Timing Drift Estimation and Compensation in 5G-NR Non-Terrestrial Networks

Non- Terrestrial Networks (NTN) were introduced as part of Release 17 in 5G by 3GPP to overcome the limitations of Terrestrial Networks. NTN was introduced to improve coverage over rural areas and high mobility scenarios like airplane, and to provide seamless global coverage. NTN uses Low/Medium/Geostationary orbit satellites to provide the required coverage. Among this, the Low Earth Orbit(LEO) has seen considerable deployment over the recent years due to relatively lower path-loss and propagation delays. But the challenges for LEO are high Doppler and fast variation in propagation delay, apart from the short duration of visibility for ground transceivers. In this paper we address the issue of varying propagation delay of LEO satellite from the perspective of a 5G receiver on ground using existing 5G-NR Physical Layer framework and potential solutions to overcome this. Simulation results are presented to show the gains obtained from compensating the timing drift for Downlink transmission.