Abstract: According to the requirements of the adaptive control in wireless OFDM systems and the weakness of Boumard’s method, a novel SNR estimation algorithm based on the preamble is proposed for OFDM systems. The average powers of signal and noise are estimated by making full use of the frequency autocorrelation characteristics of the received preamble data and the wireless channels, and thus the average SNR of the system is obtained. By using the estimated coefficients of the sub-channels, the SNR of each subchannel can also be obtained. Simulation results show that the performance of the proposed algorithm is better than that of Boumard’s method, and obtains an improvement by more than 10 times at the low SNR.

Key words: OFDM, SNR estimation, autocorrelation function