A New Carrier Frequency Loop for OFDM Systems

We derive a decision-directed carrier frequency estimator for OFDM systems. The estimator has a closed loop structure and is based on maximum likelihood inspired methods. A simplified version of the loop is also developed that can be implemented with relatively low complexity and acceptable degradations compared with the optimum scheme. The estimation accuracy is assessed by computer simulation for AWGN and frequency-selective multipath channels. Comparisons are made with other schemes discussed in the literature. Simulation results indicate that the proposed loop has better performance.