Over-the-Air Synchronization for Coherent Digital Automotive Radar Networks

Radar networks can offer superior performance compared to individual sensors. However, synchronization is crucial for realizing such a radar network coherently. Digital systems, in particular, provide new opportunities for over-the-air synchronization via signal processing. To synchronize the nodes of a digital radar network, correction of the carrier frequency offset (CFO), sampling frequency offset (SFO), and timing offset (TO) is necessary. A coarse synchronization can be achieved, for example, afterward through low-frequency (LF) coupling of the individual sensors, with fine synchronization realized through signal processing. For fine synchronization, either a target or coupling between the two radar sensors with sufficient signal-to-noise ratio (SNR) is required. The limits of this synchronization approach are primarily defined by the range and Doppler shift ambiguities of the individual sensors. In this article, simulations and measurements demonstrate the feasibility of such a system.