Multiple signal cancellation for narrowband beamformers

In this paper, we use Cholesky signal decomposition procedure to effortlessly analyze the narrowband beamformers for cases of multiple correlated signals. If the desired signal and a fully correlated interference both exist, it is well known that the beamformer will produce the so-called signal cancellation. As for multiple correlated signals, the analysis of the beamformer becomes burdensome in development of the constrained multiple parameters optimization. With the proposed analyses, the general signal cancellation conditions, characterized by correlations, powers, and directions of arrival of signals, are easily explored to uncover the weakness of the beamformer for modern wireless communications. The detailed discussions and simulations in various scenarios are then presented to verify the theoretical derivations.