Performance analysis of adaptive widely linear beamformers

In this paper, we consider the problem of enhancing the filtering capacity of single standard beamformers for real base-band signals. Unfortunately, the standard smart arrays are not able to effectively minimize the effects of the complex noise in the array. In order to solve this problem, we analyze a parallel adaptive beamforming system based on complex nonlinear adaptive filters. In this design, the smart array is used as a widely linear (WL) system in which the second order statistical information of the signals is exploited by using the covariance and pseudo-covariance matrices. The simulations results show this architecture has a lead filtering capability as well as an outstanding generation of the radiation patterns. Furthermore, this parallel hybrid array showed to have a better filtering capacity than the standard arrays LMS, NLMS and RLS. General equations for the optimal weight vector are derived for this augmented complex (AC) smart array or widely linear beamforming.