2-D DOA ESTIMATION OF LFM SIGNALS FOR UCA BASED ON TIME-FREQUENCY MULTIPLE INVARIANCE ESPRIT

In order to improve the angle measurement precision with a low computational complexity, a 2-D direction of arrival (DOA) estimation algorithm UCA-TF-MI-ESPRIT is proposed in this paper. This algorithm is based on the mode space algorithm and the time-frequency (TF) multiple invariance rotational invariance technique (MI-ESPRIT). Firstly, a uniform circular array (UCA) is equivalent to a virtual uniform linear array (ULA) by utilizing mode-space algorithm. Then, the smoothed pseudo Wigner-Ville distribution (SPWVD) of the ULA output is calculated. The spatial time-frequency matrix can be obtained through the average of multiple time-frequency points in the time-frequency plane, and the signal subspace can also be obtained through using eigen decomposition. Then a simple and effective subarray dividing approach is proposed, and the multiple rotational invariant equation of the array is obtained by using the Bessel function. Finally, the closed-form solution is obtained using multi-leastsquares (MLS) criterion so that the 2-D DOA estimation of LFM signals in UCA is completed. The simulation results verify the effectiveness of the algorithm proposed by this paper.