Title
Blind Multiuser Detection in Multirate CDMA Based on Cyclic LMS Adaptation
Abstract
The problem of blind adaptive multiuser detection in multirateCDMA systems is considered. Indeed, since symboldetection in multirate CDMA systems requires periodicallytime-varying processing of the observables, classical LMS and RLSadaptive algorithms, which assume that the solution to be trackedis time-invariant or slowly time-varying, are not suited for blindadaptive multiuser detection in a multirate system. While a cyclicRLS algorithm has recently appeared in the literature, thispaper focuses on the development of LMS-based cyclic filteringalgorithms. In particular, cyclic versions of the standard LMSalgorithm, of the LMS algorithm with iterate averaging and of theLMS algorithm with adaptive step-size are derived. Interestingly,the last two algorithms are shown to exhibit a convergence speed close to thatof the cyclicRLS procedure, but with an order of magnitude lower computationalcomplexity.An adaptive procedure for the automatic selection ofthe algorithm periodicity is also presented, which is based on aminimum mean-output-energy criterion, and that obviates theneed for knowledge of the transmitted data-rates from theinterfering signals.Moreover, the case of known multipathfading channels is also examined. In particular, it is shown that theproposed cyclic LMS algorithms can be used to achieve RLS-likeperformance also in the presence of multipath distortion.Extensive computer simulation results, along with some analyticalconvergence results, confirmthat the proposed algorithms are effective and achieve very satisfactoryperformance.
Year
DOI
Venue
2003
10.1023/B:WIRE.0000012273.62935.8a
Wireless Personal Communications
Keywords
Field
DocType
least mean squares,multirate CDMA,DS/CDMA,blind multiuser detection,weak convergence
Convergence (routing),Least mean squares filter,Multipath propagation,Computer science,Control theory,Filter (signal processing),Multiuser detection,Algorithm,Real-time computing,Code division multiple access,Recursive least squares filter,Computational complexity theory
Journal
Volume
Issue
ISSN
27
4
1572-834X
Citations 
PageRank 
References 
1
0.36
22
Authors
4
Name
Order
Citations
PageRank
Stefano Buzzi1195175.30
Vikram Krishnamurthy2925162.74
Marco Lops340750.30
H. V. Poor4254111951.66