Title :
Turbo Multiuser Detection for MC-CDMA Downlink Systems with Transmit Diversity
Author :
Jiménez-Pacheco, Alberto
Author_Institution :
Dept. of Signals, Syst. & Radiocommun., Univ. Politecnica de Madrid
Abstract :
Multi-carrier code division multiple access (MC-CDMA) and space-time block coding (STBC) are two promising techniques to fulfill the high-speed and spectral efficiency requirements of fourth generation wireless communication systems. In this contribution we present a turbo iterative receiver for the downlink of STBC MC-CDMA systems, that aims to mitigate the effects of multiple access interference (MAI) by jointly optimizing multiuser detection and channel decoding. Our proposal is a parallel interference canceller (PIC), where soft information in the form of log-likelihood ratios (LLRs) is exchanged between the multiuser detector (MUD) and individual convolutional decoders for successive refinement. To reduce complexity, a simple linear space-time combiner eliminates co-antenna interference (CAI) before delivering its output to the cancellation loop. Thus, the MUD is adapted to the equivalent channel as seen after space-time combining, and is designed according to the MMSE criterion, modified to take into account a priori information derived from previous iterations. Several suboptimum variants of this scheme are also discussed and compared in terms of complexity and performance.
Keywords :
4G mobile communication; block codes; channel coding; code division multiple access; convolutional codes; decoding; diversity reception; interference suppression; least mean squares methods; multiuser detection; radio receivers; space-time codes; MC-CDMA downlink systems; MMSE criterion; channel decoding; co-antenna interference; convolutional decoders; fourth generation wireless communication systems; linear space-time combiner; log-likelihood ratios; multi-carrier code division multiple access; multiple access interference; parallel interference canceller; space-time block coding; spectral efficiency requirements; transmit diversity; turbo iterative receiver; turbo multiuser detection; Block codes; Diversity reception; Downlink; Interference cancellation; Iterative decoding; Multicarrier code division multiple access; Multiple access interference; Multiuser detection; Proposals; Wireless communication;
Conference_Titel :
Vehicular Technology Conference, 2007. VTC2007-Spring. IEEE 65th
Conference_Location :
Dublin
Print_ISBN :
1-4244-0266-2
DOI :
10.1109/VETECS.2007.548