure (ECM) systems, especially when facing mainlobe deceptive jamming.     

Joint direction of arrival estimation and array calibration for coprime MIMO radar

Compared to large-scale MIMO radar, coprime MIMO radar can achieve approximate estimation performance with reduced antenna number. In this paper, joint direction of arrival (DOA) estimation and array calibration for coprime multiple-input multiple-output (MIMO) radar is considered, and an iterative method for the estimations of DOA and array gain-phase errors is proposed. Based on the received data structure of coprime MIMO radar, trilinear decomposition is firstly adopted to obtain the estimations of transmit and receive direction matrices, which are perturbated by the gain-phase errors. Through equation transformation, the un-perturbated direction matrices and gain-phase errors can be iteratively updated based on Least squares (LS). Finally, the unique DOA estimation is determined from the intersection of transmit and receive direction matrices. The proposed algorithm achieves better DOA estimation and array calibration performance than other methods including estimation of signal parameters via rotational invariance techniques (ESPRIT)-like algorithm, multiple signal classification (MUSIC)-like algorithm and joint angle and array gain-phase error estimation (JAAGE) method, and it performs close to the method with ideal arrays. Multiple simulation results verify the algorithmic effectiveness of the proposed method.     

一种4D毫米波雷达高分辨角度估计方法

针对4D毫米波雷达中雷达孔径受限导致的角度分辨率不高的问题,提出一种改进的多重信号分类(Multiple Signal Classification,MUSIC)算法。首先通过数据预处理手段,补偿多输入输出(Multiple Input Multiple Output,MIMO)虚拟阵列中目标运动引起的相位误差;接着划分子阵并对角度维数据构成的协方差矩阵进行Toeplitz化处理,利用MUSIC算法估计一维角度;最后采用特征值排序的方法将估计出的俯仰角与方位角进行快速配对。该方法有效提高了4D毫米波雷达角度维估计的分辨率和估计精度,也提高了二维角度估计的计算速度。数值仿真与实物实验验证了所提方法在角度高分辨估计上的性能。     

基于MUSIC谱估计的探地雷达回波处理方法

为了克服现有信号处理算法对探地雷达噪声及杂波滤除的不足,提出了一种基于MUSIC谱估计时域与频域联合滤波方法。利用常用的去直流波和均值滤波抑制方法进行雷达信号预处理,在此基础上,引入谱分析中信号子空间与噪声子空间的概念,将MUSIC算法与最小二乘法相结合来进行探地雷达杂波及噪声处理。仿真及实验结果表明,提出的回波处理方法可以有效地抑制雷达信号中的噪声和杂波,能提高测量数据的精度,具有较高的实用性和可用性。     

色噪声环境下双基地MIMO雷达相干目标角度估计算法

通过研究多输入多输出(Multiple input and multiple out,MIMO)雷达的角度估计算法,针对色噪声环境下双基地MIMO雷达相干目标角度估计问题,基于双基地MIMO雷达的信号模型,利用MIMO雷达的接收数据,通过四阶累积量的计算消除了色噪声的影响,并证明得到的一组矢量包含所有目标的角度信息;然后利用得到的四阶累积量矢量构造出块Hankel矩阵,并证明该矩阵的秩等于目标总数,且不受信号相干性的影响,通过奇异值分解,结合ESPRIT算法实现了色噪声环境下对相干目标的角度估计.算法结合四阶累积量和MIMO雷达的估计性能,具有自动抑制加性高斯白噪声和色噪声的能力,实现了相干目标的有效估计和参数的自动配对,提高了抗噪能力,更利于在实际中应用.最后计算机仿真结果证实了算法的有效性和可行性.     

