Doppler Frequency Offset Estimation in OFDM systems

This paper presents frequency offset estimation algorithm in wireless OFDM cellular system such as 3G-LTE. We first analyze the method of frequency offset estimation in general OFDM system. The analysis will show that the value of frequency offset estimation in cell boundary is inaccurate. Because Doppler frequencies of signals transmitted from different base stations are different, the error of frequency offset estimation value is generated. We show how proposed algorithm can reduce the error of frequency offset estimation. Results of simulation show that the utilization of proposed algorithm can reduce the error of frequency offset estimation considerably. Proposed frequency offset estimation algorithm can increase overall system capacity because of performance improvement in cell boundary. Especially, 16-QAM or 64-QAM modulations for high data rate transmission is extremely sensitive to frequency offset, therefore proposed algorithm increases channel capacity for user in cell boundary.