Sampling frequency offset estimation apparatus and method of OFDM system

A sampling frequency offset estimation method for an OFDM system, the method comprising:

• performing a first differential operation by performing complex conjugate multiplication of scattered pilots of complex symbols subjected to an FFT in an OFDM receiver;
• performing an interpolation by repeating, for a predetermined, first number of times, an operation of obtaining a median complex symbol between two consecutive complex symbols having first phase difference information obtained by the first differential operation;
• performing a second differential operation by performing complex conjugate multiplication of two consecutive median complex symbols among the median complex symbols obtained by performing the interpolation;
• and
• performing a sampling frequency offset estimation by estimating sampling frequency offset using complex symbols having second phase difference information obtained by performing the second differential operation, wherein
• the performing a sampling frequency offset estimation comprises taking arctangents of the complex symbols having the second phase difference information obtained by the second differential operation, obtaining a sum of the arctangents, and multiplying the sum by
• 1
• 2
• ⁢
• π
• ⁢
• ⁢
• Nt
• to estimate the sampling frequency offset, where Nt=bspNs(Nsp−Na−1) is satisfied, bsp is spacing between scattered pilots (b is spacing between pilots), Ns is the length of an OFDM symbol (N is the length of FFT), Nsp is the number of scattered pilots, and Na is the number of interpolations being performed.