Carrier frequency offset estimation using fractional fourier transform and CAZAC sequences

The major drawback of Orthogonal Frequency division Multiplexing (OFDM) is sensitivity to carrier frequency offset which it is due to difference between carrier frequencies in the transmitter and receiver (due to difference between oscillators in the transmitter in the receiver) and the movement of mobile station. This carrier frequency offset generates inter-carrier interference (ICI) and inter-symbol interference (ISI). That is why, it is necessary to estimate this offset in order to compensate it in the receiver side. Lot of paper discus this objection to estimate carrier frequency offset (CFO) using usual Fourier Transform. This paper deals with a novel method using Fractional Fourier Transform in conjunction with Constant Amplitude Zero Auto-Correlation (CAZAC) sequences as training sequences. Computer simulation in CFO estimation shows that FRFT give an advantage in term of MSE in comparison with classical FT (Fourier transform) and especially with the use of CAZAC sequences.