A Multi-Carrier-Frequency Random-Transmission Chirp Sequence for TDM MIMO Automotive Radar

摘要

The collocated time-division multiplexing (TDM) multiple-input multiple-output (MIMO) technique and frequency-modulated continuous-wave (FMCW) chirp sequence are widely used in automotive radar because of the low hardware complexity and the high-accurate range and velocity measurements. In conventional TDM chirp sequences, the transmitters are switched according to their natural spatial order (referred to as a fixed sequential order), thereby inducing space-Doppler frequency coupling and a relatively low unambiguous Doppler interval. In this paper, a new FMCW chirp sequence and corresponding signal processing method for TDM MIMO automotive radar are proposed. The novel waveform adopts the concept of random transmission to distort the linear phase relationship between space and Doppler, therefore, overcoming the coupling problem. Then, via compressed sensing processing, the scheme can suppress the sidelobe pedestal arisen in the conventional matched filter for targets detection. Besides, based on multiple-frequency observations of the same targets, the velocity ambiguity can be adequately resolved. Compared with conventional chirp sequence, the proposed scheme simultaneously overcomes the typical TDM MIMO chirp sequence problems, thereby avoiding a reduction in the data rate. Also, the scheme significantly reduces the mutual interference between adjacent systems. The simulations and experimental results demonstrate the effectiveness of the proposed chirp sequence scheme.