Abstract: It summarized the principles and steps of existing typical carrier frequency offset (CFO) estimation algorithms over timevarying frequencyselective channels in the OFDM system, compared these algorithms through simulation of the CFO estimation performance, and analyzed their advantages and disadvantages. The research provides a useful reference for further studies of frequency synchronization in future.

Key words: orthogonal frequency division multiplexing(OFDM); timevarying channel; corrier frequency offset(CFO) estimation; pilot ; Kalman filtering