Coherent MIMO Radar Systems in Three-Dimensional Surveillance Scenarios

In this paper, a coherent multiple-input multiple-output (MIMO) radar system with widely separated antennas is simulated in three-dimensional (3D) surveillance scenarios. This analysis proceeds in parallel with the design and development of a system demonstrator based on photonic technology. Microwave photonics permits to conceive an architecture where all radar signals are coherently generated and received in a photonics-based central unit and optically distributed/collected to/from the radar heads where antennas are located, through optical fiber links, maintaining the coherence. Albeit centralized coherent data fusion becomes possible, preliminary results show how secondary lobes represent the major limiting factor for the radar's performance. Nonetheless, diversity in the spatial and/or frequency domains become a crucial resource to circumvent this problem. A MIMO radar simulator is proposed to estimate the coherent ambiguity function in 3D multi-target multi-band scenarios. Preliminary simulation results, concerning 3D scenarios considered of high interest for automotive and other applications, show that coherence in MIMO systems allows to achieve an angular and height resolution very close to the theoretical limit given by the used RF wavelength and baseline length, thus confirming the huge potential of coherent MIMO radars in 3D applications.