Patent ID: 8781029

Claim:
A frequency offset estimation apparatus which estimates a frequency offset which is the difference between a carrier frequency of a received signal and the frequency of an output signal of a local oscillator, the apparatus comprising: a frequency domain conversion unit that converts the received signal sampled in advance with a predetermined sampling frequency into a frequency domain, and outputs a frequency spectrum having N frequency components to which numbers from 1 to N (N is an arbitrary natural number) have been sequentially assigned in order of the size of a frequency; a frequency band limitation unit that limits a frequency band of negative frequency components which have frequency component numbers of 1 to N/2 of the frequency spectrum and a frequency band of positive frequency components which have frequency component numbers of N/2+1 to N of the frequency spectrum; and a frequency offset estimation control unit that calculates the sum of the squares of the positive frequency components of the frequency spectrum that have been subjected to frequency band limitation and the sum of the squares of the negative frequency components of the frequency spectrum that have been subjected to frequency band limitation to calculate power of the positive frequency components and power of the negative frequency components, and cyclically shifts all frequency components of the frequency spectrum in a frequency domain until the absolute value of a power difference calculated from the power of the positive frequency components and the power of the negative frequency components is less than or equal to a predetermined threshold value, and estimates the frequency offset based on a shift amount until the absolute value is less than or equal to the threshold value.