Mixed-Field Localization for Range-Angle Migration with Low Complexity in Automotive MIMO Radar Systems

In this paper, we present a direction of arrival (DOA) estimation method for multiple-input and multiple-output frequency-modulated continuous wave radar systems considering range-angle migration and piecewise sub-array model. In general, DOA estimation methods based on an exact wavefront model can achieve highly accurate results. However, the methods also entail considerable computational complexity, hindering real-time radar data processing in automotive driving. To reduce the computational complexity caused from the nonlinearity of wavefront curvature, we use a piecewise sub-array model and FFT-based methods in both the range and angle domains. The proposed method combines the advantages of far-field-based methods and near-field-based methods, thereby offering enhanced resolution at a reduced computational cost. We confirm that the DOA spectrum generated by the proposed method achieves higher resolution compared to conventional far-field-based methods and demonstrates approximately four times greater computational efficiency (in terms of FLOPs) than the back-projection algorithm.