A low-complexity DOA estimation algorithm based on Nyström method for mixed signals

In this paper, a fast decorrelation DOA (direction-of-arrival) estimation algorithm for mixed signals (coherent signals and uncorrelated signals coexist) is proposed. First, the approximate signal subspace of the array output is obtained by Nystrom method, which can reduce the computational complexity. Then, the eigenvectors of the signal subspace are used to reconstruct the matrix for direct decorrelation preprocessing. Finally, the unitary transformation is used to transform the reconstructed matrix into a real-valued matrix for faster DOA estimation. The proposed algorithm does not need to directly calculate the covariance matrix of the array output and does not need to perform decorrelation preprocessing on the covariance matrix, which reduces the computational complexity and can perform DOA estimation when coherent and uncorrelated signals exist simultaneously. The simulation results show that this algorithm can effectively estimate DOA while reducing the computational complexity.