A Hybrid Integer Carrier Frequency Offset Estimator for Practical OFDM Systems

In orthogonal frequency-division multiplexing (OFDM) systems, the integer part of carrier frequency offset (CFO) as a multiple of subcarrier spacing needs to be estimated from the frequency-domain signal. The performance of the autocorrelation based method is quite poor, while the channel knowledge based method is too complex for hardware real-time implementation. To provide improved tradeoffs between the performance and complexity, we propose a new hybrid algorithm that filters away unlikely integer CFO candidates with the autocorrelation method and determines the most likely estimate with channel knowledge. The analytical performance of the proposed hybrid method agrees with the simulation results and both demonstrate the cost-effectiveness of the method even in challenging wireless channel conditions.