Methods for estimating a residual frequency error in a communications system

摘要

The present invention relates to methods and an apparatus for estimating a residual frequency error. According to an embodiment, an expected vector for selected subcarriers of a received symbol is estimated using a channel estimate vector and a reference vector; a sampling frequency mismatch is removed and a dot product is calculated using the expected and a received vector. An angle of the product is estimated and a change in angle from a previous symbol is calculated. The residual frequency is estimated using the calculated change in angle. In another embodiment, an expected subcarrier is estimated based on a channel estimate and on a reference subcarrier, an angle and magnitude of the multiplication between the expected and a received subcarrier are estimated; a phase offset is removed; a weighted mean value of the angles is calculated and the residual frequency error is estimated using a change in weighted mean angle.