Orthogonal projection method for array signal subspace estimation

To lower the high computational burden caused by the eigenvalue decomposition (EVD) based subspace estimation methods, a new orthogonal projection (OP) based fast subspace estimation method is proposed. Basis of the subspace is calculated iteratively by OP without EVD. The signal energy in each basis direction is maximized to guarantee the maximum signal energy in the spanned signal-subspace. The signal-subspace estimation error function and the noise-subspace estimation error function are defined to evaluate subspace estimation performance. Theoretical analysis and simulation results show that the OP algorithm is computationally simple and with even-better subspace estimation performance compared with EVD.