Frequency-diverse array multiple-input–multiple-output (FDA-MIMO) radar differs from the traditional phased array (PA) radar, and can form range-angle-dependent beampattern and differentiate between closely spaced targets sharing the same angle but occupying distinct range cells. In the FDA-MIMO radar, target range estimation is achieved by employing a subtle frequency variation between adjacent array antennas, so the estimation performance is degraded severely in a practical scenario with frequency offset. In this article, the range-angle estimation problem for the FDA-MIMO radar is considered with frequency offsets in both transmitting and receiving arrays. First, we build a system model for the FDA-MIMO radar with transmitting and receiving frequency offsets. Then, the frequency offset is transferred into an equalized additional noise. The noise characteristics are analyzed in detail theoretically, together with the influence on the range-angle estimation. Moreover, since the effect of the transmitting frequency offset is similar to additional colored noise, denoising algorithms are introduced to mitigate the performance deterioration caused by the frequency offset. Finally, Cramér–Rao lower bounds for the range-angle estimation are derived in the scenario with the frequency offsets. Simulation results show the analysis of frequency offset and the corresponding estimation performance using different algorithms.

中文翻译：

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具有频率偏移的 FDA-MIMO 系统的距离-角度估计


频分集多输入多输出（FDA-MIMO）雷达与传统相控阵（PA）雷达不同，可以形成距离角度相关的波束图，并区分具有相同角度但占据不同位置的近距离目标范围单元格。在FDA-MIMO雷达中，目标距离估计是通过相邻阵列天线之间细微的频率变化来实现的，因此在存在频率偏移的实际场景中估计性能会严重下降。在本文中，FDA-MIMO 雷达的距离角估计问题考虑了发射和接收阵列中的频率偏移。首先，我们建立了具有发射和接收频率偏移的 FDA-MIMO 雷达的系统模型。然后，频率偏移被转换成均衡的附加噪声。从理论上详细分析了噪声特性以及对距离角估计的影响。此外，由于发射频率偏移的影响类似于附加有色噪声，因此引入降噪算法来减轻频率偏移引起的性能恶化。最后，在具有频率偏移的情况下导出距离角估计的 Cramér–Rao 下界。仿真结果显示了频率偏移的分析以及使用不同算法的相应估计性能。