A Novel Maximum Likelihood Frequency Synchronizer for OFDM Systems

Feedback carrier frequency recovery for orthogonal frequency-division multiplexing (OFDM) signals transmitted over frequency selective fading channels is presented in this paper. Its derivation is based on minimum variance conditioned maximum likelihood (MV-CML) principle. The channel power on subcarriers required to perform frequency synchronization is regarded as unknown slowly time-variant parameter and is estimated online. The performance of the proposed synchronizer is assessed by computer simulations with comparison to that provided by other schemes and modified Cramer-Rao lower bound (MCRB). Both theoretical analysis and simulation results show that our synchronization scheme is a good candidate for OFDM frequency synchronization.