New blind frequency offset estimator for OFDM systems over frequency selective fading channels

In this paper, a blind frequency offset estimator for orthogonal frequency division multiplexing (OFDM) systems over frequency selective fading channels based on modeling the unknown channel fading gains as deterministic variables is proposed. In this estimator, the received time domain OFDM samples are first partitioned into subsets, in which neighboring samples are uncorrelated, leading to a tri-diagonal signal correlation matrix for each subset. The ML cost functions from each of the subsets are combined to perform frequency offset estimation. Simulation results show that the proposed frequency offset estimator achieves better performance than the estimators reported in [J.-J. Van De Beek, M. Sandell, P.O. Borjesson, ML estimation of time and frequency offset in OFDM systems, IEEE Trans. Signal Process. 45 (July 1997) 1800–1805] and [X. Ma, G.B. Giannakis, S. Barbarossa, Non-data-aided frequency-offset and channel estimation in OFDM: and related block transmission, IEEE ICC’01, June 2001, pp. 1866–1870]. Moreover, although the power delay profile needs to be known in deriving the proposed estimator, simulation and analytical results show that the performance of the proposed estimator is not sensitive to variation in the power delay profile.