Blind adaptive multiuser detection in DS-CDMA systems

Abstract

The study of multiuser detection techniques for the multi-access interference (MAI) suppression in DS-CDMA systems captures the attentions of many researchers for recent few years. Even though various multiuser detectors have been developed, most of them are of linear structure, which limits their performances due to the nonlinearity of the signals involved. Therefore, in this research, two nonlinear blind adaptive interference cancellation algorithms (the exact Newton (EXN) and the approximate Newton (APN)) were proposed and developed based on the 2nd order Volterra expansion. Attractively, both the numerical results and the theoretical analysis results show that the proposed nonlinear EXN and APN algorithms can detect the desired signals successfully in the presence of strong MAI. In particular, the APN algorithm can obtain almost identical BER performance as the EXN algorithm at a higher numerical stability and lower computational complexity.