Adaptive blind source separation and equalization for CDMA
Soheil A. Dianat, Raghuveer Rao · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1999
The problem of separating multiple, independent code division multiple access (CDMA) sources at a single antenna element receiver in the presence of inter symbol interference, co-channel interference and additive white Gaussian noise is addressed. The channels are not known and separation process is required to be blind and adaptive. The system is assumed to consist of multiple users. Only a single user separation is desired. The CDMA channel is assumed to be a multiple-input single-output dispersive channel. The user's codes are assumed to be orthogonal and known to the receiver. The adaptation process is blind and uses the well-known constant modulus (CM) algorithm. The CM approach uses a modulus-corrected version of the output signal in place of the training signal needed in nonblind equalization techniques. The CM algorithm minimizes the deviation of this modulus from a constant in a mean squared error sense. The minimization is done using an LMS-type algorithm.