A robust adaptive array beamformer using particle swarm optimization for space-time code division multiple access systems

An adaptive beamformer often suffers from severe performance degradation when a mismatch exists in the steering vector of interest. In this study, a new approach to the robust adaptive beamforming technique is proposed based on minimum variance distortionless response (MVDR) for space-time systems. The proposed method combines particle swarm optimization (PSO) and Taylor series expansion to enable the use of direction-of-arrival (DOA) estimation. Taylor series expansion can be robust to pointer errors for the presumed steering vector. However, the Taylor approach is easily trapped at a local minimum, causing errors in DOA estimation. Therefore, a more accurate DOA estimate is necessary for MVDR beamforming. To resolve this problem, a DOA estimation approach featuring a high resolution and low computational load is presented in this paper. An initial DOA estimate is first determined using a PSO estimator. Next, the predominant DOA estimate is sent to the Taylor series expansion-based estimator to form an estimate. Several simulation results are provided to demonstrate the effectiveness of the proposed approach. (C) 2014 Elsevier Inc. All rights reserved.