Improved orthogonal projection adaptive beamforming based on normalization at subarray level

Orthogonal projection (OP) adaptive beamforming is widely applied in practical scenarios because of strong robustness. However, the performance of traditional OP adaptive beamforming would degrade severely when OP adaptive beamforming is applied at subarray level, especially in asymmetrical subarray configuration. To overcome this problem, the improved orthogonal projection (IOP) adaptive beamforming based on normalization at subarray level is proposed. In the proposed method, the covariance matrix is firstly modified by normalizing the noise power at subarray level. Subsequently, the interference subspace is estimated by eigenvalue decomposition, and then the adaptive weight is calculated by using OP adaptive beamforming. Numeral simulation results show that the proposed method at subarray level outperforms the traditional OP adaptive beamforming and the output signal-to-interference-plus-noise ratio (SINR) is close to the optimum value. The proposed method can be significantly effective in practical applications.