Blind beamforming for rectilinear signals

Automatic beamforming for noncircular signals with distinct noncircularity-rates can be achieved via Takagi factorization based on the second-order statistics. However, the requirement on noncircularity-rate diversity can not be satisfied by rectilinear signals (e.g., AM and BPSK signals), which are used in many practical communications systems. A mixed-order Takagi factorization scheme is herein proposed to handle coexisted rectilinear signals, wherein the fourth-order statistics is used for adjusting virtually the noncircularity-rates of signals, while the second-order statistics is utilized for blind identification. Numerical examples are also included to illustrate the performance of the proposed beamformer.