Blind Multi-User Equalisation for a Dispersive DS-CDMA Downlink under Carrier Frequency Offset Conditions

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Description/Abstract

We address blind multiuser detection in a DS-CDMA downlink channel in the presence of carrier frequency offset. The synchronous users are separated by re-establishing orthogonality of their spreading sequences in a shared equaliser at the chip level. The adaptation algorithm is based on a constant modulus criterion of the various users, for which a stochastic gradient descent algorithm can be derived. We show that the resulting filtered-error filtered-regressor algorithm requires modifications in order to cope with carrier offset, and propose an combined blind multiuser equaliser with blind carrier frequency offset estimation. Simulations demonstrating the algorithm's convergence and BER performance are presented.