OFDM Equalization –
IQ-Imbalance Compensation in the
Presence of IBI and CFO
OFDM (Orthogonal Frequency Division
Use N overlapped orthogonal sub-carriers to
CFO (Carrier Frequency Offset)
Local oscillators are not synchronized well
(results in the
IBI (Inter Block Interference)
Wireless channels are usually multi-path
If the channel impulse response length is
larger than the guard interval length in OFDM
systems, this results in IBI.
IQ-imbalance arises when the signal in I and
Q channels do not meet the orthogonality
and the power balance.
The analog front-end imperfections (IQ-
Imbalance and CFO) and poor channel
condition (IBI effect) cause a severe
degradation in performance for OFDM
Study the equalization techniques that are
robust against the imperfections.
Model the channel condition and OFDM
Take CFO, IBI and IQ-Imbalance into
Study the equalization techniques
Implement the equalization techniques
 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
 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.
 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.