In this study, for interleaved orthogonal frequency division multiple access uplink with multi-antenna receiver, we propose two generalised carrier frequency offset estimators which, respectively, exploit the subspace theory and maximumlikelihood (ML) criterion. We find that, as long as the numbers of multipaths from two of the users are smaller than the number of antennas at the receiver, both the proposed estimators support fully loaded transmissions. We also derive the theoretical performance lower bound for the proposed ML estimator. The numerical results are then provided, which corroborate the proposed studies.