Orthonormal Subspace Tracking Algorithm for Space–Time Multiuser Detection in Multipath CDMA Channels

This paper presents the techniques of space-time blind multiuser detection based on signal subspace estimation for asynchronous multipath antenna array code-division multiple access systems. The proposed techniques only require the prior knowledge of spreading waveform and timing information of the desired user. The normalized orthogonal Oja (NOOja) subspace tracking algorithm is used for adaptive subspace estimation, and the Kalman-type algorithm is employed for adaptive channel estimation of the asynchronous multipath antenna array system. Simulation results show that the NOOja subspace tracking algorithm is adaptively used to achieve a better performance than other similar orthogonal subspace tracking algorithms.