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International Journal of Digital Multimedia Broadcasting
Volume 2014 (2014), Article ID 987039, 10 pages
Research Article

Decision Feedback Blind Equalizer with Tap-Leaky Whitening for Stable Structure-Criterion Switching

1“Mihajlo Pupin” Institute, Volgina 15, 11060 Belgrade, Serbia
2Singidunum University, Danijelova 29, 11000 Belgrade, Serbia

Received 29 July 2014; Revised 4 December 2014; Accepted 11 December 2014; Published 31 December 2014

Academic Editor: Massimiliano Laddomada

Copyright © 2014 Vladimir R. Krstić and Miroslav L. Dukić. 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.


The research presented in this paper improves the structure-criterion switching performance of the blind decision feedback equalizer (DFE) which eliminates error propagation effects by optimizing both the structure and the cost criterion. To conquer the complexity of the 64-QAM (quadrature amplitude modulated) signal constellation, the stochastic entropy-gradient algorithm is additionally regularized by the coefficient leaky term to avoid a coefficients norm overgrowth of the received signal whitener. Effectively, the leak of coefficients is employed to ensure a stable structure-criterion switching of DFE between blind and decision-directed operation modes. The optimization of the resulting whitening algorithm is achieved by means of two free, leaky and entropic, parameters which act in opposition to each other. Both, the influence of the 64-QAM signal on the feedback filter behavior and the parametric optimization of the whitening algorithm are analyzed through simulations.