Apparatus for estimating frequency offset in OFDM system

An apparatus for estimating a frequency offset using one training symbol including first and second training symbols, which include an integer number N samples and have the same structure and value, in an OFDM system, comprising:

• a first likelihood function calculator for calculating non-Gaussian impulsive noise included in the training symbol by a likelihood function of a Cauchy distribution in which a characteristic exponent of a bivariate isotropic symmetric alpha-stable (BISαS) probability density function is 1;
• a second likelihood function calculator for calculating non-Gaussian impulsive noise included in the training symbol by a likelihood function of a Gaussian distribution in which the characteristic exponent of a BISαS probability density function is 2;
• a second frequency offset estimator for estimating a first frequency offset estimation value by adding correlation values of two samples separated by N/2 for k from 0 to
• N
• 2
• -
• 1
• in the likelihood function of the Gaussian distribution of the second likelihood function calculator;
• a trial value set calculator for calculating the correlation values of the second frequency offset estimator as N/2 effective frequency offset values according to values of the N samples;
• and
• a third frequency offset estimator for estimating an effective frequency offset value in which the likelihood function of the Gaussian distribution of the first likelihood function calculator is highest among the effective frequency offset values of the trial value set calculator as a second frequency offset estimation value.