Enhanced Carrier Frequency Offset Estimation Based on Zadoff-Chu Sequences

The carrier frequency offset (CFO) estimation through correlating a received Zadoff-Chu (ZC) sequence with a locally generated one is considered. The effect of the CFO on the correlation outputs is first analyzed. The obtained results justify for the first time the feasibility of estimating the CFO using an absolute value ratio (AVR)-based approach. Moreover, an existing AVR-based technique is re-visited and found to suffer from a sign flip problem, where the estimated CFO has a different sign from the true value, especially under small CFOs and/or low signal-to-noise ratios. An enhanced CFO estimator is thus proposed and shown to be able to effectively mitigate the sign flip issue and offer improved estimation accuracy over the original method.