基于四元数和增广矩阵束的MIMO雷达角度估计算法

通过研究多输入多输出（Multiple input and multiple out, MIMO）雷达的角度估计算法,基于收发共址的十字阵MIMO雷达系统,将四元数理论应用到 MIMO雷达角度中,提出了一种新的参数估计算法。通过构造四元数模型,结合增广矩阵束（ Matrix enhancement and matrix pencil, MEMP）方法构造增广矩阵,并证明该矩阵的秩 等于目标总数,且不受目标相干性的影响,结合ESPRIT算法实现了对MIMO相干目标的角度估 计。算法无需谱峰搜索,能够实现参数的自动配对,同时降低了运算复杂度。仿真实验进一 步验证了算法的有效性。     

基于SystemVue汽车雷达系统研究

针对毫米波雷达射频、信号处理以及超分辨测角问题,提出了一种基于SystemVue进行汽车雷达系统设计和信号处理算法设计的方法。首先,利用SystemVue自带的射频库和通用算法库进行雷达系统设计,真实模拟了毫米波射频、天线及目标环境的相互影响;其次,针对快调频的FMCW信号波形,给出了完整的汽车雷达目标距离、速度和角度的信息处理算法流程;最后,针对汽车雷达系统测角精度较低的问题,提出了基于酉变换MUSIC的测角算法,大大降低了汽车雷达超分辨求角的运算量。仿真结果表明,该方法解决了汽车雷达的链路设计、射频指标对雷达信号处理性能影响的评估问题,更真实、更全面地反映了汽车雷达系统的性能,为雷达系统的研究提供了有力依据。     

Estimation of CFO and STO for an OFDM using general ICI self-cancellation precoding

This study presents an efficient carrier-frequency-offset (CFO) and symbol-timing-offset (STO) estimation algorithm for time-dispersive orthogonal frequency division multiplexing (OFDM) system using a general inter-carrier interference (ICI) self-cancellation scheme. This study takes advantage of the time shift invariant property in the precoded signal to estimate the CFO. The proposed algorithm first stacks the receive time samples spaced by a pre-determined time interval into sample vectors, which can be expressed in a form having a CFO-directed response vector. This CFO-directed structure enables the proposed approach to estimate the CFO by using the multiple signal classification (MUSIC) algorithm in the time domain. Equalization is required before the MUSIC algorithm to remove the scaling factor generated in the signal stacking. Using the CFO estimate, the proposed approach compensates for the frequency error in the receive signal and then estimates the STO by invoking the MUSIC algorithm in the frequency domain. Unlike conventional algorithms, in addition to having a larger CFO estimation range linearly proportional to the precoding order, the proposed approach can easily handle the case of fractional STO. This study presents some statistical analysis of the undesired equalization residues and the mean square error of the perturbed MUSIC algorithm to provide further insights into the proposed approach.     

A sparse direction-of-arrival estimation algorithm for MIMO radar in the presence of gain-phase errors

In this paper, the problem of direction-of-arrival (DOA) estimation for monostatic multiple-input multiple-output (MIMO) radar with gain-phase errors is addressed, by using a sparse DOA estimation algorithm with fourth-order cumulants (FOC) based error matrix estimation. Useful cumulants are designed and extracted to estimate the gain and the phase errors in the transmit array and the receive array, thus a reliable error matrix is obtained. Then the proposed algorithm reduces the gain-phase error matrix to a low dimensional one. Finally, with the updated gain-phase error matrix, the FOC-based reweighted sparse representation framework is introduced to achieve accurate DOA estimation. Thanks to the fourth-order cumulants based gain-phase error matrix estimation, and the reweighted sparse representation framework, the proposed algorithm performs well for both white and colored Gaussian noises, and provides higher angular resolution and better angle estimation performance than reduced-dimension MUSIC (RD-MUSIC), adaptive sparse representation (adaptive-SR) and ESPRIT-based algorithms. Simulation results verify the effectiveness and advantages of the proposed method.     

Two-dimensional angle estimation for monostatic MIMO arbitrary array with velocity receive sensors and unknown locations

In this paper, the problem of two-dimensional angle estimation for monostatic multi-input multi-output (MIMO) array is studied, and an algorithm based on the usage of velocity receive sensors is proposed. The algorithm applies the estimation method of signal parameters via rotational invariance technique (ESPRIT) algorithm to obtain automatically paired two-dimensional angle estimation. By utilizing the relationship within the outputs of velocity sensors, the rotational invariance property of ESPRIT does not depend on the array geometry any more. Hence, the proposed algorithm can provide two-dimensional DOA estimation for the MIMO array without the knowledge of sensor locations in the array. The algorithm requires no peak searches, so it has low complexity. Furthermore, it has better angle estimation performance than propagator method using the same sensor configuration. Error analysis and Cramér–Rao bound (CRB) of angle estimation in MIMO radar are derived. Simulation results verify the usefulness of the algorithm.     

