Cross ambiguity function based integer frequency offset estimation for OFDM systems

Using only one training symbol, a novel cross ambiguity function (CAF) based integer frequency offset (IFO) estimator for OFDM systems is proposed. From the energy distribution characteristics of the ideal CAF, an energy-detection based metric is obtained. By designing a training symbol whose ambiguity function (AF) is a valid approximation of the ideal thumbtack-type AF, a high-accuracy and full-range IFO estimation can be achieved over frequency-selective fading channels. Furthermore, the adoption of the CAF expression in terms of time-domain signals keeps the complexity of the proposed algorithm at a relatively low level. Simulation results verify its superior accuracy of the IFO estimation over conventional algorithms.