Waveform Design for 4D-Imaging mmWave PMCW MIMO Radars with Spectrum Compatibility

4D-imaging mmWave radars offer high angular resolution in both azimuth and elevation, but achieving this requires a large antenna aperture size and a significant number of transmit and/or receive channels. This presents a challenge for designing transmit waveforms that must be separable on the receive side and have low auto-correlation sidelobes. This paper focuses on designing an orthogonal set of sequences for 4D-imaging radar sensors based on PMCW technology. We propose a Coordinate Descent-based iterative optimization framework that optimizes a set of phase-modulated constant modulus waveforms based on weighted integrated sidelobe levels on the required region of interest. The optimization also incorporates the radar’s proximity to other radar sensors and communication systems by spectrum shaping. The efficiency of the suggested strategy, which achieves low sidelobe levels and is compatible with spectrum limits, is shown through simulation results.