Residual Frequency Offset and Phase Compensation for OFDM Systems

In orthogonal frequency division multiplexing (OFDM) systems, carrier frequency offset (CFO) due to mismatch of the local oscillators causes inter-carrier interference (ICI), which may result in significant performance degradation. Although, several frequency synchronization schemes were reported, there possibly remains frequency offset and it can still generate ICI and induces phase distortion of the OFDM symbols. In this paper, we propose a method to compensate both residual frequency offset (RFO) and RFO induced phase error (PE) by the Kalman filter. Our approach is based on building a simple robust state-space model and the Kalman filter is then applied to estimate and track the RFO and PE. Simulation results show that the proposed method significantly compensates the performance degradation due to RFO and almost achieves ideal packet error rate (PER) performance with lower complexity.