Abstract: OFDM syetems are very sensitive to frequency offset.Frequency shifts lead to loss of orthogonality between subcarriers,which will cause intercarrier interference and degrade the system performance.In view of the interference,the ICI caused by frequency offset is analyzed in theory.This paper compares the performances of three methods of ICI cancellation  based on symbol transform self-cancellation,extended Kalman filtering and frequency domain coding.The result shows that Frequency coding suppresses ICI effectively without reducing spectrum utilization.

Key words: OFDM, intercarrier interference, frequency offset