Carrier frequency offset estimation for OFDM systems

Orthogonal frequency division multiplexing (OFDM) is broadly considered as an effective approach for future high-speed wireless multimedia communications. However, it is very sensitive to carrier frequency offset between the transmitter and the receiver local oscillators, which causes intercarrier interference (ICI). Thus, in OFDM communication systems, the carrier frequency offset must be estimated and compensated at the receiver to minimize the effects of ICI and maintain orthogonality. We first derive a mathematic model of OFDM systems with cyclic prefix (CP) and virtual subcarrier. For the ESPRIT-like estimator, we propose a carrier frequency offset estimation algorithm using a DOA-MATRIX method. After the rough estimation, it can simultaneously acquire the frequency offset and matrix, including channel information, which are favorable for offset compensation and demodulation of the received signals. Numerical simulations illustrate the performance of the algorithm.