十字阵的单基地MIMO雷达中一种低复杂度的二维DOA估计算法

提出了在单基地多输入多输出(Multiple-input multiple-output,MIMO)雷达中的基于十字阵的一种低复杂度的二维波达方向(Direction of arrival,DOA)估计算法。该算法利用传播算子法(Propagator method,PM)避免了协方差矩阵的构造及其特征值分解,也无需谱峰搜索,从而大大降低了运算的复杂度;同时该算法可实现方位角和仰角的自动配对。本文算法的性能在高信噪比下逼近借助旋转不变技术估计信号参数(Estimation ofsignal parameters via rotational invariance techniques,ESPRIT)算法。文中还推导了目标方位角和仰角的均方误差。仿真结果证明了该算法的有效性。     

基于Stackelberg博弈的多输入多输出雷达信号与目标干扰优化

针对实际杂波环境中多输入多输出(MIMO)雷达与目标间检测与隐身的博弈问题,提出一种新的两步注水算法。首先建立时空编码模型;然后基于互信息量准则,用注水法分配目标干扰功率,用通用注水法分配雷达信号功率;最终得到强弱杂波环境Stackelberg博弈中目标占优和雷达占优的优化方案。仿真结果表明,雷达信号功率分配和通用注水水位变化规律均受杂波影响,两优化方案的互信息量在强杂波环境降低约50%,干扰影响系数分别降低0.2和0.25,互信息量受干扰影响程度降低,证明了所提算法的有效性。     

MIMO SAR OFDM chirp waveform design and GMTI with RPCA based method

Multiple-input multiple-output synthetic aperture radar (MIMO SAR) has drawn wide attention for its increased degrees of freedom (DOFs) compared to the traditional multi-channel SAR (MC-SAR) system. The MIMO SAR system, which makes each antenna illuminate one subswath, can widen the range swath without decreasing PRF. One of the foremost tasks involved in the MIMO SAR system is the waveform design at the transmitter. Moreover, at the receiver, how to accurately separate the auto-correlation signal from the cross-correlation interferences is the other important issue. In this paper, an orthogonal frequency division multiplexing (OFDM) chirp signal designing method is firstly proposed, which is based on low cross-correlation interferences and good peak-to-sidelobe ratio (PSLR) rules. Using the designed OFDM chirp signals, the focused signal of MIMO SAR system matched the robust principal component analysis (RPCA) basic model. The moving target (sparse signal), clutter (low-rank signal) and noise (noise signal) can be separated directly. Hence, RPCA based method can be employed for ground moving target indication (GMTI) with no need for extracting the matched signal or suppressing the unmatched interferences. Extensive simulations demonstrate the effectiveness of the waveform designing method and GMTI with RPCA based method for MIMO SAR system.     

双基地MIMO雷达中基于传播算子的DOD和DOA估计算法

多输入多输出(Multiple-input multiple-output,MIMO)雷达利用多个天线发送和接收信号,具有超过传统相控阵的潜在优势.本文提出一种双基地MIMO雷达中基于传播算子的离开角(Direction of departure,DOD)和到达角(Direction of arrival,DOA)估计...     

Range‐angle target indication using FDA‐MIMO with sinusoidal element spacing

By introducing a tiny frequency increment across the array elements, frequency diverse array (FDA) radar produces a range‐angle‐dependent beampattern. However, the range‐angle coupling and time‐variant problem block the application potential of the conventional FDA. Employing sinusoidal element spacing and symmetrical sinusoidal modulated frequency offsets, a novel scheme termed as Sin‐FDA is proposed. To eliminate the time‐varying effect, multiple‐input multiple‐output technique and multiple matched filters at receiver are adopted. The proposed scheme can generate a pencil‐shaped beampattern with smaller spatial region of mainlobe in range‐angle domains, which is helpful for improving the target indication performance. Furthermore, the beampattern produced by the proposed scheme has narrower mainlobe both in the range and angle dimensions as well as acceptable sidelobe level. The exploration of nonuniform element spacing can better direct the range‐angle decoupled beampattern design for FDA radar. Simulation results validate the superiority of the proposed scheme over the existing decoupled FDA systems.     

