Synchronization for OFDM-Based Satellite Communication System

The integration of satellite and the terrestrial cellular network is a promising technology to provide global ubiquitous communication. As orthogonal frequency-division multiplexing (OFDM) has been adopted in the 3GPP standards, such as 4G LTE and the ongoing 5G new radio (NR), it will become an important feature of the satellite to achieve a high degree of commonality with the terrestrial cellular networks, i.e. LTE or 5G. For OFDM systems, synchronization is crucial for the initial attach processing. Unlike the traditional OFDM-based terrestrial cellular systems, synchronization in OFDM-based satellite is facing new challenges, due to the higher Doppler shift in the satellite system. In this paper, we analyze the impact of large doppler on the synchronization of the OFDM-based satellite system and then propose new methods to estimate the carrier frequency offset for the OFDM-based satellite. The advantages of the proposed methods are as follows: first, the proposed methods are compatible with the procedures of the LTE and NR; second, our methods are designed based on the features of the satellite channel, it is suitable for the OFDM-based satellite system; third, the complexity of our methods, whose primary computational efforts are relatively cheap matrix-vector multiplications, is lower than the previous methods.