Multiuser differential-PSK demodulators for DS/CDMA signals

George N. Karystinos; Dimitris A. Pados

doi:10.1117/12.394090

26 July 2000 Multiuser differential-PSK demodulators for DS/CDMA signals

George N. Karystinos, Dimitris A. Pados

Author Affiliations +

Proceedings Volume 4045, Digital Wireless Communication II; (2000) https://doi.org/10.1117/12.394090
Event: AeroSense 2000, 2000, Orlando, FL, United States

Abstract

Second-order multipath channel estimation procedures for direct-sequence code-division-multiple-access communications induce phase ambiguity that necessitates differential phase- shift-keying (DPSK) modulation and detection. The maximum likelihood (ML) single-symbol multiuser DPSK/CDMA detector is derived with direct generalization to multiple-symbol (block) multiuser DPSK/CDMA detection. Exponential complexity requirements limit the use of the ML rule to theoretical lower-bound bit-error-rate benchmarking. Linear filter DPSK demodulators are viewed as a practical alternative. Phase-ambiguous RAKE filtering followed by RAKE-output differential detection is considered. The familiar minimum-variance-distortionless-response (MVDR) PSK/CDMA filter (designed for minimum filter output energy under the constraint of distortionless response in a given RAKE vector direction) adds the valuable feature of active interference suppression; however, minimum disturbance variance at the differential logic output can be claimed formally only in the absence of multipath (no inter-symbol- interference). Short-data-record adaptive alternatives to costly and slow adaptive MVDR implementations are sought in the context of auxiliary-vector filtering. Numerical and simulation studies illustrate the developments.

Citation Download Citation

George N. Karystinos and Dimitris A. Pados "Multiuser differential-PSK demodulators for DS/CDMA signals", Proc. SPIE 4045, Digital Wireless Communication II, (26 July 2000); https://doi.org/10.1117/12.394090

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