Maximum likelihood estimation of OFDM carrier frequency offset

Blind estimation of the OFDM carrier frequency offset (CFO) is studied in this paper. Maximum likelihood estimation is developed in the presence of virtual carriers. It turned out that the resulting estimator has an identical form to that of a previously proposed blind estimation scheme by Liu and Tureli (see IEEE Communications Letters, vol.2, p.104-6, April 1998). We explain, using the projection argument, why these two estimators are equivalent. For improved CFO estimation performance, multiple OFDM blocks can be utilized. Alternatively receiver diversity may be used in the CFO estimation. We show that in both cases, the estimator again reduces to the form similar to that of the MUSIC-like algorithm.. Performance improvement is shown using both the Cramer Rao lower bound and numerical examples