Interference Mitigation for FMCW Radar Based on Filtering in Fractional Fourier Domain

In this article, we explore interference mitigation (IM) techniques for frequency-modulated continuous-wave (FMCW) radar by employing filtering in the fractional Fourier transform (FrFT) domain. The suggested approach capitalizes on the observation that the acquired beat signal of the FMCW radar consists of multiple individual tones, while the interference manifests as brief chirped pulses. By leveraging the aggregation of the chirp signal in the FrFT domain with the corresponding order, the interferences are identified through a constant false alarm rate detector along the fractional frequency axis and alleviated by reconfiguring the FrFT spectrum. Furthermore, an iterative algorithm is formulated based on the golden section search to diminish the computational load of the search process for the corresponding order. The effectiveness of our approach is validated through simulated and measured data. The findings suggest that our IM approach is effective even in scenarios where the input signal-to-interference-plus-noise ratio is below $-$23 dB.