TY  - JOUR
T1  - Efficient WL Beamforming with Projection onto Interference Null Space
AU  - Choi, Yang-Ho 
JO  - The Journal of Korean Institute of Communications and Information Sciences
PY  - 2025
DA  - 2025/1/1
DO  - 10.7840/kics.2025.50.5.764
KW  - Interference null projection
KW  - Noncircular signals
KW  - Widely linear
KW  - Conjugate symmetry
AB  - In case noncircular signals are incident into a sensor array the performance of a beamformer can be improved by introducing the widely linear (WL) scheme. When the incident signals are strictly noncircular, in which the magnitudes of the noncircular coefficients are one, an efficient WL beamforming method is proposed through the interference null space projection. In the proposed method, the arrival angle and the initial phase of the desired signal are estimated via the search over its direction sector by NC-MUSIC (noncircular multiple signal classification) to attain an extended steering vector. Utilizing it, the interference subspace is effectively estimated by removing the desired signal component from the eigendecomposition of the sample matrix. The weight vector is computed such that it is orthogonal to the estimated subspace. The computational burden is light since most computations are carried out with real numbers by using the conjugate symmetry of the extended received vector. Simulation results show that it has robustness against pointing errors, outperforming existing WL beamformers including the one dealing with a very complex nonlinear problem to overcome steering vector errors.