Blind source separation with space-time analytical constant modulus algorithm in DS-CDMA systems

The constant modulus property of communication signals, such as FM and phase-modulated signals, are often used in blind separation of multiple users. Because there is no training sequence needed, the system transmission efficiency is increased. However the CMA suffers from the complex iteration computation and local minimums. The analytical constant modulus algorithm (ACMA) replaces the problem of finding the weight vector blindly with the equivalent problem of blind source separation in signal subspace. Via joint diagonalization of matrices, each user´s signal can be obtained analytically. Expanding the ACMA of space domain beamforming to space-time domain can improve the performance of blind signal separation of the system. The computation complexity of ST-ACMA is only related to the amount of constant modulus sources. Its performance is similar to ST-CMA algorithm, but it has less computation than ST-CMA and the faster convergence rate. Finally, numerical simulations can illustrate the effectiveness of this algorithm.