Low-complexity estimation of CFO and frequency independent I/Q mismatch for OFDM systems

  • Authors:

  • Ying Chen;Jian Zhang;A. D. S. Jayalath

  • Affiliations:

  • Department of Information Engineering, The Australian National University, Canberra, Australia and Program of Networked Systems, National ICT Australia, Canberra, Australia;Department of Information Engineering, The Australian National University, Canberra, Australia and Program of Networked Systems, National ICT Australia, Canberra, Australia;School of Engineering Systems, Queensland University of Technology, Queensland, Australia

  • Venue:
  • EURASIP Journal on Wireless Communications and Networking
  • Year:
  • 2009

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Abstract

CFO and I/Q mismatch could cause significant performance degradation to OFDM systems. Their estimation and compensation are generally difficult as they are entangled in the received signal. In this paper, we propose some low-complexity estimation and compensation schemes in the receiver, which are robust to various CFO and I/Q mismatch values although the performance is slightly degraded for very small CFO. These schemes consist of three steps: forming a cosine estimator free of I/Q mismatch interference, estimating I/Q mismatch using the estimated cosine value, and forming a sine estimator using samples after I/Q mismatch compensation. These estimators are based on the perception that an estimate of cosine serves much better as the basis for I/Q mismatch estimation than the estimate of CFO derived from the cosine function. Simulation results show that the proposed schemes can improve system performance significantly, and they are robust to CFO and I/Q mismatch.