DoA estimation based on 2D-ESPRIT algorithm with multiple subarrays in hexagonal array

A scheme of direction-of-arrival (DoA) estimation is proposed based on 2D-ESPRIT algorithm with multiple combinations of subarrays. The pairs of elevation and azimuth angles are obtained by applying the standard 2D-ESPRIT algorithm to three combinations of two set-of-subarrays in a 7-element hexagonal array. The pairs obtained from one of three combinations are permuted according to the descending order of azimuth. For the l-th DoA, its candidate pairs of estimation are formed from the elevations and azimuths in the three l-th pairs. The l-th DoA is selected among the candidate pairs, based on the selection criterion with 2D-MUSIC spectrum. Benefiting from the three combinations, the proposed scheme suppresses the estimate error arisen from the relation of a practical value of DoA and the translational invariance subarray. Simulation shows that the proposed scheme reduces the root mean square error, compared with the standard 2D-ESPRIT algorithm with a single combination.