Low complexity 2-D DOA estimator for arbitrary arrays: A hybrid MUSIC-based method

The traditional search-based MUltiple Signal Classification (MUSIC) method is often computationally expensive, particulary for the application of joint azimuth and elevation estimation. By means of the manifold separation technique (MST), the search-free root-MUSIC method, which is originally designed for the uniform linear array structures, can be extended to arbitrary arrays and reduce the computation burden to some extent. However, a computationally complex polynomial rooting procedure is still required. In this paper, we propose a computation attractive 2-D direction-of-arrival (DOA) estimator which can be viewed as a hybrid MUSIC-based method. First, we use the MST method to convert the 2D-MUSIC cost function into stand 2D-IDFT form. In doing so, we can obtain the 2-D spatial spectrum by using 2D-FFT. Since a relatively small point number for the FFT is chosen, the DOAs are located roughly. Then the MUSIC method with fine angular grid is utilized to search the DOAs finely within a small angular section. The proposed hybrid method not only alleviates the computation burden of root-MUSIC or MUSIC solely used; it also achieves almost the same DOA estimation performance and is easy to implement.