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Proceedings Paper

Signal processing for multiuser wireless systems on reconfigurable platforms
Author(s): Joseph Thomas
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Paper Abstract

Iterative multiuser decoding (IMD) is a suboptimal reception technique that yields near-optimal performance via the iterative exchange of soft information between a (multiuser) demodulator and a bank of single-user soft decoders to their mutual benefit. From a practical perspective, using the minimum mean square error (MMSE) multiuser interference suppressor for demodulation yields good performance and near-far resistance over a wide range of received signal powers, in both additive white Gaussian noise and dispersive fading channels. The computational issues and system tradeoffs, involved in realizing MMSE-IMD receivers on reconfigurable platforms, at base stations in the multicell code-division multiple access (CDMA) uplink, are considered in this paper. In particular, an approximation is proposed, to reduce the complexity of the most computationally intensive task in the receiver, viz., the inversion of a matrix of dimensions proportional to the product of the spreading factor and the receiver sensor-count; this approximation is observed to degrade system performance only marginally. A suitable partitioning of the receiver's computational tasks between software- and hardware-configurable platforms is also proposed. This is followed by a study of the performance-complexity tradeoffs among various system design options (such as the iteration-count, receiver sensor-count, and choice of soft decoding algorithm) in such rapidly configurable environments, and their impact on system capacity. It is inferred that actual realizations of the MMSE-IMD can indeed provide vast performance gains over existing suboptimal receivers.

Paper Details

Date Published: 24 July 2001
PDF: 12 pages
Proc. SPIE 4525, Reconfigurable Technology: FPGAs and Reconfigurable Processors for Computing and Communications III, (24 July 2001); doi: 10.1117/12.434380
Show Author Affiliations
Joseph Thomas, Univ. of Maryland/College Park (United States)

Published in SPIE Proceedings Vol. 4525:
Reconfigurable Technology: FPGAs and Reconfigurable Processors for Computing and Communications III
John Schewel; Peter M. Athanas; Philip B. James-Roxby; John T. McHenry, Editor(s)

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