A near blind low complexity carrier frequency offset estimator for OFDM

A semi blind technique for estimating the carrier frequency offset in OFDM communication systems is presented in this paper. The fractional and integer frequency offsets are estimated by employing a few null subcarriers in the first OFDM symbol in a frame. While the conventional null subcarrier based methods estimate the offset by a single global search, the proposed method employs a two stage estimator, which greatly minimize the computational complexity. We also present a novel null subcarrier allocation scheme which ensures an estimation range equal to the OFDM bandwidth. Furthermore, the bandwidth overhead of the proposed scheme is very low compared to many earlier approaches which use only null subcarriers or periodic training sequences. The MSE and BER performance of the proposed method is compared with that of a recently published method.