A Unified Model and Survey on Modulation Schemes for Next-Generation Automotive Radar Systems

Commercial automotive radar systems for ADAS have relied on FMCW waveforms for years due to their low-cost hardware, simple signal processing, and established academic and industrial expertise. However, FMCW systems face challenges, including limited unambiguous velocity, restricted multiplexing of transmit signals, and susceptibility to interference. This work introduces a unified automotive radar signal model and reviews alternative modulation schemes such as PC-FMCW, PMCW, OFDM, OCDM, and OTFS. These schemes are assessed against key technological and economic criteria and compared with FMCW, highlighting their respective strengths and limitations.