Impact of laser phase noise on the ranging accuracy of a cooperative MIMO FMCW photonic radar system

In this paper, a FMCW-based cooperative 2×2 MIMO photonic radar system using heterodyne detection is presented. The proposed system consists of two separate sensor nodes that use a linear frequency modulated continuous wave signal, which allows simultaneous monostatic and bistatic radar measurement, where the target range and angle of arrival information are extracted. The additional bistatic information enhances the target detection and estimation capabilities with improved accuracy. This accuracy in practicality is affected by the laser phase noise, which degrades the overall system performance. Here, the analytical laser phase noise model for the MIMO system is derived and implemented to analyze its impact on the ranging accuracy of the proposed system. Under the impact of standard white Gaussian laser phase noise assumption, the monostatic and bistatic response of the detected signal is measured and compared using statistics of measurement error. Further, the signal-to-noise ratio and SSB laser phase noise of the monostatic and bistatic response are measured and compared at different target ranges. At last, the phase-noise-limited ranging accuracy of the system is evaluated and analyzed. The concept shown in this work paves the way for advanced photonic radar system applications such as modern radar systems, electronic warfare systems, metrology, and automotive vehicle radar with multiperspective coherent detection.