Efficient Target Discrimination in MPSK-MIMO FMCW Radar

Abstract

In multi-input multi-output (MIMO) frequency-modulated continuous-wave (FMCW) radar, various multiplexing schemes are considered to transmit the signals orthogonally. In particular, in code-division multiplexing (CDM), waveform at each Tx antenna is modulated by different phase code to achieve orthogonality so that waveforms can be transmitted simultaneously. However, the M phase-shift keying (MPSK) code for M Tx antennas reduces the maximum unambiguous velocity, causing a Doppler ambiguity problem. Therefore, we propose an efficient method to resolve this ambiguity. The proposed method first estimates the direction-of-arrival (DoA) of the target and constructs a candidate sequence for the phasors of the detected peaks. Then, it compares the constructed candidate sequence with the reference sequence to find the true peaks. Simulations and experiment results obtained using a commercial MIMO FMCW radar demonstrate the effectiveness of the proposed method. Finally, the advantage of the proposed method is shown through a comparison with conventional methods for overlapped targets.