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Joint Compensation of OFDM Frequency-Selective Transmitter and Receiver IQ Imbalance

Abstract

Direct-conversion architectures are recently receiving a lot of interest in OFDM-based wireless transmission systems. However, due to component imperfections in the front-end analog processing, such systems are very sensitive to in-phase/quadrature-phase (IQ) imbalances. The IQ imbalance results in intercarrier interference (ICI) from the mirror carrier of the OFDM symbol. The resulting distortion can limit the achievable data rate and hence the performance of the system. In this paper, the joint effect of frequency-selective IQ imbalance at both the transmitter and receiver ends is studied. We consider OFDM transmission over a time-invariant frequency-selective channel. When the cyclic prefix is long enough to accommodate the channel impulse response combined with the transmitter and receiver filters, we propose a low-complexity two-tap equalizer with LMS-based adaptation to compensate for IQ imbalances along with channel distortions. When the cyclic prefix is not sufficiently long, then in addition to ICI there also exists interblock interference (IBI) between the adjacent OFDM symbols. In this case, we propose a frequency domain per-tone equalizer (PTEQ) obtained by transferring a time-domain equalizer (TEQ) to the frequency domain. The PTEQ is initialized by a training-based RLS scheme. Both algorithms provide a very efficient post-FFT adaptive equalization and their performance is shown to be close to the ideal case.

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References

  1. IEEE standard 802.11a-1999: wireless LAN medium access control (MAC) & physical layer (PHY) specifications, highspeed physical layer in 5 GHz band 1999.

  2. Koffman I, Roman V: Broadband wireless access solutions based on OFDM access in IEEE 802.16. IEEE Communications Magazine 2002,40(4):96-103. 10.1109/35.995857

    Article  Google Scholar 

  3. ETSI Digital Video Broadcasting; Framing structure, Channel Coding & Modulation for Digital TV 2004.

  4. Baier A: Quadrature mixer imbalances in digital TDMA mobile radio receivers. Proceedings of the International Zurich Seminar on Digital Communications. Electronic Circuits and Systems for Communications, March 1990, Zurich, Switzerland 147-162.

    Google Scholar 

  5. Liu C-L: Impacts of I/Q imbalance on QPSK-OFDM-QAM detection. IEEE Transactions on Consumer Electronics 1998,44(3):984-989. 10.1109/30.713223

    Article  Google Scholar 

  6. Schuchert A, Hasholzner R, Antoine P: A novel IQ imbalance compensation scheme for the reception of OFDM signals. IEEE Transactions on Consumer Electronics 2001,47(3):313-318. 10.1109/30.964115

    Article  Google Scholar 

  7. Tubbax J, Côme B, Van Der Perre L, Donnay S, Moonen M, De Man H: Compensation of transmitter IQ imbalance for OFDM systems. Proceedings of IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP '04), May 2004, Montreal, Canada 2: 325-328.

    Google Scholar 

  8. Valkama M, Renfors M, Koivunen 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 

  9. Tarighat A, Bagheri R, Sayed AH: Compensation schemes and performance analysis of IQ imbalances in OFDM receivers. IEEE Transactions on Signal Processing 2005,53(8):3257-3268.

    MathSciNet  Article  Google Scholar 

  10. Tarighat A, Sayed AH: OFDM systems with both transmitter and receiver IQ imbalances. Proceedings of the 6th IEEE Workshop on Signal Processing Advances in Wireless Communications (SPAWC '05), June 2005, New York, NY, USA 735-739.

    Google Scholar 

  11. Tsui E, Lin J: Adaptive IQ imbalance correction for OFDM systems with frequency and timing offsets. Proceedings of IEEE Global Telecommunications Conference (GLOBECOM '04), November 2004, Dallas, Tex, USA 6: 4004-4010.

    Article  Google Scholar 

  12. van Acker K, Leus G, Moonen M, van de Wiel O, Pollet T: Per tone equalization for DMT-based systems. IEEE Transactions on Communications 2001,49(1):109-119. 10.1109/26.898255

    MATH  Article  Google Scholar 

  13. Tandur D, Moonen M: Joint compensation of OFDM transmitter and receiver IQ imbalance in the presence of carrier frequency offset. Proccedings of European Signal Processing Conference (EUSIPCO '06), September 2006, Florence, Italy

    Google Scholar 

  14. Tandur D, Moonen M: Joint adaptive compensation of transmitter and receiver IQ imbalance under carrier frequency offset in OFDM based systems. to appear in IEEE Transactions on Signal Processing, 2007.

    Google Scholar 

  15. Côme B, Hauspie D, Albasini G, et al.: Single-package direct-conversion receiver for 802.1 la wireless LAN enhanced with fast converging digital compensation techniques. Proceedings of IEEE MITT-S International Microwave Symposium Digest, June 2004, Fort Worth, Tex, USA 2: 555-558.

    Google Scholar 

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Correspondence to Deepaknath Tandur.

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Open Access This article is distributed under the terms of the Creative Commons Attribution 2.0 International License (https://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Tandur, D., Moonen, M. Joint Compensation of OFDM Frequency-Selective Transmitter and Receiver IQ Imbalance. J Wireless Com Network 2007, 068563 (2007). https://doi.org/10.1155/2007/68563

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  • DOI: https://doi.org/10.1155/2007/68563

Keywords

  • Cyclic Prefix
  • Channel Impulse Response
  • OFDM Symbol
  • Achievable Data
  • Achievable Data Rate