Under WiMAX OFDMA framework

two carrier-frequency offset （CFO） estimation methods for multiuser case were proposed for periodic ranging process. The theoretical results of the two methods were derived in the case of multiuser

in which the time-domain and frequency-domain correlation properties of PN code are used for extracting the desired ranging user respectively. Simulation results show that the proposed frequency-domain correlation method performs better than the time-domain correlation method even in the case of multiple users simultaneously existing in one ranging time-slot. And it more robust to timing offsets result from the symbol timing offset （STO） estimation error.