Method and apparatus for evaluating service time for an NTN cell in a wireless communication system

1 . A method, comprising,

receiving, by a wireless device from a network, information related to non-terrestrial network access,

wherein the information related to non-terrestrial network access includes (1) information related to a location of a reference point for a non-terrestrial network NTN cell by time, (2) information related to a trace of a reference point for the non-terrestrial network cell, and (3) information related to one or more secant values per vertical distance range;

calculating, by the wireless device, a remaining service trace based on (4) a secant value, among the one or more secant values, corresponding to a vertical distance between the wireless device and the trace of the reference point and (5) a horizontal distance between the wireless device and the reference point;

evaluating, by the wireless device, remaining service time for the non-terrestrial network cell based on the remaining service trace and a velocity of the reference point; and

determining, by the wireless device, whether to perform a mobility to the non-terrestrial network cell based on the remaining service time.

2 . The method of claim 1 , wherein the cell coverage information includes information on a distance threshold.

3 . The method of claim 2 , wherein the method further comprises,

determining, by the wireless device, whether a distance between the wireless device and the reference point is lower than or equal to the distance threshold.

4 . The method of claim 3 , wherein the step of calculating the remaining service trace and the step of evaluating the remaining service time are initiated based on determining that the distance between the wireless device and the reference point is lower than or equal to the distance threshold.

5 . The method of claim 1 , wherein the cell coverage information includes information on the velocity of the reference point.

6 . The method of claim 1 , wherein the horizontal distance between the wireless device and the reference point is calculated from a distance between the wireless device and the reference point and the vertical distance between the wireless device and the trace of the reference point.

7 . The method of claim 1 , wherein the mobility to the non-terrestrial network cell includes a cell reselection to the non-terrestrial network cell.

8 . The method of claim 7 , wherein the method further comprises,

comparing, by the wireless device, the remaining service time of the non-terrestrial network cell with other non-terrestrial network cells; and

performing, by the wireless device, the cell reselection based on that the remaining service time of the NTN cell is the longest.

9 . The method of claim 1 , wherein the method further comprises,

performing, by the wireless device, measurement on the non-terrestrial network cell based on the remaining service time.

10 . The method of claim 1 , wherein the remaining service trace is calculated by adding the horizontal distance to half of the secant value corresponding to the vertical distance, based on that the reference point is getting closer to the wireless device.

11 . The method of claim 1 , wherein the remaining service trace is calculated by subtracting the horizontal distance from half of the secant value corresponding to the vertical distance, based on that the reference point is getting further from the wireless device.

12 . The method of claim 1 , wherein the remaining service time is calculated by dividing the remaining service trace by the velocity of the reference point.

13 . The method of claim 1 , wherein the wireless device is in communication with at least one of a user equipment, a network, or an autonomous vehicle other than the wireless device.

14 . A wireless device in a wireless communication system comprising:

a transceiver;

a memory; and

at least one processor operatively coupled to the transceiver and the memory, and configured to perform operations, the operations comprising:

receiving, from a network, information related to non-terrestrial network access,

wherein the information related to non-terrestrial network access includes (1) information related to a location of a reference point for a non-terrestrial network cell by time, (2) information related to a trace of a reference point for the non-terrestrial network cell, and (3) information related to one or more secant values per vertical distance range;

calculating a remaining service trace based on (4) a secant value, among the one or more secant values, corresponding to a vertical distance between the wireless device and the trace of the reference point and (5) a horizontal distance between the wireless device and the reference point;

evaluating remaining service time for the non-terrestrial network cell based on the remaining service trace and a velocity of the reference point; and

determining whether to perform a mobility to the non-terrestrial network cell based on the remaining service time.

15 . The wireless device of claim 14 , wherein the cell coverage information includes information on a distance threshold.

16 . The wireless device of claim 15 , wherein the at least one processor is further configured to,

determine whether a distance between the wireless device and the reference point is lower than or equal to the distance threshold.

17 . The wireless device of claim 16 , wherein the step of calculating the remaining service trace and the step of evaluating the remaining service time are initiated based on determining that the distance between the wireless device and the reference point is lower than or equal to the distance threshold.

18 . The wireless device of claim 14 , wherein the cell coverage information includes information on the velocity of the reference point.

19 . The wireless device of claim 14 , wherein the horizontal distance between the wireless device and the reference point is calculated from a distance between the wireless device and the reference point and the vertical distance between the wireless device and the trace of the reference point.

20 . A base station in a wireless communication system comprising:

a transceiver;

a memory; and

a processor operatively coupled to the transceiver and the memory, and configured to:

control the transceiver to transmit, to a wireless device, cell coverage information for a Non-Terrestrial Networks (NTN) cell including (1) information on a location of a reference point for the NTN cell by time, (2) information on a trace of a reference point for the NTN cell, and (3) information on one or more secant values per vertical distance range.