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Proceedings Paper

Multiuser differential-PSK demodulators for DS/CDMA signals
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Paper 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.

Paper Details

Date Published: 26 July 2000
PDF: 12 pages
Proc. SPIE 4045, Digital Wireless Communication II, (26 July 2000); doi: 10.1117/12.394090
Show Author Affiliations
George N. Karystinos, SUNY/Buffalo (United States)
Dimitris A. Pados, SUNY/Buffalo (United States)

Published in SPIE Proceedings Vol. 4045:
Digital Wireless Communication II
Raghuveer M. Rao; Soheil A. Dianat; Michael D. Zoltowski, Editor(s)

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