Abstract: A method for estimating carrier frequency offset (CFO) and sampling frequency offset (SFO) in an Orthogonal Frequency Division Multiplexing (OFDM) system having a plurality of pilot tones. The absolute phase angle for each pilot tone is measured, and estimates of the CFO and the SFO are derived using a weighted least-squares methodology. More particularly, the phase of each pilot tone is measured for a number (n) of symbol times; for each of the pilot tones, the slope of a phase angle change from symbol time to symbol time is estimated using a best least-squares fit of the measured phases to a straight line; and a weighted least-squares best-fit straight line is determined to find an estimated phase angle differential value (?(i)) for each pilot tone; wherein a slope of the best-fit straight line yields an estimate of the SFO, and an intercept with the best-fit straight line yields an estimate of the CFO.

Abstract: A method and apparatus for accurately estimating the carrier frequency offset and the carrier phase offset of a digitally modulated signal using a signal processing algorithm to initialize the state variables of a Phase-Locked Loop (PLL) is disclosed. A sequence of phase values is estimated from a received sequence of symbols and the angular effect due to the modulation format is removed from the sequence of phase values. A curve-fit algorithm based in one embodiment on the RLS algorithm is then applied to a sequence of unwrapped phase values to estimate the carrier frequency offset and the carrier phase offset.

Abstract: A method for estimating carrier frequency offset (CFO) and sampling frequency offset (SFO) in an Orthogonal Frequency Division Multiplexing (OFDM) system having a plurality of pilot tones. The absolute phase angle for each pilot tone is measured, and estimates of the CFO and the SFO are derived using a weighted least-squares methodology. More particularly, the phase of each pilot tone is measured for a number (n) of symbol times; for each of the pilot tones, the slope of a phase angle change from symbol time to symbol time is estimated using a best least-squares fit of the measured phases to a straight line; and a weighted least-squares best-fit straight line is determined to find an estimated phase angle differential value (&agr;(i)) for each pilot tone; wherein a slope of the best-fit straight line yields an estimate of the SFO, and an intercept with the best-fit straight line yields an estimate of the CFO.

Abstract: A method and apparatus for accurately estimating the carrier frequency offset and the carrier phase offset of a digitally modulated signal using a signal processing algorithm to initialize the state variables of a Phase-Locked Loop (PLL) is disclosed. A sequence of phase values is estimated from a received sequence of symbols and the angular effect due to the modulation format is removed from the sequence of phase values. A curve-fit algorithm based in one embodiment on the RLS algorithm is then applied to a sequence of unwrapped phase values to estimate the carrier frequency offset and the carrier phase offset.