Multi-User Detection and Chip Sequence Estimation of multi-path CDMA signal Based on Blind Beamforming

Based on the relationship of the subspace of the received signals and the spreading code of users, a novel subspace algorithm that can blindly estimate spreading code sequences of multi-path code division multiple access (CDMA) signals was presented, in non cooperative communication surroundings. Without the information of the direction of arrival (DOA) of all source signals, this novel subspace algorithm was proposed to get the coefficients of the beam former based on complex independent component analysis (CICA) . A new algorithm which is fit for multi-user detection of multi-path signals was also proposed, without the information of the spreading code sequences and the direction of arrival of source signals. The performance of the proposed algorithm was analyzed, and the close expression of the performance under Gaussian noise was given. Because of utilizing the spreading gain and the array antenna gain, this proposed beam forming algorithm performs better than the traditional algorithm of single antenna. The effectiveness of the proposed algorithm was showed by the illustrative simulation results at last.