This study proposes an advanced direction-of-arrival (DOA) estimation method for automotive multiple-input multiple-output (MIMO) fast-ramp radar systems. To distinguish the transmitted signal at the receiving antenna, the orthogonal code can be applied to each transmitted signal. In this case, to correctly estimate the angles of the targets, the authors also have to match the distinguished signals to each transmit antenna element. In this study, they use the space-time block code to distinguish the transmitted signals from the receiving antennas. Furthermore, by applying the deterministic maximum likelihood algorithm to each of the distinguished signals, they can find the true antenna array for DOA estimation and achieve higher estimation accuracy than false antenna array cases. Furthermore, the maximum detectable velocity is doubled compared to the conventional decoding method. In the simulation results, the proposed method provides a three degree smaller root-mean-squared error compared to the case when it is not applied. The proposed method also estimates the DOAs of the targets well at low signal-to-noise ratios. In addition, the effectiveness of the proposed method was verified by measurement results.

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Improved DOA estimation method by distinction of different transmit signals in automotive MIMO frequency-modulated continuous wave radar systems

References

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