Spec 38.331 section 5.2.2.4.21 indicates this
1> start or restart T430 for serving cell with the timer value set to ntn-UlSyncValidityDuration for the serving cell
from the subframe indicated by epochTime for the serving cell;
NOTE: UE should attempt to re-acquire SIB19 before the end of the duration indicated by ntn-UlSyncValidityDuration and epochTime
Epochtime IE
When explicitly provided through SIB, or through dedicated signaling, the EpochTime is the starting time of a DL
sub-frame, indicated by a SFN and a sub-frame number signaled together with the assistance information.
For serving cell, the field sfn indicates the current SFN or the next upcoming SFN after the frame where the message indicating the epochTime is received.
This field is mandatory present when ntn-Config is provided in dedicated configuration.
gNB implementation related to epochtime will be done in a separate merge request.
Raghavendra Dinavahi
6fc02164c5