Designing Interference-Immune Doppler-TolerantWaveforms for Automotive Radar Applications

Dynamic target detection using FMCW waveform is challenging in the presence of interference for different radar applications. Degradation in SNR is irreparable and interference is difficult to mitigate in time and frequency domain. In this paper, a waveform design problem is addressed using the Majorization-Minimization (MM) framework by considering PSL/ISL cost functions, resulting in a code sequence with Doppler-tolerance characteristics of an FMCW waveform and interference immune characteristics of a tailored PMCW waveform (unique phase code + minimal ISL/PSL). The optimal design sequences possess polynomial phase behavior of degree Q amongst its sub-sequences and obtain optimal ISL and PSL solutions with guaranteed convergence. By tuning the optimization parameters such as degree Q of the polynomial phase behavior, sub-sequence length M and the total number of sub-sequences L, the optimized sequences can be as Doppler tolerant as FMCW waveform in one end, and they can possess small cross-correlation values similar to random-phase sequences in PMCW waveform on the other end. If required in the event of acute interference, new codes can be generated in the runtime which have low cross-correlation with the interferers. The performance analysis indicates that the proposed method outperforms the state-of-the-art counterparts.