Distributed Microwave Photonic MIMO Radar With Accurate Target Position Estimation

A distributed microwave photonic multiple-input multiple-output (MIMO) radar is presented to accurately estimate the two-dimensional (2-D) position of targets. With wavelength-division-multiplexing-based recirculating frequency shifting, mutually orthogonal broadband stepped-frequency chirp (SFC) signals can be produced simultaneously, avoiding the complex implementation of a distributed MIMO radar. Microwave photonic dechirping is also performed to process broadband echoes, while a bandwidth synthesis is carried out to fast and accurately estimate the time of arrival (TOA). Thus, 2-D localization can be obtained by a back-projection (BP) algorithm. In a proof-of-concept experiment, a
$2\times2$
MIMO radar with a bandwidth of 18 GHz is conducted, providing a 1-D ranging error of
$< \pm 1$
mm and a 2-D positioning error of < 1 cm.