Patent ID: 7684501

Claim:
An apparatus for carrier frequency offset compensation at a receiver of a communication system, wherein a symbol signal modulated by a carrier is transmitted via a plurality of subchannels, wherein the symbol signal comprises a pilot signal and the subchannels comprise at least a pilot subchannel for transmitting the pilot signal, the apparatus comprising: a pilot subchannel estimator for generating an estimated frequency response of the pilot signal; a frequency offset estimator, coupled to the pilot subchannel estimator, for generating an estimated carrier frequency offset according to a phase error between the estimated frequency response of the symbol signal in a frequency domain and an estimated frequency response of a following symbol signal in the frequency domain; a phase accumulator, coupled to the frequency offset estimator, for calculating an accumulated phase rotation according to the estimated carrier frequency offset; and a phase rotator, coupled to the phase accumulator, for carrier frequency offset compensation according to the accumulated phase rotation, wherein based on value of the estimated carrier frequency offset, the phase rotator performs frequency offset compensation in either the time domain or the frequency domain; wherein if the subchannels comprise a plurality of the pilot subchannels for transmitting a plurality of pilot signals, then the pilot subchannel estimator is for generating a plurality of estimated frequency responses corresponding to the pilot signals, and the frequency offset estimator coupled to the pilot subchannel estimator is for generating an estimated carrier frequency offset according to the estimated frequency responses of one of the pilot signals of the symbol signal and that of a corresponding pilot signal of a following symbol signal; and further wherein the estimated carrier frequency offset is generated through generating a plurality of phase errors, wherein each of the phase errors is generated according to the estimated frequency response of one of the pilot signals of the symbol signal and that of a corresponding pilot signal of the following symbol signal, and then averaging the phase errors.