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Analysis and Design of Timing Recovery Schemes for DMT Systems over Indoor Power-Line Channels

Abstract

Discrete multitone (DMT) modulation is a suitable technique to cope with main impairments of broadband indoor power-line channels: spectral selectivity and cyclic time variations. Due to the high-density constellations employed to achieve the required bit-rates, synchronization issues became an important concern in these scenarios. This paper analyzes the performance of a conventional DMT timing recovery scheme designed for linear time-invariant (LTI) channels when employed over indoor power lines. The influence of the channel cyclic short-term variations and the sampling jitter on the system performance is assessed. Bit-rate degradation due to timing errors is evaluated in a set of measured channels. It is shown that this synchronization mechanism limits the system performance in many residential channels. Two improvements are proposed to avoid this end: a new phase error estimator that takes into account the short-term changes in the channel response, and the introduction of notch filters in the timing recovery loop. Simulations confirm that the new scheme eliminates the bit-rate loss in most situations.

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Correspondence to José Antonio Cortés.

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Open Access This article is distributed under the terms of the Creative Commons Attribution 2.0 International License (https://doi.org/creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Cortés, J.A., Díez, L., Martos-Naya, E. et al. Analysis and Design of Timing Recovery Schemes for DMT Systems over Indoor Power-Line Channels. EURASIP J. Adv. Signal Process. 2007, 048931 (2007). https://doi.org/10.1155/2007/48931

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Keywords

  • Phase Error
  • Measured Channel
  • Notch Filter
  • Channel Response
  • Cyclic Time