Performance improvement in OFDM wireless LANS with a novel frequency synchronization

For WLAN applications frequency synchronization is one of the most important issues. The preamble allows the receiver to use efficient maximum likelihood algorithms to estimate and correct for the frequency offset, before the actual information portion of the packet starts. In order to increase the performance and provide frequency synchronization in orthogonal frequency-division multiplexing systems, we propose a new time domain approach for frequency synchronization algorithm. For this we first derive a data-aided maximum-likelihood estimator that operates on the received time domain signal. Several other type of synchronization algorithm has been proposed in different forms which are quite complex. In this method the training information required is at least two consecutive repeated symbols. As a note, the preamble of the WLAN standards satisfies this requirement for both the short and long training symbols. Computer simulation result show that the estimator performs well in a frequency selective slow Rayleigh fading channel as well as in an additive white Gaussian noise channel.