Wavefield Networked Sensing for High-Resolution Distributed Automotive Microwave Imaging

Coherent multistatic radio imaging is an appealing concept for the forthcoming generation of wireless networks, involving distributed nodes that cooperate to achieve accurate sensing resolution and robustness. This paper presents an application of this concept tailored to the case of vehicular radar networks. The considered scenario assumes a system composed of a number of vehicles equipped with low-performance Radars, operating simultaneously in different frequency channels. On request by one user, all vehicles enter in cooperation mode to receive the echoes produced by the targets in response to all transmitted signals. This mechanism results in the vehicle formation to act as a single distributed multistatic Radar, allowing for a dramatic improvement of spatial resolution. Coherent multistatic processing is enabled by a careful three-step phase synchronization procedure, mandatorily required to synchronize individual oscillators to within a fraction of the carrier cycle and correct navigational data to within a fraction of the carrier wavelength. We demonstrate the significant benefits of cooperative coherent imaging in the considered automotive scenario in terms of both probability of correct detection, evaluated considering several system parameters, as well as resolution capabilities, showcased by experimental results from a dedicated acquisition campaign wherein the cooperation between two vehicles enables the detection of the legs of a pedestrian in close proximity to a parked car.