Patent ID: 7515902

Claim:
A velocity estimation apparatus in a communication system, in Rician fading environments in which a direct wave exists, including a transmitter for transmitting signals through radio channels and a receiver for receiving the signals and restoring data, the apparatus comprising: a pilot separation unit for separating a pilot signal from the received signal; a maximum Doppler frequency estimator for estimating a maximum Doppler frequency by means of the pilot signal output from the pilot separation unit; and a velocity information generator for converting an estimated value of the maximum Doppler frequency estimated by the maximum Doppler frequency estimator into velocity information, wherein the maximum Doppler frequency estimator comprises: an auto-covariance calculation unit for outputting auto-covariance values by means of the pilot signal; and a maximum Doppler frequency calculation unit for obtaining the maximum Doppler frequency by means of the auto-covariance values output from the auto-covariance calculation unit, wherein the auto-covariance calculation unit comprises: a first auto-covariance module for performing an auto-covariance operation having a predetermined time difference for the pilot signal, thereby outputting a first auto-covariance value; a second auto-covariance module for performing an auto-covariance operation without the time difference for the pilot signal, thereby outputting a second auto-covariance value; a third auto-covariance module for performing an auto-covariance operation without the time difference for a square value of the pilot signal, thereby outputting a third auto-covariance value; and a fourth auto-covariance module for performing an auto-covariance operation having the predetermined time difference for the square value of the pilot signal, thereby outputting a fourth auto-covariance value.