Direction and spread estimation of spatially distributed signals via the Power Azimuth Spectrum

In wireless communications involving antenna arrays, it is desired to estimate the nominal direction and spatial spread of spatially distributed signals, which originate from local scattering around the transmitter. Spatially distributed signals cause conventional high-resolution methods to show degradation in performance, since the underlying data model theoretically is of full rank. Therefore, DOA estimation of spatially distributed signals has recently gained interest in the array processing society, ´and new high-resolution estimators for distributed signals have been proposed. This paper investigates the use of classical beamforming methods, such as conventional beamforming and Capon´s beamformer, to estimate both the nominal DOA and spatial spread of a distributed signal. Finally, numerical examples comparing the performance of two high-resolution methods with the proposed methods, are presented.