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

The Korean Institute of Commucations and Information Sciences (한국통신학회)
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A New Fast Wavelet Transform Based Adaptive Algorithm for OFDM Adaptive Equalizer and its VHDL Implementation

OFDM 적응 등화기 성능향상을 위한 새로운 고속 웨이블렛 기반 적응 알고리즘 및 VHDL 구현

  • 정민수 (대구대학교 정보통신공학과 신호처리 연구실) ;
  • 이재균 (대구대학교 정보통신공학과 신호처리 연구실) ;
  • 이채욱 (대구대학교 정보통신공학과 신호처리 연구실)
  • Published : 2006.11.30
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Abstract

Data transmission experiences multiplicative distortion in frequency nonselective fading channel. This distortion occurs in OFDM communication channel and can be compensated using an equalizer. Usually, in the case of LMS equalizer, eigenvalue distribution of training signal is enlarged. Large eigenvalue distribution causes principally the performance of a communication system to be deteriorated. This paper proposes a new algorithm that shows the same performance as the existing fast wavelet transform algorithm with less computational complexity. The proposed algorithm was applied to an adaptive equalizer of OFDM communication system. Matlab simulation results show a better performance than the existing one. The proposed algorithm was implemented in VHDL and simulated.

주파수 비선택적 페이딩 채널에서의 데이터 전송은 승산성 왜곡으로부터 영향을 받는다 OFDM 방식에서도 채널의 영향에 의해 이러한 왜곡이 발생하게 되며 이를 보상하기 위해 등화기를 사용한다. 일반적으로 LMS 알고리즘을 사용한 적응 등화기의 경우 시변 채널을 거친 훈련신호의 고유치 분포가 커지게 된다. 고유값 분포가 커지면 통신시스템의 성능을 저하시키는 주요한 원인이 된다. 본 논문에서는 기존의 wavelet 변환을 고속으로 처리하는 고속화 알고리즘과 비교하여 적은 계산량으로 동일한 성능을 보이는 새로운 고속화 알고리즘을 제안한다 제안한 알고리즘을 OFDM 통신시스템의 적응등화기에 적용하였다. 기존의 알고리즘과 비교 및 분석한 결과 제안한 알고리즘의 성능이 우수한 것을 알 수 있었다. 제안한 알고리즘을 VHDL로 구현하였다.

Keywords

References

  1. Gray, A.A Hoy, S.D. Ghuman, P., 'Adaptive LMS processing architectures employing frequency domain sub-convolution,' Circuits and Systems 2004, Proceedings of the 2004 International Symposium on. Vol. 3, 23-26, May 2004
  2. Jiangtao Xi and J. F. Chicharo, 'Computing running discrete cosine/sine transform based on the adaptive LMS algorithm,' Circuits and Systems for Video Technology, IEEE Transactions on , Vol. 8, Issue. 1, pp. 31-35, Feb, 1998
  3. Junghsi Lee & Sheng-chieh Chang, 'On the convergence properties of multidelay frequency domain adaptive filter,' Proceedings of the 1999 IEEE International Conference on Acoustics Speech and Signal Processing Volume 4, 1865-1868, March, 1999
  4. Kostas Berberidis & Sergios Theodoridis, 'A new fast block adaptive algorithm,' IEEE Transactions on Signal Processing, vol.47, no.1, January, 1999
  5. Wasfy B.Mikhael & Andreas S.Spanias, 'A fast frequency-domain adaptive algorithm,' Proceedings of the IEEE, vol.76, no.1, January, 1988
  6. G. A. Clark, S. K. Mitra and S. R. Parker,' Block implementation of adaptive digital filters', IEEE Transactions on Circuits and Systems, Vol.36, No.2, pp.173-189, Feb., 1989 https://doi.org/10.1109/31.20196
  7. W.K.Jenkins and J.R.Kreidle, 'Adaptive digital filters using the Walsh-Hadamard transform,' on Circuits and Systems, San Jose, CA, pp.875-878, May, 1986
  8. R.W. Chang, 'Synthesis of band-limited orthogonal signals for multi-channel data transmission,' Bell system Tech, Journal Vol. 45, pp.1775-1796, Dec., 1996
  9. P.H.Moose, 'A technique for orthogonal frequency division multiplexing frequency offset correction,' IEEE Trans. Comm. Vol. 42, no. 10, pp. 2908-2914, Oct., 1994 https://doi.org/10.1109/26.328961
  10. T.N.Zogakis and J.M.Cioffi, 'The effect of timing jitter on the performance of a discrete multione system,' IEEE Trans. comm. Vol. 44, no.7, pp.799-808, July, 1996 https://doi.org/10.1109/26.508299
  11. L.C.Cimini Jr. 'Analysis and simulation of a digital mobile channel using orthogonal frequency division multiplexing,' IEEE Trans. Comm. Vol. 33, no.7, pp.665-675, July, 1985 https://doi.org/10.1109/TCOM.1985.1096357