2D unitary ESPRIT for efficient 2D parameter estimation

Consider multiple narrowband signals that are incident upon a planar sensor array. 2D Unitary ESPRIT is a new closed-form high resolution algorithm to provide automatically paired source azimuth and elevation angle estimates, along with an efficient way to reconstruct the impinging signals. In the final stage of the algorithm, the real and imaginary parts of the ith eigenvalue of a matrix are one-to-one related to the respective direction cosines of the ith source relative to the two array axes. 2D Unitary ESPRIT offers several advantages over other recently proposed ESPRIT based closed-form 2D angle estimation techniques. First, except for the final eigenvalue decomposition of dimension equal to the number of sources, it is efficiently formulated in terms of real-valued computation throughout. Second, it is amenable to an efficient DFT beamspace implementation. Third, it is also applicable to array configurations that do not exhibit three identical subarrays, as long as the array is centro-symmetric and possesses invariances in two distinct directions, cf. Fig. 2. Finally, 2D Unitary ESPRIT easily handles sources having one member of the spatial frequency coordinate pair in common.