Moving Target Imaging for TDM MIMO Radar via an Angle-Doppler Spectrum Restoration Approach

Time-Division Multiplexing (TDM) MIMO radar has attracted significant attention due to its hardware simplicity. However, its applications are significantly limited by two main challenges: motion-induced phase migration and the low-PRF characteristic. Accurate velocity estimation, which is required to compensate for motion-induced phase migration, cannot be achieved using the conventional range-Doppler process due to the low PRF. To address this issue, we propose a novel method based on the angle-phase-compensated angle-Doppler spectrum (APAD). We demonstrate that the APAD spectrum is essentially the ideal angle-Doppler spectrum blurred by a point spread function (PSF), which is determined by the system parameters of the TDM MIMO radar. By applying L1 regularization and the Alternating Direction Method of Multipliers (ADMM), the deblurring process can restore the angle-Doppler spectrum, enabling unambiguous velocity estimation and undistorted direction-of-arrival (DOA) detection. Furthermore, we analyze the Cramer-Rao Bound (CRB) of the proposed method and compare it with a single-cycle method. Through extensive simulations, we demonstrate that the proposed method outperforms existing methods in terms of radar imaging and velocity estimation. Finally, we validate the effectiveness of the proposed method in complex scenarios through real-world experiments.