Cross-relation-based frequency-domain blind channel estimation with multiple antennas in orthogonal frequency division multiplexing systems

Frequency domain blind channel estimation methods for orthogonal frequency division multiplexing (OFDM) systems with multiple antennas are proposed, in which the cross relation between the channel gains and a single snapshot of the received signal on each subcarrier is utilised. Necessary and sufficient conditions for the identifiability of a single-input multiple-output OFDM channel estimator are derived and, furthermore, using a first-order perturbation analysis, the approximation of mean-squared-error (MSE) is analytically obtained, which shows that the proposed estimator is approximately unbiased at high signal-to-noise ratio. The proposed estimator exhibits lower MSEs than those of both the existing subspace-based and deterministic blind channel estimators and is less sensitive to the estimation error of the number of multipaths. Finally, the extension of the proposed channel estimation to multiple-input–multiple-output OFDM is presented.