Abstract:OFDM systems is sensitive to the frequency offset. In this paper, a novel frequency ambiguity resolution algorithm in OFDM systems based on null subcarrier detection is proposed to correct the frequency ambiguity. It utilizes the subcarriers which transmit no information bit to correct the frequency ambiguity. In the paper, the effect of timing error on the performance of proposed algorithm is analyzed and the computational complexity of the proposed algorithm is compared with that of conventional algorithm. Simulation results show that the proposed algorithm has the low complexity advantage over conventional algorithm while maintain the same performance.