Open Access

Carrier Frequency Offset Estimation and I/Q Imbalance Compensation for OFDM Systems

EURASIP Journal on Advances in Signal Processing20072007:045364

https://doi.org/10.1155/2007/45364

Received: 18 October 2005

Accepted: 11 January 2007

Published: 25 March 2007

Abstract

Two types of radio-frequency front-end imperfections, that is, carrier frequency offset and the inphase/quadrature (I/Q) imbalance are considered for orthogonal frequency division multiplexing (OFDM) communication systems. A preamble-assisted carrier frequency estimator is proposed along with an I/Q imbalance compensation scheme. The new frequency estimator reveals the relationship between the inphase and the quadrature components of the received preamble and extracts the frequency offset from the phase shift caused by the frequency offset and the cross-talk interference due to the I/Q imbalance. The proposed frequency estimation algorithm is fast, efficient, and robust to I/Q imbalance. An I/Q imbalance estimation/compensation algorithm is also presented by solving a least-square problem formulated using the same preamble as employed for the frequency offset estimation. The computational complexity of the I/Q estimation scheme is further reduced by using part of the short symbols with a little sacrifice in the estimation accuracy. Computer simulation and comparison with some of the existing algorithms are conducted, showing the effectiveness of the proposed method.

Keywords

Estimation AlgorithmOrthogonal Frequency Division MultiplexCarrier FrequencyEstimation AccuracyCompensation Scheme

[1234567891011121314151617181920]

Authors’ Affiliations

(1)
Centre for Signal Processing and Communications, Department of Electrical and Computer Engineering, Concordia University, Montreal, Canada

References

  1. Heiskala J, Terry J: OFDM Wireless LANs: A Theoretical and Practical Guide. SAMS, Indianapolis, Indiana; 2002.Google Scholar
  2. Van De Beek J-J, Sandell M, Börjesson PO: ML estimation of time and frequency offset in OFDM systems. IEEE Transactions on Signal Processing 1997,45(7):1800-1805. 10.1109/78.599949View ArticleMATHGoogle Scholar
  3. Minn H, Bhargava VK, Letaief KB: A robust timing and frequency synchronization for OFDM systems. IEEE Transactions on Wireless Communications 2003,2(4):822-839.View ArticleGoogle Scholar
  4. Lashkarian N, Kiaei S: Class of cyclic-based estimators for frequency-offset estimation of OFDM systems. IEEE Transactions on Communications 2000,48(12):2139-2149. 10.1109/26.891224View ArticleGoogle Scholar
  5. Ma X, Tepedelenlioǧlu C, Giannakis GB, Barbarossa S: Non-data-aided carrier offset estimators for OFDM with null subcarriers: identifiability, algorithms, and performance. IEEE Journal on Selected Areas in Communications 2001,19(12):2504-2515. 10.1109/49.974615View ArticleGoogle Scholar
  6. Li J, Liu G, Giannakis GB: Carrier frequency offset estimation for OFDM-based WLANs. IEEE Signal Processing Letters 2001,8(3):80-82. 10.1109/97.905946View ArticleGoogle Scholar
  7. Coulson AJ: Maximum likelihood synchronization for OFDM using a pilot symbol: algorithms. IEEE Journal on Selected Areas in Communications 2001,19(12):2486-2494. 10.1109/49.974613View ArticleGoogle Scholar
  8. Valkama M, Renfors M, Koivunen V: Advanced methods for I/Q imbalance compensation in communication receivers. IEEE Transactions on Signal Processing 2001,49(10):2335-2344. 10.1109/78.950789View ArticleGoogle Scholar
  9. Xing G, Shen M, Liu H: Frequency offset and I/Q imbalance compensation for OFDM direct-conversion receivers. Proceedings of IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP '03), April 2003, Hong Kong 4: 708-711.Google Scholar
  10. Liu C-L: Impacts of I/Q imbalance on QPSK-OFDM-QAM detection. IEEE Transactions on Consumer Electronics 1998,44(3):984-989. 10.1109/30.713223View ArticleGoogle Scholar
  11. Ma VK-P, Ylamurto T: Analysis of IQ imbalance on initial frequency offset estimation in direct down-conversion receivers. Proceedings of the 3rd IEEE Workshop on Signal Processing Advances in Wireless Communications (SPAWC '01), March 2001, Taiwan, China 158-161.Google Scholar
  12. Valkama M, Renfors M, Koivumen V: Compensation of frequency-selective I/Q imbalances in wideband receivers: models and algorithms. Proceedings of the 3rd IEEE Workshop on Signal Processing Advances in Wireless Communications (SPAWC '01), March 2001, Taiwan, China 42-45.Google Scholar
  13. Wright AR, Naylor PA: I/Q mismatch compensation in zero-IF OFDM receivers with application to DAB. Proceedings of IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP '03), April 2003, Hong Kong 2: 329-332.Google Scholar
  14. Tubbax J, Come B, Van der Perre L, Deneire L, Donnay S, Engels M: Compensation of IQ imbalance in OFDM systems. Proceedings of International Conference on Communications (ICC '03), May 2003, Anchorage, Alaska, USA 5: 3403-3407.Google Scholar
  15. Shaflee H, Fouladifard S: Calibration of IQ imbalance in OFDM transceivers. Proceedings of IEEE International Conference on Communications (ICC '03), May 2003, Seattle, Wash, USA 3: 2081-2085.Google Scholar
  16. Gaudes CC, Valkama M, Renfors M: A novel frequency synthesizer concept for wireless communications. Proceedings of IEEE International Symposium on Circuits and Systems (ISCAS '03), May 2003, Bangkok, Thailand 2: 85-88.Google Scholar
  17. Tubbax J, Fort A, Van der Perre L, et al.: Joint compensation of IQ imbalance and frequency offset in OFDM systems. Proceedings of IEEE Global Telecommunications Conference (GLOBECOM '03), December 2003, San Francisco, Calif, USA 4: 2365-2369.View ArticleGoogle Scholar
  18. Fouladifard S, Shafiee H: Frequency offset estimation in OFDM systems in presence of IQ imbalance. Proceedings of the 8th International Conference on Communication Systems (ICCS '02), November 2002, Amsterdam, The Netherlands 1: 214-218.Google Scholar
  19. Tubbax J, Van der Perre L, Donnay S, Engels M, Moonen M, De Man H: Joint compensation of IQ imbalance, frequency offset and phase noise in OFDM receivers. European Transactions on Telecommunications 2004,15(3):283-292. 10.1002/ett.974View ArticleGoogle Scholar
  20. Abidi AA: Direct-conversion radio transceivers for digital communications. IEEE Journal of Solid-State Circuits 1995,30(12):1399-1410. 10.1109/4.482187View ArticleGoogle Scholar

Copyright

© Feng Yan et al. 2007

This article is published under license to BioMed Central Ltd. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Advertisement