Wideband 2-D DoA Estimation With Uniform Circular Array

Direction-of-arrival (DoA) estimation is a critical technique in radio signal-based sensing. With the advancement of integration of sensing and communication, the demand for low-latency sensing based on wideband signals is increasing, thus efficient wideband DoA estimation with high performance is desirable. In this article, an iterative coherent signal-subspace method (CSM) including three main steps in each iteration is proposed for wideband 2-D DoA estimation with a uniform circular array (UCA), the input of which is the narrowband signals at multiple frequency points divided by Fourier transform from the wideband signal. The first step selects partial frequency points for the subsequent focusing process. The second step performs the focusing process with the angle intervals that designed for generating the focusing matrices, where the received signal-subspaces at the selected frequency points are focused into a reference frequency. The DoAs are estimated by the multiple signal classification (MUSIC) algorithm with a range-shrunk spatial spectrum in the third step. The DoA estimation results of the previous iterations are utilized in the subsequent iterations to refine the estimation accuracy. Furthermore, the computational complexity of the proposed method is theoretically analyzed to demonstrate its efficiency. Besides, the Cramér-Rao bound (CRB) of the investigated scenario of DoA estimation is derived as a performance benchmark, based on which the guidelines for estimation performance improvement are provided. The simulation results indicate that the proposed method enjoys preferable estimation performance and efficiency.