摘要
MIMO雷达是近年来迅速发展的一种新体制雷达技术,其在发射端同时发射正交信号,在接收端通过匹配滤波恢复发射信号分量。由于MIMO雷达同时采用了空间分集和信号分集技术,所以它表现出许多不同于传统雷达的性能。
本文先建立了一个简单的MIMO雷达信号模型。在讨论了几种自适应准则和自适应波束形成算法的基础上,探讨了MIMO雷达系统中适用的自适应波束形成算法。在MIMO雷达系统中,由于有杂波和干扰的存在,传统的自适应波束形成算法已不能准确地估计出目标的方向,因此采用了Capon算法、APES算法、CAPES算法和CAML等算法。在有噪声和干扰的情况下,Capon算法能有效地估计目标的方向；APES算法能精确地估计目标的幅度；结合了两者优点的CAPES算法以及由Capon和AML结合的CAML算法对目标的方向和幅度估计十分精确。对于仅有高斯噪声的情况,采用了最大似然估计方法比较了MIMO雷达和相控阵雷达对波达方向的估计,证实MIMO雷达具有更优的性能。
MIMO雷达的显著特性能使得其在GMTI雷达中的应用显得至关重要。简单分析了MIMO GMTI雷达系统中的一些性能参数：波形的优化、信噪比损耗以及最小检测速度等。对于存在高斯噪声和杂波环境下的目标,当信噪比超过一个阈值时,MIMO雷达比相控阵雷达有更高的目标检测概率。针对杂波环境中的非起伏目标,MIMO雷达经过GMTI处理之后,对以任意角度运动的目标均可获得较高的改善因子。
MIMO radar is a new radar technique developed quickly in the recent years.On transmitting, each channel radiates a orthogonal coded waveform. On receiving, the return signals are processed through a bank of matched filters to separate each transmitted signal. Because of the application of the space diversity and the signal diversity techniques, the performances of MIMO radar have many differences from the conventional radars.
First, we model the MIMO radar signal.In the base of the several kinds of adaptive criterion and adaptive beamforming algorithm, we discuss the adaptive beamforming algorithm that can be used in the MIMO radar system. As to the presence of strong interference and jamming in the MIMO radar system, we propose several algorithms that can effectively ignore the interference and jamming:Capon, APES,CAPES and CAML. In the presence of strong interference and jamming:Capon can effectively tell the direction of the target; APES can tell the exact amplitude of the target; the combination of Capon and APES-CAPES and the combination of Capon and AML- CAML can tell the exact direction and amplitude of the targets. As to the presence of the Gauss noise, we use the ML method to compare the estimation of DOA in MIMO radar and phased array radar, and after a series of experiment, we prove that MIMO radar has the better performance.
Ground moving-target indicator (GMTI) radar offers a potentially important application for MIMO radar technique. We discuss the performance of MIMO GMTI radars.Simple characterizations of performance are introduced. We investigate waveform correlation optimization. A significant issue is the minimum detectable velocity. As to the target in the presence of the Gauss noise and clutters, when SNR is larger than a threshold, MIMO radar has the better detectable performance than phased array radar. As to the non-fluctuation targets in the clutters, MIMO radar can acquire higher improvement factor to targets moving at arbitrarily angle after the processing of GMTI.
引文
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