Patent ID: 6618352
Filing Date: 2003-09-09
Classification: H04L

Abstract:
An OFDM demodulator for receiving an OFDM signal generated from a plurality of subcarriers modulated with transmitted data for each given-length symbol, said OFDM demodulator comprising:Fourier transform means for separating the OFDM signal into the plurality of subcarriers by Fourier transform to generate a first subcarrier signal; carrier phase error detecting means for obtaining an amount of phase correction for each of the plurality of subcarriers in the first subcarrier signal based on subcarriers of known phase assigned as pilot carriers to provide phase reference in the first subcarrier signal; and phase correcting means for correcting a phase of the first subcarrier signal based on the amounts of phase correction to generate a second subcarrier signal, wherein said carrier phase error detecting means comprises: pilot carrier location detecting means for detecting locations of the pilot carriers in the first subcarrier signal to generate a pilot carrier locationâ€² signal; pilot carrier extracting means for extracting a first pilot carrier from the first subcarrier signal based on the pilot carrier location signal; a pilot carrier memory operable to hold known pilot carriers and read a second pilot carrier corresponding to the detected location among the known pilot carriers based on the pilot carrier location signal; phase difference calculating means for calculating a phase difference between the first and second pilot carriers to generate a phase difference signal indicating the phase difference; phase change amount calculating means for calculating an amount of change of phase rotation between transmitting and receiving ends with respect to a carrier frequency based on the phase difference signal and generating a phase difference change signal indicating the amount of change; and phase correction amount calculating means for calculating an amount of phase correction for each of the plurality of subcarriers based on the phase difference signal and the phase difference change signal and generating a phase error correcting signal.