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  • Research Article
  • Open Access

Cholesky Factorization-Based Adaptive BLAST DFE for Wideband MIMO Channels

  • 1Email author,
  • 2 and
  • 1
EURASIP Journal on Advances in Signal Processing20072007:045789

  • Received: 11 October 2006
  • Accepted: 23 February 2007
  • Published:


Adaptive equalization of wireless systems operating over time-varying and frequency-selective multiple-input multiple-output (MIMO) channels is considered. A novel equalization structure is proposed, which comprises a cascade of decision feedback equalizer (DFE) stages, each one detecting a single stream. The equalizer filters, as well as the ordering by which the streams are extracted, are updated based on the minimization of a set of least squares (LS) cost functions in a BLAST-like fashion. To ensure numerically robust performance of the proposed algorithm, Cholesky factorization of the equalizer input autocorrelation matrix is applied. Moreover, after showing that the equalization problem possesses an order recursive structure, a computationally efficient scheme is developed. A variation of the method is also described, which is appropriate for slow time-varying conditions. Theoretical analysis of the equalization problem reveals an inherent numerical deficiency, thus justifying our choice of employing a numerically robust algebraic transformation. The performance of the proposed method in terms of convergence, tracking, and bit error rate (BER) is evaluated through extensive computer simulations for time-varying and wideband channels.


  • MIMO Channel
  • Equalization Problem
  • Cholesky Factorization
  • Recursive Structure
  • Autocorrelation Matrix

Authors’ Affiliations

Department of Computer Engineering & Informatics/C.T.I.-R&D, University of Patras, Rio-Patras, 26500, Greece
Institute for Space Applications and Remote Sensing, National Observatory of Athens, Palea Penteli, Athens, 15236, Greece


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© Vassilis Kekatos et al. 2007

This article is published under license to BioMed Central Ltd. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.