Feedback frequency synchronization for OFDM applications

Maximum likelihood estimation techniques are often used to derive carrier frequency recovery schemes for digital receivers. Unfortunately, their rigorous application is generally hindered by analytical difficulties and, in consequence, some approximations must be made to achieve practical results. We concentrate on frequency recovery for orthogonal frequency division multiplexing signals, a problem already discussed in the literature. Following Daffara and Chouly (1993) we derive a feedback synchronizer based on maximum likelihood estimation methods. Making different approximations, however, we come up with a scheme that is superior in two respects: it has better accuracy and is simpler to implement. Comparisons are made with other feedback schemes based on heuristic reasoning.