Patent ID: 8270509

Claim:
A method of determining, in a receiver of a wireless communications system employing Orthogonal Frequency Division Multiplexing, a frequency error (f err ) of received signals compared to corresponding signals generated in the receiver; wherein the received signals comprise symbols, each symbol of a given duration being transmitted as a number of cells on a corresponding number of subcarrier frequencies; and wherein some of said cells are pilot cells modulated with reference information whose transmitted value is known to the receiver; the method comprising the steps of: the receiver determining a change from one symbol to another of a phase difference between said received and generated signals, wherein the receiver determining the change further comprises the steps of: the receiver selecting at least three pilot cells from at least two different symbols, each of said at least three pilot cells being selected from a different sub-carrier frequency; the receiver determining a position for each of said at least three pilot cells, the position of a pilot cell being defined as the symbol and the sub-carrier frequency on which the pilot cell is transmitted; the receiver determining for each of said at least three pilot cells a phase difference between said received and generated signals; the receiver determining from said determined phase differences, for each of at least two selected pairs of said at least three pilot cells a change of phase difference between the two pilot cells of the pair; the receiver calculating a change in phase difference caused by said frequency error as a weighted sum of said determined phase changes using the positions of each of said at least three pilot cells; and the receiver calculating the frequency error from said calculated change in phase difference.