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A Variable Leaky Entropy-Based Whitening Algorithm for Blind Decision Feedback Equalization

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Abstract

This paper addresses the joint entropy maximization algorithm constrained by the variable leaky factor (JEM-VL) aiming at mitigating the feedback filter (FBF) mismatch effects characterizing the operation of the decision feedback equalizer which, at the start of adaptation, swaps positions of feedforward and feedback filters so that the latter acts as a linear all-pole whitener of the received signal. The FBF mismatch is a result of disparity between the FBF setup achieved in the blind mode by observing channel outputs and an excepted FBF setup in the tracking mode which is driven by detected data symbols. Depending on the given signal complexity and inter-symbol interference severity, the FBF filter mismatch is typically manifested by the equalizer convergence instability or even the catastrophic error propagation effects arising at the time of the equalizer structure-criterion switching from the blind to the tracking operation mode. The constraint of superfluous coefficients of the FBF filter by means of the JEM-VL algorithm eliminates the equalizer convergence instability at the time of its switching and, consequently, increases equalization successfulness. The efficiency of the JEM-VL algorithm is verified by simulations using the 64-QAM signal.

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Notes

  1. The hypothesis of correctness of previous detected symbols is commonly use in the DFE analysis.

  2. Although the outputs z n are not noise free, the noiseless system model is assumed in order to simplify the derivation of the JEM algorithm. In simulations presented in the paper we have used more realistic noisy channels.

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Acknowledgments

This work was supported by the Ministry of Science and Technological Development of the Republic of Serbia; the project of technological development TR 32037, 2011–2016.

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Authors and Affiliations

  1. “Mihajlo Pupin” Institute, University of Belgrade, Volgina 15, Belgrade, 11060, Serbia

    Vladimir R. Krstić

  2. Astel Project, Kraljice Natalije 38, Belgrade, 11000, Serbia

    Aco M. Stevanović

  3. Technical Faculty “Mihajlo Pupin” Zrenjanin, University of Novi Sad, Novi Sad, Serbia

    Borislav Lj. Odadžić

Authors
  1. Vladimir R. Krstić
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  2. Aco M. Stevanović
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  3. Borislav Lj. Odadžić
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Correspondence to Vladimir R. Krstić.

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Krstić, V.R., Stevanović, A.M. & Odadžić, B.L. A Variable Leaky Entropy-Based Whitening Algorithm for Blind Decision Feedback Equalization. Wireless Pers Commun 95, 931–946 (2017). https://doi.org/10.1007/s11277-016-3806-7

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  • DOI: https://doi.org/10.1007/s11277-016-3806-7

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