Real-Time Interference Mitigation in Automotive Radars Using the Short-Time Fourier Transform and L-Statistics

The growing use of FMCW radars in automotive vehicles has led to the occurrence of mutual interference between radar sensors. Efforts to mitigate this phenomenon are crucial for ensuring the reliable operation of radar systems in complex vehicular environments. In the majority of the proposed mitigation approaches, real-time implementations are notably absent, and many of these methods are usually evaluated by post processing utilizing synthetic or real-world data. This article presents a real-time method for mitigating uncorrelated automotive interferences using the Short Time Fourier Transform (STFT) and L-Statistics. The idea of the method is to compute the STFT of the beat signal and sort each constant frequency line of the spectrogram in ascending order, which places the bins affected by interference towards the right hand side of the time-frequency plane. Onwards, the interference-free range profile is computed by a coherent summation along the time axis of the bins considered to be unaffected by interference (the first $q\%$ of time bins from the sorted spectrogram). In the development steps of the method, synthetic automotive radar signals were used to evaluate the impact of various design parameters (e.g., sliding window length and step size of the STFT, and the summation percentage $q\%$ ) on the performance. Notably, this algorithm does not require a prior interference detection step and by choosing the STFT step size to half of the window length it demonstrates almost performance parity with the unitary step size case, affording a reduction in computation time and facilitating real-time implementation. The method was successfully implemented on a Texas Instruments AWR1843 radar platform and tested within a controlled laboratory environment. The real-time processing flow is presented in detail with an emphasis on the implementation particularities related to the hardware resources of the AWR1843 platform. The tests encompassed various scenarios where the AWR1843 was used like victim radar and up to three additional similar radar platforms used as interference sources with different parameters.