Automotive FMCW Radar With Difference Co-Chirps

In an automotive radar scenario, the transmission of sparsely spaced chirps along slow time creates opportunities to significantly reduce or completely avoid mutual interference. However, nonuniform chirps result in high Doppler sidelobes, which may introduce ambiguity in Doppler estimation. In this article, we present an automotive frequency-modulated continuous-wave radar that exploits difference co-chirps to achieve high-accuracy range–Doppler estimation with low complexity. By exploiting sparsity in slow time, the proposed method achieves the same Doppler velocity resolution as the regular uniform pulsing but with much fewer chirps. The silent transmission intervals become available to other automotive radars, thereby eliminating the mutual interference. The fast-time samples are treated as snapshots to construct the second-order statistical information for Doppler spectrum estimation. For our proposed nonuniform pulsing, we develop an efficient range–Doppler spectrum estimation method and propose a matching technique that is based on 2-D compressed sensing followed by Doppler dealiasing. This algorithm achieves ipso facto range–Doppler pairing without grid mismatch errors in parameter estimation and does not require an exhaustive search. Extensive numerical experiments show that accurate range–Doppler estimation is achieved with significantly fewer chirps compared to the conventional consecutive transmission. Field campaigns using Texas Instruments imaging radar support our theoretical investigations.