Carrier frequency offset estimation in OFDM systems

This paper presents a basic useful technique for carrier frequency offset (CFO) estimation in orthogonal frequency division multiplexing (OFDM) over frequency selective fading channel. The performance of OFDM system is very sensitive to CFO, which introduces inter-carrier interference (ICI). In cyclic prefix (CP) based estimation, the CFO can be found from the phase angle of the product of CP and corresponding rear part of the OFDM symbol. In CFO estimation using training symbol, the CFO estimation range can be increased by reducing the distance between two blocks of samples for correlation. This was made possible by using training symbol that are repetitive with shorter period. An analytic expression in form of mean square error(MSE) of frequency offset synchronization is reported, and simulation results verify theoretical analysis.