MULTIDIMENSIONAL MULTIRATE DOA ESTIMATION IN BEAMSPACE

This paper presents a beamspace version of ESPRIT for uniform rectangu lar arrays that supports closed-form 2-D angle estimation, automatical ly couples the two components of the source directions, and works with any front end beamformer. The proposed algorithm is based on the obse rvation that beamspace noise eigenvectors can be transformed to vector s that are bandpass and have spectral nulls at the inband source locat ions. This facilitates multirate processing (involving modulation to b aseband, filtering, and decimation) and yields a space with dimensiona lity equal to the number of beams used to probe the subband rather tha n the number of elements in the sensor array. The MUSIC algorithm can be applied to this noise subspace. Alternatively, a transformation mat rix can be computed a pylori, which maps the beamspace signal eigenvec tors to the corresponding signal subspace that has the ESPRIT structur e. The TLS-ESPRIT algorithm is then modified to obtain the two directi ons for each source from a single eigenvalue-eigenvector pair. Hence, they are automatically coupled.