This study proposes an advanced direction-of-arrival (DOA) estimation method for automotive multiple-input multiple-output (MIMO) fast-ramp radar systems. To distinguish the transmitted signal at the receiving antenna, the orthogonal code can be applied to each transmitted signal. In this case, to correctly estimate the angles of the targets, the authors also have to match the distinguished signals to each transmit antenna element. In this study, they use the space-time block code to distinguish the transmitted signals from the receiving antennas. Furthermore, by applying the deterministic maximum likelihood algorithm to each of the distinguished signals, they can find the true antenna array for DOA estimation and achieve higher estimation accuracy than false antenna array cases. Furthermore, the maximum detectable velocity is doubled compared to the conventional decoding method. In the simulation results, the proposed method provides a three degree smaller root-mean-squared error compared to the case when it is not applied. The proposed method also estimates the DOAs of the targets well at low signal-to-noise ratios. In addition, the effectiveness of the proposed method was verified by measurement results.

中文翻译：

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通过区分汽车MIMO调频连续波雷达系统中不同发射信号的改进DOA估计方法

这项研究提出了一种先进的到达方向（DOA）估计方法，用于汽车多输入多输出（MIMO）快速匝道雷达系统。为了区分接收天线处的发射信号，可以将正交码应用于每个发射信号。在这种情况下，为了正确估计目标的角度，作者还必须将识别信号匹配到每个发射天线元件。在这项研究中，他们使用时空分组码来区分发射信号和接收天线。此外，通过将确定性最大似然算法应用于每个区分的信号，他们可以找到用于DOA估计的真实天线阵列，并获得比错误天线阵列情况更高的估计精度。此外，与传统解码方法相比，最大可检测速度提高了一倍。在仿真结果中，与未应用该方法相比，该方法提供的均方根误差小三度。所提出的方法还可以在低信噪比的情况下很好地估计目标的DOA。另外，通过测量结果验证了该方法的有效性。