How is the timing and synchronization handled in non-terrestrial networks?
Timing and synchronization are manually adjusted by the network operator based on the distance between the Earth and the satellites.
The network broadcasts ephemeris information and common Timing Advance (common TA) parameters in each non-terrestrial network cell to ensure uplink synchronization.
The UE continuously updates the Timing Advance and frequency pre-compensation in connected mode to account for the long propagation delays in non-terrestrial networks.
The UE acquires its GNSS position as well as the satellite ephemeris and common TA before connecting to a non-terrestrial network cell.
Timing and synchronization are enhanced by a Common Timing Advance (Common TA) and two scheduling offsets: Δt_RP-RP, which corresponds to the Round Trip Time (RTT), and Δt_UL-SL, which corresponds to the sum of the service link RTT and the common TA.