An optimal whitening approach to linear multiuser detection

We propose a new linear multiuser receiver for synchronous code-division multiple-access (CDMA) systems, referred to as the orthogonal multiuser (OMU) receiver. Unlike the linear minimum mean-squared error (MMSE) receiver, the OMU receiver depends only on the signature vectors and does not require k...

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Bibliographic Details
Published in:IEEE transactions on information theory Vol. 49; no. 9; pp. 2156 - 2171
Main Authors: Eldar, Y.C., Chan, A.M.
Format: Journal Article
Language:English
Published: New York IEEE 01.09.2003
The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subjects:
Channels
Codes
Correlators
Decorrelation
Demodulation
Electrical engineering
Least squares approximation
Least squares method
Least squares methods
Matched filters
Mathematical analysis
Multiaccess communication
Multiuser detection
Optimization
Receivers
Signal to noise ratio
Signatures
Transformations
Vectors
Vectors (mathematics)
ISSN:0018-9448, 1557-9654
Online Access:Get full text
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Summary:We propose a new linear multiuser receiver for synchronous code-division multiple-access (CDMA) systems, referred to as the orthogonal multiuser (OMU) receiver. Unlike the linear minimum mean-squared error (MMSE) receiver, the OMU receiver depends only on the signature vectors and does not require knowledge of the received amplitudes or the channel signal-to-noise ratio (SNR). Several equivalent representations of the receiver are developed with different implications in terms of implementation. In the first, the receiver consists of a decorrelator demodulator followed by an optimal whitening transformation on a space formed by the signatures. In the second, the receiver consists of a bank of correlators with correlating vectors that are projections of a set of orthogonal vectors, and are closest in a least squares sense to the decorrelator vectors and also closest in a least squares sense to the signature vectors. In the third, the receiver consists of a single-user matched filter (MF) followed by an optimal whitening transformation on a space formed by the signatures. We derive exact and approximate expressions for the probability of bit error, as well as the asymptotic signal-to-interference+noise ratio (SINR) in the large system limit. The analysis suggests that over a wide range of channel parameters the OMU receiver can outperform both the decorrelator and the single-user MF and perform similarly to the linear MMSE receiver, despite not knowing the channel parameters.
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ISSN:0018-9448
1557-9654
DOI:10.1109/TIT.2003.815761