A New Approach to Frequency Acquisition in OFDM Systems with Periodic Preambles

In this paper, a novel carrier frequency offset estimation algorithm is derived. An OFDM system is considered where some periodic training symbols are sent as preamble. The proposed approach reduces the carrier acquisition problem to the frequency estimation of a set of complex tones with the same frequency. Then, a maximum likelihood estimation algorithm is derived, which offers very good performance in low SNR multipath scenarios. The major part of the computations needed in the proposed algorithm can be efficiently carried out in the FFT processor already available in any OFDM receiver. Simple enhancing methods are analyzed to overcome the limits of the available FFT processor and achieve full performance.