EURASIP Journal on Applied Signal Processing 
Volume 2002 (2002), Issue 3, Pages 289-296
doi:10.1155/S1110865702000598

Differential Space-Time Block Code Modulation for DS-CDMA Systems

Jianhua Liu, Jian Li, and Erik G. Larsson

 Department of Electrical and Computer Engineering, P.O. Box 116130, University of Florida, Gainesville 32611, FL, USA
Received 29 May 2001; Revised 27 December 2001

Abstract

A differential space-time block code (DSTBC) modulation scheme is used to improve the performance of DS-CDMA systems in fast time-dispersive fading channels. The resulting scheme is referred to as the differential space-time block code modulation for DS-CDMA (DSTBC-CDMA) systems. The new modulation and demodulation schemes are especially studied for the down-link transmission of DS-CDMA systems. We present three demodulation schemes, referred to as the differential space-time block code Rake (D-Rake) receiver, differential space-time block code deterministic (D-Det) receiver, and differential space-time block code deterministic de-prefix (D-Det-DP) receiver, respectively. The D-Det receiver exploits the known information of the spreading sequences and their delayed paths deterministically besides the Rake type combination; consequently, it can outperform the D-Rake receiver, which employs the Rake type combination only. The D-Det-DP receiver avoids the effect of intersymbol interference and hence can offer better performance than the D-Det receiver.