Nonlinear Stepped-Frequency MIMO PMCW Radar Systems with High Range Resolution Under Low Sampling Rates

Phase-modulated continuous-wave (PMCW) radar systems are gaining interest for autonomous sensing. However, high range resolution typically demands prohibitively high sampling rates and computational loads. To address this issue, we propose a novel nonlinear stepped-frequency PMCW (NSF-PMCW) radar system. The proposed NSF-PMCW radar system periodically transmits sequences whose carrier frequency varies nonlinearly over time, and the associated signal processing method synthesizes a wide effective bandwidth by processing and coherently summing these frequency-varying sequences. This approach successfully enhances the range resolution without increasing the bandwidth and sampling rate of the analog-to-digital converter. Furthermore, we propose an angle estimation algorithm that accounts for the time-varying frequency of sequences to improve the estimation accuracy. The simulation results show that the proposed system can achieve the range resolution of a 3 GHz PMCW radar system while using only 500 MHz of bandwidth with a root mean square error of 0.0081 m in range estimation and 0.1114∘ in angle estimation.