A parallel fractional adaptive single-user receiver for asynchronous CDMA systems

An alternative structure for a single user-detector is considered, using the minimum mean square error (MMSE) criterion. The proposed structure uses both the advantages of the equal spaced equalizer (ESE), in terms of the convergence rate, and of the fractional spaced equalizer (FSE), in terms of its inherent immunity to variations of sampling phase. The adaptive receiver has no knowledge of the signature waveforms of all the active users, even that of the desired user. The receiver is trained by a known training sequence prior to data transmission and continuously adjusted by an adaptive algorithm during data transmission (decision directed mode). The receiver structure is investigated and tested by simulation using a processing gain of 31. Considerable improvement is achieved with respect to the conventional receiver