Frequency Offset Compensation for Satellite Communication System with CE-OFDM

Constant envelope orthogonal frequency division multiplexing (CE-OFDM) is a waveform that can achieve 0dB peak-to-average power ratio and avoid the signal distortion caused by the nonlinear power amplifier. However, the carrier frequency offset (CFO) in CE-OFDM systems can cause errors at phase unwrapper module. In this paper, a CFO estimation scheme is proposed for CE-OFDM in satellite communication system. As the null subcarrier is inherent in the conjugate symmetric symbol structure at the transmitter, the proposed scheme uses the null subcarrier as prior information to estimate the CFO at the receiver. The ideal estimation range of normalized CFO is obtained by mathematical analysis. Simulation results show that the proposed scheme can estimate the CFO accurately under additive white Gaussian noise (AWGN) channel and multipath fading channel, especially for moderate and high signal-to-noise ratio (SNR).