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Frequency domain concurrent channel equalization for multicarrier systems

Abstract

Receivers for wireless Orthogonal Frequency Division Multiplexing (OFDM) systems usually perform the channel estimation based on pilot carriers in known positions of the channel spectrum. Interpolation between pilot carriers is applied to determine the channel transfer function in all carrier frequencies. Channel variations along time are compensated by means of interpolation between successive channel estimates on the same carrier frequency. However, not rarely, the fast channel variations exceed the time interpolator capability, as is the case for mobile operation. In this article we present a new channel compensation technique based on the concurrent operation of two stochastic gradient timedomain algorithms, one which minimizes a cost function that measures the received signal energy dispersion and other which minimizes the Euclidean distance between the received digital modulation symbols and the ones in the reference constellation assigned to each OFDM sub-channel. Results show that the new technique advantageously improves the system robustness to fast channel variations since, with a low computational cost, it dramatically reduces the demodulator symbol error rate even when the receiver is operating in an intense dynamic multipath scenario.

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Open Access This article is distributed under the terms of the Creative Commons Attribution 2.0 International License ( https://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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D’Agostini, F., Júnior, S.C., De Castro, M.C.F. et al. Frequency domain concurrent channel equalization for multicarrier systems. J Braz Comp Soc 13, 7–16 (2007). https://doi.org/10.1007/BF03192397

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  • DOI: https://doi.org/10.1007/BF03192397

Keywords

  • Concurrent
  • Equalization
  • Broadcast
  • Modulation
  • Pilots
  • Multicarrier