Robust integer frequency offset estimator with ambiguity of symbol timing offset for OFDM systems

In this paper, three different integer frequency offset estimators for orthogonal frequency-division multiplexing systems are derived: maximum-likelihood, blind, and correlation estimators. These are based on one pilot symbol with adjacent subcarriers differentially modulated. Specially, the correlation estimator attains a good performance even if there exists residual symbol timing offset. We present the method used to compose the pilot symbol and derive three estimators based on it. Results from simulations are presented to verify the performance of the estimators.