OFDM study – IQ-Imbalance Compensation in the Presence of IBI

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					      OFDM Equalization –
IQ-Imbalance Compensation in the
     Presence of IBI and CFO

                R94944007
                Kuo-Hsing Juan
OFDM

   OFDM (Orthogonal Frequency Division
    Multiplexing)
   Use N overlapped orthogonal sub-carriers to
    carry information
CFO

  CFO (Carrier Frequency Offset)
 Local oscillators are not synchronized well
 Introduce ICI
  (results in the
data disturbance)
IBI

   IBI (Inter Block Interference)
   Wireless channels are usually multi-path
    fading channels
   If the channel impulse response length is
    larger than the guard interval length in OFDM
    systems, this results in IBI.
IQ-Imbalance

   IQ-imbalance arises when the signal in I and
    Q channels do not meet the orthogonality
    and the power balance.
Motivation

   The analog front-end imperfections (IQ-
    Imbalance and CFO) and poor channel
    condition (IBI effect) cause a severe
    degradation in performance for OFDM
    systems.
   Study the equalization techniques that are
    robust against the imperfections.
Plan

   Model the channel condition and OFDM
    system
   Take CFO, IBI and IQ-Imbalance into
    consideration
   Study the equalization techniques
   Implement the equalization techniques
   Simulation
    Reference

   [1] Jui-Yuan Yu, Ming-Fu Sun, Terng-Yin Hsu, Chen-Yi Lee, "A
    novel technique for I/Q imbalance and CFO compensation in
    OFDM systems," 2005 IEEE International Symposium on Circuits
    and Systems, pp. 6030- 6033, vol. 6, 23-26 May 2005
   [2] I. Barhumi, M. Moonen, "IQ-Imbalance Compensation for
    OFDM in the Presence of IBI and Carrier-Frequency Offset," IEEE
    Transactions on Signal Processing, vol.55, no.1, pp.256-266, Jan.
    2007
   [3] J. Tubbax, A. Fort, L. Van der Perre, S. Donnay, M. Engels, M.
    Moonen, H. De Man, "Joint compensation of IQ imbalance and
    frequency offset in OFDM systems," 2003 Global
    Telecommunications Conference, vol.4, pp. 2365- 2369, 1-5 Dec.
    2003

				
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