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

The Korean Institute of Commucations and Information Sciences (한국통신학회)
권호 표지

Blind OFDM Synchronization Algorithm using Cyclic Correlation

순환상관(Cyclic Correlation)을 이용한 OFDM 시스템에서의 블라인드 동기 알고리즘

  • 박병준 (연세대학교 전기전자공학과 정보통신 연구실) ;
  • 고은석 (연세대학교 전기전자공학과 정보통신 연구실) ;
  • 강창언 (연세대학교 전기전자공학과 정보통신 연구실) ;
  • 홍대식 (연세대학교 전기전자공학과 정보통신 연구실)
  • Published : 2005.01.01
Download PDF
⟨ Previous Next ⟩

Abstract

In this paper, blind synchronization algorithm is developed for estimating jointly timing and frequency offset of OFDM system. The proposed estimator exploits the second-order cyclostationarity of received signals, and then uses the information of symbol timing and carrier frequency offset appeared in the cyclic correlation. As a bling estimator, the information of impulse response of channel and training symbols are not required. The performance of the proposed method is consistent in spite of channel conditions in mean squre error sense, and simulation results prove it. For more accurate estimaion, the method that averages cyclic correlation is applied. In this case, the performance of averaging method is better.

본 논문에서는 OFDM 시스템의 시간 오차와 주파수 오차를 추정하는 방안을 제시하고 있다. 제안한 동기 알고리즘은 수신 신호의 순환상괸(cyclic correlation)을 이용하며, 이 순환상관에는 시간과 주파수 오차 정보가 모두 나타나게 된다. 따라서 제안하는 추정 알고리즘은 여분의 학습심볼(training symbol)를 필요로 하지 않으며, 채널의 정보를 사용하지 않는다. 제안한 추정 방법은 평균자승오차(mean square error) 성능에서 잡음이나 채널의 특성에 상관없이 거의 일정한 성능을 가지며, 실험 결과는 이러한 특징을 뒷받침 해주고 있다. 좀 더 정확한 추정을 위해서, 순환 상관을 평균을 취하는 방법이 적용되었다. 이 경우, 평균을 취하는 방법은 평균을 취하지 않는 방법보다 훨씬 더 정확한 추정을 가능하게 한다.

Keywords

References

  1. ETSI, 'Radio broadcast systems; digital audio broadcasting (DAB) to mobile, portable and fixed receives : Final draft pr ETS 300 401,' European Telecommunications Standards Institute, Nov. 1994
  2. Hikmet Sari, Georges Karam and Isabelle Jeanclaude, 'Transmission techniques for digital terrestrial TV broadcasting,' IEEE Commun. Mag., vol. 33, pp.100-109, Feb. 1995
  3. K. Pahlavan, A. Zahedi and P. Krishnamurthy, 'Wideband local access : Wireless LAN and wireless ATM,' IEEE Commun. Mag., vol. 35, pp. 34-40, Nov. 1997
  4. T.M. Schmidl and D.C. Cox, 'Robust Frequency and Timing Synchronization for OFDM,' IEEE Trans. Commun., vol. 45, pp. 1613-1621, December 1997 https://doi.org/10.1109/26.650240
  5. Paul H. Moose, 'A Technique for Orthogonal Frequency Division Multiplexing Frequency Offset Correction,' IEEE Trans. Commun., vol. 42, pp. 2908-2914, October 1994 https://doi.org/10.1109/26.328961
  6. Taekwan Kim, Namshin Cho, Jaehee Cho, Keukjoon Bang, Kwangchul Kim, Hyunchoil Park and Daesik Hong, 'A Fast Burst Synchronization for OFDM Based Wireless Asynchronous Transfer Mode Systems,' Globecom'99, pp. 543-547, 1999
  7. Keukjoon Bang, Namshin Cho, Jaehee Cho, Heeyoung Jun, Kwangchul Kim, Hyuncheol Park, Daesik Hong, 'A coarse frequency offset estimation in an OFDM system using the concept of the coherence phase bandwidth,' IEEE Trans. Commun., vol. 49, pp. 1320 -1324, August 2001 https://doi.org/10.1109/26.939841
  8. J.J. van de Beek, M. Sandell and P.O. Borjesson, 'ML estimation of Time and Frequency Offset in OFDM Systems,' IEEE Trans. Signal Processing, vol. 43, pp. 761-766, August 1997
  9. Fulvio Gini and Georgios B. Giannakis, 'Frequency Offset and Symbol Timing Recovery in Hat-Fading Channels: A Cyclostationarity Approach,' IEEE Trans. Commun., vol. 46, pp. 400-411, March 1998 https://doi.org/10.1109/26.662646
  10. Helmut Bolcskei, 'Blind Estimation of Symbol Timing and Carrier Frequency Offset in Wireless OFDM Systems,' IEEE Trans. Commun., vol. 49, pp. 988-999, June 2001 https://doi.org/10.1109/26.930629
  11. William A. Gardner, 'Exploitation of spectral redundancy in cyclostationary signals,' IEEE Signal Processing Mag., vol. 8, pp. 14-36, Apr. 1991