Frequency synchronization for offset over the subcarrier spacing in OFDM systems

摘要

For a frequency offset estimation in orthogonal frequency division multiplexing (OFDM) systems, a method using correlation of the guard interval (GI) is proposed. However, this method estimates only the offset less than a half of the subcarrier spacing. This paper proposes frequency synchronization for the offset larger than the subcarrier spacing in OFDM systems under multipath fading channel. To estimate the offset larger than the subcarrier spacing, our proposed method uses an OFDM symbol which has some identical signals repeatedly within the OFDM symbol period. Frequency offset is estimated by performing correlation of this OFDM symbol. Moreover, the estimation performance is improved by using the principle of our previously proposed symbol timing estimation, which eliminates the effect of intersymbol interference (ISI). Simulation results show that the proposed method achieves good estimation performance and the degradation of system performance caused by frequency offset is sufficiently suppressed in the region of E{sub}b/N{sub}0 greater than 10 dB.