Abstract: A blind carrier frequency offset (CFO) tracking algorithm based on time-domain spreading (TDS) was proposed for multiband orthogonal frequency division multiplexing ultra wide band systems. The scheme uses data symbols and the mapped TDS ones to develop time and frequency-domain estimators and tracking loops respectively. Simulation results indicate that the proposed scheme has a better performance in tracking accuracy than pilots-aided ones. Under the SNR of 10dB, the mean square root errors of the residual CFO reach 2×10?4, and the bit error rate of the system is 10?6 of magnitude.