DocumentCode :
3325500
Title :
Optimal multiuser CDMA decoder using grouped coordinate ascent and the DWT
Author :
Sharfer, Llan ; Hero, Alfred O.
Author_Institution :
Dept. of Electr. Eng. & Comput. Sci., Michigan Univ., Ann Arbor, MI, USA
fYear :
1997
fDate :
16-18 April 1997
Firstpage :
137
Lastpage :
140
Abstract :
It is well known that direct implementation of the optimal multiuser receiver for an asynchronous code division multiple access (CDMA) communication system has an exponential complexity in the number of users. We present an iterative implementation of an optimal multiuser receiver which has at most cubic complexity per iteration in the number of users. The receiver performs joint maximum likelihood (ML) estimation of the amplitudes, phases, time delays, and symbol sequences of all the users. Similar, to the single user receiver we presented by Sharfer and Hero (see Proc. ICASSP, 1996), the multiuser receiver is based on a signal decomposition with respect to a compactly supported orthonormal wavelet basis. The algorithm uses grouped coordinate ascent updates to increase the likelihood function in each iteration. Simulation results of a two user system are presented showing that the receiver is near-far resistant, and attains the single user bit error probability bound.
Keywords :
amplitude estimation; code division multiple access; coding errors; decoding; delays; error statistics; estimation theory; iterative methods; maximum likelihood estimation; phase estimation; pseudonoise codes; radio receivers; spread spectrum communication; telecommunication channels; transforms; wavelet transforms; CDMA communication system; DWT; amplitude estimation; asynchronous code division multiple access; bit error simulation results; exponential complexity; grouped coordinate ascent; grouped coordinate ascent updates; iterative implementation; joint maximum likelihood estimation; likelihood function; near-far resistant receiver; optimal multiuser CDMA decoder; optimal multiuser receiver; orthonormal wavelet basis; phase estimation; pseudonoise sequence; signal decomposition; single user bit error probability bound; symbol sequences; time delay estimation; Amplitude estimation; Delay effects; Delay estimation; Error probability; Iterative decoding; Maximum likelihood decoding; Maximum likelihood estimation; Multiaccess communication; Phase estimation; Signal resolution;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Signal Processing Advances in Wireless Communications, First IEEE Signal Processing Workshop on
Conference_Location :
Paris, France
Print_ISBN :
0-7803-3944-4
Type :
conf
DOI :
10.1109/SPAWC.1997.630177
Filename :
630177
Link To Document :
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