Music-based DOA estimation by oblique projection along the signal subspace

In the MUSIC-based direction of arrival (DOA) estimation technique, the orthogonal projection of a steering vector onto the so-called noise subspace plays a crucial role. The noise subspace is defined as the orthogonal complement of the signal subspace spanned by the unknown true steering vectors of target signals, which implies that the correlation structure of noise does not contribute to the DOA estimation performance after the signal subspace is specified. In this paper, we introduce a novel noise subspace, called the proper noise subspace, which is a complementary subspace of the signal subspace and reflects the correlation structure of the noise; and construct a novel MUSIC-based DOA estimation algorithm based on the oblique projector onto the proper noise subspace along the signal subspace.