Frequency offset estimation for OFDM by using a correlation sequence

Based on the Hadamard product of known frequency domain preamble sequence and its conjugate shift sequence, a new sequence with much better auto-correlation property was constructed. Combined with the arithmetic of cross-correlation, an improved integer frequency offset (IFO) estimation algorithm was proposed. Through Monte-Carlo simulations, the distribution of the expectations and variances of the metric function of newly developed algorithm was analyzed over AWGN channels. The proposed algorithm has been applied in IEEE 802.16d system and simulations were carried out. Simulation results show that the newly proposed method can overcome the serious disturbance introduced by large timing offset. When the SNR is greater than 10 dB, the detection probability of IFO can be accurately obtained without increasing the complexity of calculation.