Coherent Multistatic MIMO Radar Networks Based on Repeater Tags

Abstract

In this paper, a coherent multistatic radar network with a novel system architecture is presented, which circumvents the general problems of clock distribution and phase noise-related signal-to-noise ratio (SNR) issues. The proposed network consists of a variable number of multiple-input multiple-output (MIMO) radar sensors and a variable number of repeater tags, all of which operate incoherently on the hardware level. In a minimum configuration, the network only consists of one MIMO radar sensor and a repeater tag. The theory behind such a multistatic network is mathematically derived, and simulations are presented to show key aspects of the network, i.e., multistatic range and Doppler measurements, as well as high-resolution angle estimation, exploiting a very large virtual aperture spanning the whole network. Measurements with one sensor and one repeater tag at 77 GHz are carried out to verify the simulations. The measurements show that the bistatic path between the sensor and the repeater tag retains coherency.

Automotive Radar — From First Efforts to Future Systems

“…A concepts for N FMCW-sensors was presented in [96] with coherent processing in [97]. Alternative concepts comprise the integration of radar repeaters into the networks [98]. Even interferometric concepts have recently been proposed [99].…”

“…Most of those network approaches suffer from very sparse apertures and therewith angular ambiguities, in particular if the apertures span large parts of the vehicle. A typical countermeasure to suppress ambiguities in the angular domain is CS [98], as presented before.…”

OFDM-Based Radar Network Providing Phase Coherent DOA Estimation

“…In [13], a concept for a cooperative sensor network based on frequency-modulated continuous wave (FMCW) MIMO radars and repeater elements is presented. The repeater receives and retransmits the radar signal reflected at the targets and therefore provides an additional signal, which in the following is called a bistatic signal.…”

“…Due to the low modulation frequency, the additional phase noise introduced is much smaller than the phase noise from the radar sensor and therefore negligible. When using an FMCW radar, the modulation shifts the bistatic targets in range and velocity and separates them from the monostatic ones [13]. However, every range-Doppler (Rv)-peak has to be assigned individually to the radar and the different repeater elements, This work is licensed under a Creative Commons Attribution 4.0 License.…”

“…In this work, a reconstruction of the unknown modulation phase of each repeater is performed. In contrast to the signal processing proposed in [13], this provides the possibility to evaluate the path differences between the repeaters. In this way, a coherent phase progression similar to the steering vector of a MIMO radar can be generated by combining the phases of the bistatic signals.…”