DocumentCode :
1332552
Title :
Adaptive techniques for multiuser CDMA receivers
Author :
Honig, Michael ; Tsatsanis, Michail K.
Author_Institution :
Dept. of Electr. & Comput. Eng., Northwestern Univ., Evanston, IL, USA
Volume :
17
Issue :
3
fYear :
2000
fDate :
5/1/2000 12:00:00 AM
Firstpage :
49
Lastpage :
61
Abstract :
A number of CDMA receivers have been proposed that cover the whole spectrum of performance/complexity from the simple matched filter to the optimal Viterbi (1995) processor. Adaptive solutions, in particular, have the potential of providing the anticipated multiuser detection (MD) performance gains with a complexity that would be manageable for third generation systems. Our goal, in this article, is to provide an overview of previous work in MD with an emphasis on adaptive methods. We start with (suboptimal) linear receivers and discuss the data-aided MMSE receiver. Blind (nondata-aided) implementations are also reviewed together with techniques that can mitigate possible multipath effects and channel dispersion. In anticipation of those developments, appropriate discrete-time (chip rate) CDMA models are reviewed, which incorporate asynchronism and channel dispersion. For systems with large spreading factors, the convergence and tracking properties of conventional adaptive filters may be inadequate due to the large number of coefficients which must be estimated. In this context, reduced rank adaptive filtering is discussed. In this approach, the number of parameters is reduced by restricting the receiver tap vector to belong to a carefully chosen subspace. In this way the number of coefficients to be estimated is significantly reduced with minimal performance loss.
Keywords :
adaptive filters; adaptive signal detection; adaptive signal processing; cellular radio; code division multiple access; dispersive channels; filtering theory; least mean squares methods; multipath channels; multiuser channels; radio receivers; spread spectrum communication; adaptive filters; adaptive methods; blind nondata-aided implementation; cellular radio; channel dispersion; chip rate; coefficients; convergence properties; data-aided MMSE receiver; discrete-time CDMA models; large spreading factors; matched filter; multipath effects; multiuser CDMA receivers; multiuser detection; optimal Viterbi processor; receiver tap vector; reduced rank adaptive filtering; suboptimal linear receivers; third generation systems; tracking properties; Decoding; Dispersion; Error correction; Filters; History; Multiaccess communication; Proposals; Signal processing;
fLanguage :
English
Journal_Title :
Signal Processing Magazine, IEEE
Publisher :
ieee
ISSN :
1053-5888
Type :
jour
DOI :
10.1109/79.841725
Filename :
841725
Link To Document :
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