Improved carrier frequency offset correction for OFDM systems based on type-2 Control loop

Orthogonal frequency division multiplexing (OFDM) is much sensitive to carrier frequency offset (CFO). CFO distorts the orthogonality between subcarriers resulting in intercarrier interference (ICI). In this paper, an improved CFO estimation and correction scheme is proposed. The proposed scheme uses a dual bandwidth for acquisition and tracking process in phase locked loop (PLL) based on type-2 control loop for CFO tracking. The proposed dual bandwidth scheme leads to rapid acquisition and good tracking in the presence of noise for PLL using only one pilot tone from distributed pilots inside OFDM symbol. It is bandwidth efficient. It estimates and compensates the CFO up to 40% of the subcarrier spacing for 16-QAM modulation. The simulation is done for the additive white Gaussian noise (AWGN) and multipath Rayleigh-fading channel. The proposed dual bandwidth scheme reduces the acquisition time of PLL which makes the system faster and improves the bit error rate (BER).