Patent ID: 7733971

Claim:
A method for recovering a carrier frequency of a received signal using a predefined symbol in an orthogonal frequency division multiplexing (OFDM) system, the method comprising the steps of: detecting at least three auto-correlation values and their corresponding offsets in descending order among auto-correlation values calculated within a specific frequency offset range between a received signal and a predefined symbol; comparing a ratio of a first auto-correlation value to a second auto-correlation value with a first threshold; determining whether first and second frequency offsets corresponding to the first and second auto-correlation values are adjacent to each other if the ratio of the first and second auto-correlation values is less than the first threshold; and determining an initial carrier frequency offset using a difference between the first frequency offset and a frequency offset correction value determined according to the system, if the first and second frequency offsets are adjacent to each other and a ratio of the second auto-correlation value and a third auto-correlation value is greater than a second threshold; wherein the first to third auto-correlation values represent the calculated auto-correlation values in descending order.