Time offset maintenance for nonterrestrial network (NTN)

A baseband (BB) processor for a base station operating in a non-terrestrial network (NTN), wherein the base station comprises a satellite or communicates with the satellite as a relay to a user equipment (UE), the BB processor configured to perform operations comprising:

• sending, to the UE, a timing offset indication signal comprising a time offset;
• and
• sending, to the UE, a timing drift rate indication signal comprising a timing drift rate for calculating an updated time offset, wherein the updated time offset comprises a timing advance (TA) value autonomously maintained at the UE;
• and
• receiving, from the UE, a timing offset update notification signal comprising the updated time offset.

A method for a user equipment (UE), comprising:

• receiving, from a base station in a non-terrestrial network (NTN), a timing offset indication signal comprising a time offset;
• receiving, from the base station in the NTN, a timing drift indication signal comprising a timing drift rate;
• determining an updated time offset based on the time offset and the timing drift rate, wherein the updated time offset comprises a timing advance (TA) value autonomously maintained at the UE;
• and
• transmitting, to the base station in the NTN, a timing offset update notification signal comprising the updated time offset.