Multi-Frequency Sparse Array-Based Massive MIMO Radar for Autonomous Driving

In this paper, we propose the concept of high-resolution massive multiple-input multiple-output (MIMO) radar with large-aperture sparse arrays for autonomous driving by exploiting multi-frequency signaling. The diversity offered by multi-frequency signals renders a high number of virtual sensors that effectively increase the degrees of freedom. Two strategies are developed to synthesize virtual sparse arrays by jointly utilizing MIMO radar sum coarray and multi-frequency signaling, respectively with and without further incorporating the difference coarray concept. As an example, we synthesize sparse arrays with an aperture of around 100 normalized half-wavelength using only 7 physical array elements in the context of the proposed multi-frequency MIMO radar.