Blind frequency-offset tracking scheme for multiband orthogonal frequency division multiplexing using time-domain spreading

A blind scheme for estimating the residual carrier-frequency offset of multiband orthogonal frequency division multiplexing (MB-OFDM)-based ultra-wideband (UWB) systems is proposed. In the MB-OFDM UWB system, time-domain spreading (TDS) is used by transmitting the same information across two adjacent OFDM symbols. By using the TDS structure, the proposed frequency estimation scheme does not require the use of pilot symbols. To demonstrate the usefulness of the proposed estimator, analytical expression of the mean square error is derived and the performance is compared with a conventional pilot-assisted estimator.