The Journal of Korean Institute of Communications and Information Sciences (한국통신학회논문지)

The Korean Institute of Commucations and Information Sciences (한국통신학회)
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An Optimization Algorithm for Blind Channel Equalizer Using Signal Estimation Reliability

신호 추정 신뢰도를 활용한 블라인드 채널 등화기 최적화 알고리즘

  • 오길남 (광주대학교 광통신공학과)
  • Received : 2013.02.12
  • Accepted : 2013.04.08
  • Published : 2013.04.30
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Abstract

For blind channel equalization, the reliability of signal estimate determines the convergence speed and steady-state performance of the equalizer. Therefore the nonlinear estimator and reference signal being used in signal estimate should be chosen appropriately. In this paper, to increase the reliability of the signal estimate, two errors were obtained by applying coarse signal points and dense signal points respectively to signal estimate, the relative reliabilities of two errors were calculated, then the equalizer was adapted deferentially utilizing the reliabilities. At this point, by applying two errors alternately, two modes of operation were smoothly combined. Through computer simulations the proposed method was confirmed to achieve fast transient state convergence and low steady-state error compared to traditional methods.

블라인드 채널 등화 시 신호 추정의 신뢰도는 등화기의 수렴 속도와 정상상태 성능을 결정한다. 그러므로 신호 추정에 사용되는 비선형 추정기와 기준 신호가 적절히 선택되어야 한다. 이 논문에서는 신호 추정의 신뢰도를 높이기 위해 신호 추정에 성긴 신호점과 촘촘한 신호점을 각각 적용하여 두 오차를 구하고, 두 오차의 상대적 신뢰도를 산출, 이를 활용하여 등화기를 차등적으로 적응시켰다. 이때 두 오차를 번갈아 적용하여 두 동작 모드를 완만하게 결합하였다. 모의실험을 통하여 제안 방식이 기존 방식에 비해 빠른 과도상태 수렴과 낮은 정상상태 오차를 달성하는 것을 보였다.

Keywords

References

  1. Y. Sato, "A method of self-recovering equalization for multilevel amplitude modulation systems," IEEE Trans. Commun., vol. 23, no. 6, pp. 679-682, June 1975. https://doi.org/10.1109/TCOM.1975.1092854
  2. J. R. Treichler and B. G. Agee, "A new approach to multipath correction of constant modulus signals," IEEE Trans. Acoust., Speech, Signal Process., vol. ASSP-31, no. 2, pp. 459-472, Apr. 1983.
  3. S. Fiori, "Analysis of modified "Bussgang" algorithms (MBAs) for channel equalization," IEEE Trans. Circuits Syst. I, vol. 51 no. 8, pp. 1552-1560, Aug. 2004.
  4. D.N. Godard and P.E. Thirion, "Method device for training an adaptive equalizer by means of an unknown data signal in a QAM transmission system," U.S. Patent 4 227 152, Oct. 7, 1980.
  5. J. G. Proakis and M. Salehi, Digital Communications, 5th Ed., McGraw-Hill, 2008.
  6. O. Macchi and E. Eweda, "Convergence analysis of self-adaptive equalizers," IEEE Trans. Inform. Theory, vol. IT-30, no. 2, pp. 161-176, Mar. 1984.
  7. C. A. R. Fernandes, G. Favier, and J. C. M. Mota, "Decision directed adaptive blind equalization based on the constant modulus algorithm," Signal, Image Video Process. (SIViP), vol. 1, no. 4, pp. 333-346, July 2007. https://doi.org/10.1007/s11760-007-0027-2
  8. X.-W. Zhang and W. Rao, "New concurrent blind equalization algorithm suitable for high-order QAM signals," 5th Int. Conf. FSKD '08, vol. 2, pp. 177-181, Shandong, China, Oct. 2008.
  9. W. Rao, W. Tan, Y. Li, and H. Gao, "New modified constant modulus algorithm for underwater acoustic communications," ICICIS '11, pp. 563-566, Hong Kong, Sep. 2011.