1. OFDM Equalization – IQ-Imbalance Compensation in the Presence of IBI and CFO
Kuo-Hsing Juan

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

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

4. 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.

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

6. 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.

7. 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

8. 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 , vol. 6, 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 , 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 , 1-5 Dec. 2003