Performance study of residual carrier frequency offset estimation methods in OFDM WLAN systems

Residual carrier frequency offset accumulates with time and leads to bit errors on later symbols in an OFDM packet. This paper is concerned with two methods for residual carrier frequency offset estimation, based on the DFT demodulated data of OFDM data symbols at the pilot subcarriers. One method computes an estimate from the phase difference between the data in two (or more) consecutive symbols. The other one, which was recently proposed, finds an estimate from the phase of the data in one (or more) symbol. The latter method requires the a priori knowledge or an estimate of the channel while the former does not. The two methods have been compared by first-order perturbation analysis and simulation. A flaw of the latter method has been identified. Preference should be given to the former method in terms of estimation accuracy and ease of implementation in practical scenarios.