Direct computation of a minimum-variance distortionless-response beamformer

A QR-decomposition constrained least-squares (QRD-CLS) algorithm is presented to solve directly for a minimum-variance distortionless-response adaptive beamformer without explicit computation of its weights. Generally, the QRD-CLS algorithm is capable of solving deterministic least-squares optimization problems subject to an equality constraint in an iterative adaptive manner by imposing a `soft´ constraint via the quadratic penalty function optimization method. The proposed algorithm is able to perform both linearly constrained and unconstrained least-squares minimizations; in addition, it is implemented with a unique triangular systolic array architecture where an orthogonal triangularization process is performed on the input data by means of new `three-dimensional´ Givens rotations