Adaptive multiuser CDMA detector for asynchronous AWGN channels-steady state and transient analysis

A two-stage adaptive multiuser detector in an additive white Gaussian noise code-division multiple-access channel is proposed and analyzed. Its first stage is an asynchronous one-shot decorrelator which in terms of computational complexity only requires inversion of K symmetric K/spl times/K matrice...

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Bibliographic Details
Published inIEEE transactions on communications Vol. 48; no. 9; pp. 1541 - 1549
Main Authors Zhong, L.C., Siveski, Z., Kamel, R.E., Ansari, N.
Format Journal Article
LanguageEnglish
Published New York IEEE 01.09.2000
The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subjects
Additive white noise
Algorithms
Amplitude estimation
AWGN
Channels
Computation
Computational complexity
Concurrent computing
Decisions
Decorrelation
Detectors
Estimates
Interference
Inversions
Multiaccess communication
Multiple access interference
Symmetric matrices
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Summary:A two-stage adaptive multiuser detector in an additive white Gaussian noise code-division multiple-access channel is proposed and analyzed. Its first stage is an asynchronous one-shot decorrelator which in terms of computational complexity only requires inversion of K symmetric K/spl times/K matrices for all K users. In addition, the K inversions can be done in parallel, and the computed results for one user can be reused by all other users as well, resulting in a latency of only one bit, same as its synchronous counterpart. The decorrelated tentative decisions are utilized to estimate and subtract multiple-access interference in the second stage. Another novel feature of the detector is the adaptive manner in which the multiple-access interference estimates are formed, which renders prior estimation of the received signal amplitudes and the use of training sequences unnecessary. Adaptation algorithms considered include steepest descent (as well as its stochastic version), and a recursive least squares-type algorithm that offers a faster transient response and better error performance. Sufficient conditions for the receiver to achieve convergence are derived. The detector is near-far resistant, and is shown to provide substantial steady-state error performance improvement over the conventional and decorrelating detector, particularly in the presence of strong interfering signals.
Bibliography:ObjectType-Article-2
SourceType-Scholarly Journals-1
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ISSN:0090-6778
1558-0857
DOI:10.1109/26.870021