Time offset maintenance for nonterrestrial network (NTN)
A user equipment (UE) associated with a non-terrestrial network (NTN) is disclosed. The UE comprises a processor configured to determine a first time offset, based on processing a timing offset indication signal comprising the first time offset or an associated parameter, received from a base station. In some embodiments, the first time offset is indicative of a time delay in downlink (DL) to uplink (UL) interaction between the UE and the base station. The processor is further configured to determine a second time offset, based on processing a subsequent timing offset indication signal comprising the second time offset or an associated parameter, received from the base station at a subsequent time instance. In some embodiments, the processor is further configured to update the first time offset with the second time offset.
1 . A baseband (BB) processor for a user equipment (UE), the BB processor configured to perform operations 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 rate 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
providing, to the base station in the NTN, a timing offset update notification signal comprising the updated time offset.
2 . The BB processor of claim 1 , wherein determining to update the time offset with the updated time offset is triggered in response to the TA value autonomously maintained at the UE exceeding a predefined TA threshold.
3 . The BB processor of claim 1 , wherein the updated time offset is indicative of a time delay between a downlink (DL) transmission and an uplink (UL) transmission for communication between the UE and the base station, and wherein the updated time offset is greater than or equal to two times a propagation delay between the UE and the base station.
4 . The BB processor of claim 1 , wherein the time offset is indicated as a number of slots.
5 . The BB processor of claim 1 , wherein the timing drift rate comprises a common drift rate.
6 . The BB processor of claim 1 , wherein determining the updated time offset is further based on a time gap between a reception of the timing drift rate indication signal and a previously received timing drift rate indication signal.
7 . 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.
8 . The BB processor of claim 7 , wherein the updated time offset is indicative of a time delay between a downlink (DL) transmission and an uplink (UL) transmission for communication between the UE and the base station, and wherein the updated time offset is greater than or equal to two times a propagation delay between the UE and the base station.
9 . The BB processor of claim 7 , wherein the time offset is indicated as a number of slots.
10 . The BB processor of claim 7 , wherein the operations further comprise receiving the timing offset update notification signal when the updated time offset exceeds a TA threshold at the UE.
11 . The BB processor of claim 7 , wherein the timing drift rate comprises a common drift rate.
12 . 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.
13 . The method of claim 12 , wherein the timing drift rate comprises a common drift rate.
14 . The method of claim 12 , wherein determining the updated time offset is further based on a time gap between a reception of the timing drift rate indication signal and a previously received timing drift rate indication signal.
15 . The method of claim 12 , further comprising transmitting the timing offset update notification signal when the updated time offset exceeds a TA threshold at the UE.