What is the interference mitigation strategy for automotive radar when many vehicles have radar?

The interference mitigation strategy for automotive radar addresses the growing problem of mutual interference when many vehicles in close proximity operate 77 GHz FMCW radars simultaneously. Interference occurs when another vehicle's radar signal is received by the victim radar, creating: ghost targets (false detections at ranges and velocities determined by the relative chirp parameters of the interfering and victim radars), elevated noise floor (wideband interference that reduces the victim radar's SNR and detection range), and target masking (interference energy overwhelming the true target echoes in specific range-Doppler cells). The mitigation strategies include: randomized chirp parameters (each radar randomizes its chirp start time, chirp slope, and center frequency within the 76-81 GHz band, reducing the probability that two radars have correlated chirp parameters; the resulting interference appears noise-like and spreads across many range-Doppler cells rather than creating strong ghost targets), interference detection and excision (the radar's DSP detects interference in the time-domain ADC data by identifying samples with abnormally high amplitude, and replaces the corrupted samples with interpolated or zero values before performing the FFT; this removes 90-99% of interference energy with minimal impact on target detection), waveform diversity (using frequency-division or code-division multiplexing so that each radar occupies a different portion of the spectrum or uses a different code; PMCW (phase-modulated continuous wave) radar inherently provides better interference rejection than FMCW because the coded waveform has processing gain against uncorrelated interference), and cooperative interference management (future vehicle-to-vehicle communication could coordinate radar parameters among nearby vehicles to avoid spectral conflicts; this is an active research area).