Quaternion-MUSIC for near-field strictly noncircular sources with large-scale polarization array

In this paper, a novel localization method is proposed for DOA, range and polarization estimation of near-field noncircular sources in massive multiple-input-multiple-output (MIMO) systems. Compared with traditional MUSIC-based algorithms, the proposed algorithms can separate the polarization parameters from the spatial spectrum function, avoiding the four-dimensional (4-D) spectrum search and realizing the fast localization of the near-field source with high accuracy. First, the dimension-reduced MUSIC (DR-MUSIC) algorithm is proposed for DOA and range estimation with low computational complexity, and given a closed-form expression of polarization estimation. Next, based on the quaternion theory, a novel algorithm named quaternion non-circular MUSIC (QNC-MUSIC) is proposed for parameter estimation of non-circular signals with high estimation accuracy. In addition, the analysis of the computational complexity and simulations of the proposed method are provided, showing that the proposed method yields a better performance than DR-MUSIC in massive MIMO systems.     

杂波背景MIMO雷达与目标博弈时优化策略研究

针对杂波背景多输入多输出(MIMO)雷达与目标博弈问题,从最小均方误差(MMSE)估计角度提出两种可行的雷达波形设计优化策略,结合两步注水算法得到不同策略下的博弈方案。基于Stackelberg均衡模型,博弈方案用注水法分配目标干扰功率,用通用注水法分配雷达信号功率。仿真比较了杂波背景两种优化策略下雷达先行的博弈方案,结果表明优化策略二得到的MMSE值更小,证明了优化策略二的有效性,但雷达信号和目标干扰总功率均较小时,优化策略二反而不如优化策略一,对雷达正确选择优化策略以赢得与目标的博弈有一定借鉴意义。     

MUSIC算法的FPGA实现

针对多重信号分类（MUSIC）算法计算复杂度高,难以实时实现的特点,给出了适用于均匀线阵的实数化预处理算法和实用的空间谱定义,并选择了适合FPGA硬件实现的特征值分解算法,给出了MUSIC算法FPGA实现的整体架构。仿真实验结果表明,该FPGA实现能够完成MUSIC算法的准确、快速计算。     

Deceptive jamming discrimination based on range-angle localization of a frequency diverse array

We propose a method to suppress deceptive jamming by frequency diverse array (FDA) in radar electronic countermeasure environments. FDA offers a new range-angle-dependent beam pattern through a small frequency increment across elements. Due to the coupling between the angle and range, a mismatch between the test angle and physical angle occurs when the slant range on which the beam focuses is not equal to the slant range of the real target. In addition, the range of the target can be extracted by sum-difference beam except for time-delay testing, because the beam provides a range resolution in the FDA that cannot be deceived by traditional deceptive jamming. A strategy of using FDA to transmit two pulses with zero and nonzero frequency increments, respectively, is proposed to ensure that the angle of a target can be obtained by FDA. Moreover, the localization performance is examined by analyzing the Cramer-Rao lower bound and detection probability. Effectiveness of the proposed method is confirmed by simulation results.     

Analysis of optimized signal processing algorithms for smart antenna system

By the exponential increase in cellular communication area, the user demands and with their side problems also tend to increase. Several techniques such as cell splitting, frequency reuse, diversity and so on have already been applied to overcome these problems. In all these procedures, smart antenna is one of the best techniques used to boost capacities, enlarge bandwidth, raise the SIR ratios, minimize the effects of fading and improve MIMO communications. An ordinary antenna array which can turn up into a smart antenna array is due to the signal processing algorithms, which consists of angle of arrival (AOA) estimations and Beamforming. In this paper, I will discuss and analyse about the MUSIC algorithm for AOA estimation and least mean squares algorithm for Beamforming.