Waveform design is a significant topic in multiple-input-multiple-output (MIMO) radar. In this paper, we address the problem of waveform design for colocated narrowband MIMO radar transmit beampattern synthesis. The existing methods have not comprehensively considered the transmit beampattern synthesis under multiple practical constraints, such as constant modulus constraint, Doppler tolerance, high range resolution and low auto-correlation sidelobe. We consider these practical constraints and propose a novel chirp rate diversity-based linear frequency modulated (CRD-LFM) waveform design for approximating the desired MIMO radar transmit beampattern. To tackle the problem, we improve the classical two-step approach. Firstly we design the covariance matrix using the existing closed-form solution. Then we model the problem of obtaining the waveforms from the covariance matrix as a nonlinear optimization problem, and we utilize the Sequential Quadratic Programming (SQP) algorithm to solve it. The simulations demonstrate that the waveforms obtained by this method can well approximate the desired transmit beampattern and have higher range resolution. Furthermore, we verify that the suppression of auto-correlation sidelobe can be achieved using amplitude weighting, which is easily realizable in practical engineering.

中文翻译：

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基于线性调频速率分集的MIMO雷达部分相关波形设计

波形设计是多输入多输出（MIMO）雷达中的一个重要课题。在本文中，我们解决了共置窄带 MIMO 雷达发射波束方向图合成的波形设计问题。现有方法没有全面考虑恒模约束、多普勒容限、高距离分辨率和低自相关旁瓣等多种实际约束下的发射波束方向图合成。我们考虑了这些实际限制，并提出了一种新颖的基于线性调频频率分集的线性调频 (CRD-LFM) 波形设计，用于近似所需的 MIMO 雷达发射波束图。为了解决这个问题，我们改进了经典的两步方法。首先，我们使用现有的封闭式解来设计协方差矩阵。然后我们将从协方差矩阵获取波形的问题建模为非线性优化问题，并利用顺序二次规划（SQP）算法来解决它。仿真结果表明，该方法获得的波形能够很好地逼近期望的发射波束方向图，并且具有较高的距离分辨率。此外，我们验证了可以使用幅度加权来实现自相关旁瓣的抑制，这在实际工程中很容易实现。