대한전자공학회논문지TC (Journal of the Institute of Electronics Engineers of Korea TC)

대한전자공학회 (The Institute of Electronics and Information Engineers)
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QAM 변조방식의 OFDM 시스템을 위한 결정지향 채널추정 방법

Decision-directed Channel Estimation for QAM-modulated OFDM Systems

  • 임민중 (東國大學校 情報通信工學科) ;
  • 안재민 (忠南大學校 情報通信工學部) ;
  • 김연수 (韓國通信 서비스開發硏究所)
  • Rim, Min-Joong (Department of Information and Communication Engineering, Dongguk University) ;
  • Ahn, Jae-Min (School of Electrical and Computer Engineering, Chungnam National University) ;
  • Kim, Yeon-Soo (Service Development Lab., Korea Telecom)
  • 발행 : 2002.11.01
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초록

QAM-OFDM 시스템에서 결정지향 채널추정을 위해 사용하는 2차원 필터의 최적의 크기와 모양은 도플러 주파수, 신호의 지연확산, 신호 대 잡음비 등 채널의 특성과 함께 송신 심벌의 크기에 의해서 결정된다. 기존의 채널 추정방법들은 QAM 변조 방식에서의 송신 심벌의 크기의 다양성을 고려하지 않고 채널 특성만을 고려한 고정된 형태의 필터를 취하는 데 반해서 이 논문에서는 단순하면서도 송신 심벌의 크기의 다양성을 고려한 필터를 제안한다. 제안된 채널추정방법은 작은 크기의 필터로 예측잡음을 효과적으로 줄일 수 있으므로 구현 복잡도를 줄일 수 있는 가능성을 가질 뿐만 아니라 채널의 변화에 의한 성능 감소 효과도 적어 더 우수한 성능을 나타낼 수 있다.

When decision-directed channel estimation is used for QAM-OFDM systems, the optimal shape of the two-dimensional filter depends on the amplitudes of the modulated symbols as well as the channel characteristics such as delay spread, Doppler frequency, and signal-to-noise ratio. While most conventional channel estimation methods did not consider the amplitudes of the modulated symbols because of the large computational complexity, we propose a simple channel estimation method for multi-level-amplitude-modulated systems. The proposed method can effectively reduce the noise variance of the estimates with small-sized filtering and there is a possibility of reducing the implementation cost and producing better results by avoiding the bias due to large filter sizes.

키워드

참고문헌

  1. Z. Wang, G. B. Giannakis, 'Wireless Multicarrier Communications,' IEEE Signal Processing Magazine, May 2000 https://doi.org/10.1109/79.841722
  2. Y. Li, N. R. Sollenberger, 'Adaptive Antenna Arrays for OFDM Systems with Cochannel Interference,' IEEE Trans. On Communication, pp. 217-229, February 1999 https://doi.org/10.1109/26.752127
  3. J-J. van de Beek, O. Edfors, M. Sandell, S. K. Wilson, and P. O. Borjesson, 'On channel estimation in OFDM systems,' in Proc. IEEE Vehicular Technology Conf., pp. 815-819, July 1995 https://doi.org/10.1109/VETEC.1995.504981
  4. O. Edfors, M. Sandel, J-J. van de Beek, S. K. Wildon, and P. O. Borjesson, 'OFDM Channel Estimation by Singular Value Decomposition,' IEEE Trans. On Communication, pp. 931-939, July 1998 https://doi.org/10.1109/26.701321
  5. Y. Li, L. J. Cimini, N. R. Sollenberger, 'Robust Channel Estimation for OFDM Systems with Rapid Dispersive Fading Channels,' IEEE Trans. On Communication, pp. 902-915, July 1998 https://doi.org/10.1109/26.701317
  6. Y. LI, N. Seshadri, S. Ariyavisitakul, 'Channel Estimation for OFDM Systems with Transmitter Diversity in Mobile Wireless Channels,' IEEE Journal on Selected Areas in Communication, pp. 461-471, March 1999 https://doi.org/10.1109/49.753731
  7. Y. Li, 'Pilot-Symbol-Aided Channel Estimation for OFDM in Wireless Systems,' IEEE Trans. On Vehicular Technology, pp. 1207-1215, July 2000 https://doi.org/10.1109/25.875230
  8. J. Rinne and M. Renfors, 'Pilot Spacing in Orthogonal Frequency Division Multiplexing Systems on Practical Channels,' IEEE Trans. On Consumer Electronics, November 1996 https://doi.org/10.1109/30.555792
  9. R. Nilsson, O. Edfors, M. Sandell, P. O. Borjesson, 'An Analysis of Two-Dimensional Pilot-Symbol Assisted Modulation for OFDM,' ICPWC, 1997 https://doi.org/10.1109/ICPWC.1997.655481
  10. P. K. Frenger, N. A. B. Svensson, 'Decision-Directed Coherent Detection in Multicarrier Systems on Rayleigh Fading Channels,' IEEE Trans. On Vehicular Technology, pp. 490-498, March 1999 https://doi.org/10.1109/25.752573
  11. A. Chini, Y. Wu, M. El-Tanany, and S. Mahmoud, 'Filtered Decision Feedback Channel Estimation for OFDM-based Terrestrial Broadcasting System,' IEEE Trans. On Broadcasting, pp. 2-11, March 1998 https://doi.org/10.1109/11.713051
  12. L. L. Scharf, Statistical Signal Processing, Addison-Wisely, 1991
  13. G. Li, Y. Jin, 'A Speed Estimation Based Two-Stage Symbol Aided Channel Estimator for Frequency Nonselective Variant Fading Channel,' Personal Wireless Communications, pp. 109-113, 2000 https://doi.org/10.1109/ICPWC.2000.905783
  14. H.J. Oh, J.M. Cioffi, 'An Adaptive Channel Estimation Scheme for DS-CDMA Systems,' VTC, pp. 2839-2843, 2000 https://doi.org/10.1109/VETECF.2000.886837
  15. 이영용, 배광석, 안재민, 임민중, 최형진, '속도 추정기를 갖는 WCDMA 역방향 링크 수신기를 위한 비대칭 직접 판별 채널 추정기,' pp. 391-394, JCCI, 2001