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