Frequency ambiguity resolution in OFDM systems

In orthogonal frequency division multiplexing systems, the carrier-frequenc y offset can be divided into two parts: 1) an integer one-multiple of the s ubcarrier spacing 1/T and 2) a fractional one-less than 1/2T in amplitude. Some schemes proposed in the literature can only recover the fractional par t. In this letter we derive two algorithms for estimating the integer part. They are based on the observation of two consecutive OFDM symbols. The fir st algorithm exploits pilot symbols multiplexed with the data, the other is blind.