Partial Nulling Beamforming for MIMO Signal De-correlation

The patent applies partial nulling by controlling the nulling factor alpha (0 ≤ alpha < 1) to nullify only a portion of the interference signals rather than completely eliminating them. This partial action achieves sufficient signal de-correlation while preserving more of the desired signal energy, thus maintaining receiving gain. The beamforming weight vector is calculated as w = (αR_s + (1-α)R_i)^-1 h, where by adjusting alpha, the system balances between interference suppression and signal preservation.

The patent transforms the traditional eigenvalue decomposition approach into a direct matrix inversion method by parameterizing the solution through the nulling factor alpha. Instead of performing full eigenvalue decomposition to find eigenvectors, the system directly computes the beamforming weight vector using w = (αR_s + (1-α)R_i)^-1 h, where R_s and R_i are signal and interference covariance matrices. This parameterized approach reduces computational complexity while maintaining beamforming accuracy through the controllable alpha parameter.

The patent segments the total receiving signals into two distinct components: desired signal components (R_s) and interference signal components (R_i). By separating these components and applying different weighting through the alpha parameter, the system can selectively emphasize signal preservation (when alpha is close to 1) or interference suppression (when alpha is close to 0). This segmentation allows the beamformer to independently control how much of each component is nulled, achieving both information preservation and interference de-correlation.