The generalized constant modulus algorithm applied to multiuser space-time equalization

The generalized constant modulus criterion and algorithm (GCMA) was proposed by Cavalcanti, Brandao and Romano (see Proc. Globecom/Comm. Theory Mini-Conference, Sydney, Australia, 1998) as a blind equalization technique for combating intersymbol interference in single-user systems. In this paper we extend this concept for the blind separation and equalization of multiple users in presence of intersymbol interference. The proposed criterion and algorithm can be viewed as a generalization of CMA in the sense that any constant modulus signal produced at the processor's output satisfies the criterion. An LMS-type algorithm is derived and compared with the CMA in the context of multiuser space-time equalization. An enhanced method for the decorrelation of multiuser signals is also presented as part of the proposed space-time equalizer.