Patent ID: 7639750
Filing Date: 2009-12-29
Classification: H04L

Abstract:
1. A phase tracking device for an OFDM system, wherein the pilot sub-carriers and the data sub-carriers are bi-phase shift keying or quadrature phase shift keying, comprising: a sampler generating a first signal through sampling a received signal according to a sampling frequency adjusting signal; a phase compensator generating a second signal through adjusting a phase of the first signal according to a carrier frequency adjusting signal; a fast Fourier transform circuit generating a third signal through performing a fast Fourier transform on the second signal according to a symbol boundary index; an equalizer outputting an output signal through equalizing the third signal according to an estimated channel; a selector selecting the sub-carrier index of which is within a predetermined set or whose corresponding channel power is greater than a predetermined value out of the output signal; and a phase error metric processor generating a phase error metric according to a real part and an imaginary part of the selected output signal and a corresponding constellation type, and further generating the sampling frequency adjusting signal and the carrier frequency adjusting signal according to the estimated channel, selected sub-carrier index, and the-phase error metric, wherein the phase error metric approximates the phase difference between the selected output signal and an ideal signal multiplied by the corresponding channel power.