Institutional Repository
Technical University of Crete
Technical University of Crete
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| URI: | http://purl.tuc.gr/dl/dias/98DF371B-9C02-47B7-A5C7-D70696DBAE59 | ||
| Year | 2000 | ||
| Type of Item | Conference Full Paper | ||
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| Bibliographic Citation | G. N. Karystinos and D. A. Pados, “Multiuser differential-PSK demodulators for DS/CDMA signals,” in Proc. SPIE’s 14th Annual International Symposium, Digital Wireless Communication Conference, 2000, pp. 155-166. https://doi.org/10.1117/12.394090 | ||
| Appears in Collections |
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.
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