Conjugate music for non-circular sources

This paper proposes a method for the direction of arrival (DOA) estimation for non-circular sources, such as binary phase shift keying (BPSK) and M-ary amplitude shift keying (MASK). The proposed scheme can be applied to both scenarios; the sources are noncoherent or coherent. Comparisons that are made with the well-known classical subspace algorithms, such as MUSIC and forward/backward smoothing by Pillai et al., show that the proposed method has several advantages. First, no forward/backward spatial smoothing for the covariance matrix is needed, whereas the Pillai method requires it, which increases the computational load and is time-consuming. Second, the proposed method can detect N-1 coherent sources when N antennas are used, whereas the well-known Pillai method can only detect 2N/3 coherent sources. Third, the proposed method is more suitable for real-time implementation since it only requires a single or few snapshots in order to give an accurate DOA estimation. However, both MUSIC and Pillai require a high number of snapshots, which increases the computational cost and memory storage. Simulation results show that the proposed method has better performance, compared to the forward/backward spatial smoothing by the Pillai and MUSIC Algorithm.