An Interference Mitigation Technique for FMCW Radar Using Beat-Frequencies Interpolation in the STFT Domain

Abstract

A frequency-modulated continuous-wave (FMCW) radar interference mitigation technique using the interpolation of beat frequencies in the short-time Fourier transform (STFT) domain, phase matching, and reconfigurable linear prediction coefficients estimation for Coherent Processing Interval processing is proposed. The technique is noniterative and does not rely on algorithm convergence. It allows the usage of the fast Fourier transform (FFT) as the radar's beat-frequency estimation tool, for reasons such as real-time implementation, noise linearity after the FFT, and compatibility with legacy receiver architectures. Verification is done in range and in range-Doppler using radar experimental data in two ways: first by removing interferences from interference-contaminated data and second by using interference-free data as the reference data, and processing it-as if it had interferences-using the proposed technique, inverse cosine windowing and zeroing for comparison. We found that processing with the proposed technique closely matches the reference-data and outperforms the inverse cosine windowing and zeroing techniques in 2-D cross correlation, amplitude, and phase average errors and phase root-mean-square error. It is expected that the proposed technique will be operationally deployed on the TU Delft simultaneous-polarimetric PARSAX radar. Index Terms-Frequency-modulated continuous wave (FMCW), linear prediction (LP), multiple-input and multipleoutput radars, polarimetric radars, radar interference mitigation techniques. I. INTRODUCTION F REQUENCY-modulated continuous-wave (FMCW) radars might suffer from interferences from other radars operating within their vicinity, as in multiple-input and multiple-output radar networks and in automotive scenarios, or from themselves as in the case of fully polarimetric radars with dual-orthogonal signals [1], where there is a leakage between two mutually orthogonal channels (cross-channel interference). In deramp FMCW radars (stretch-processing), targets' range is deduced from beat-frequency estimation. Processing interference-contaminated beat frequencies with fast Fourier transforms (FFTs) yields poorer radar detection, due to undesired artifacts such as a noise-floor level increase in range

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