In this thesis, two signal-to-noise-ratio (SNR) estimators are analyzed for orthogonal frequency division multiplexing (OFDM) systems with imperfect synchronization. The two SNR estimators under investigation are the maximum likelihood estimator (MLE) and the second- and fourth-order moments estimator (MME). Mathematical analysis shows that the performance of MME is not affected by the advanced timing offset while a fixed bias of MLE is induced. Mathematical analysis also shows that the same frequency offset induces different bias for the two estimators under investigation. Finally, a novel carrier frequency offset and timing offset tracking scheme based on SNR estimation is proposed in this thesis.