1 . A method for selecting a non-terrestrial network (NTN) cell by a user equipment (UE), the method comprising: receiving one or more system parameters from a serving NTN cell and a plurality of NTN neighbor cells; determining trajectory information associated with the plurality of NTN neighbor cells based on the one or more received system parameters; and selecting, based on the determined trajectory information associated with the plurality of NTN neighbor cells, the NTN cell among the plurality of NTN neighbor cells to perform at least one of a cell reselection or a conditional hand over (CHO).
2 . The method of claim 1 , further comprising: determining a service time duration for each of the plurality of NTN neighbor cells based on the received one or more system parameters; and determining a trajectory information associated with the UE based on global positioning system (GPS) information of the UE, wherein the NTN cell among the plurality of NTN neighbor cells to perform at least one of the cell reselection or the CHO is selected further based on the determined ice time duration for each of the plurality of NTN neighbor cells and the determined trajectory information associated with the UE.
3 . The method of claim 2 , wherein the selecting of the NTN cell among the plurality of NTN neighbor cells comprises: ranking the service time duration for each of the plurality of NTN neighbor cells in a descending order, wherein a first NTN neighbor cell among the plurality of NTN neighbor cells has a first service time duration that is highest among other service time durations of other NTN neighbor cells of the plurality of NTN neighbor cells; determining, based on trajectory information associated with the first NTN neighbor cell and the determined trajectory information associated with the UE, whether a future interaction occurs between the first NTN neighbor cell and the UE; storing, in response to determining that the future interaction occurs between the first NTN neighbor cell and the UE, information associated with the future interaction which occurs between the first NTN neighbor cell and the UE in a database associated with the UE; determining, in response to determining that the future interaction occurs between the first NTN neighbor cell and the UE, one or more future interaction parameters associated with the first NTN neighbor cell; and selecting the NTN cell among the plurality of NTN neighbor cells based on the one or more determined future interaction parameters.
4 . The method of claim 3 , further comprising: detecting a second service time duration associated with a second NTN neighbor cell among the plurality of NTN neighbor cells, wherein the second service time duration is a next highest service time duration among other service time durations of other NTN neighbor cells of the plurality of NTN neighbor cells; determining, based on trajectory information associated with the second NTN neighbor cell and the determined trajectory information associated with the UE, whether a future interaction occurs between the second NTN neighbor cell and the UE; storing, in response to determining that the future interaction occurs between the second NTN neighbor cell and the UE, information associated with the future interaction which occurs between the second NTN neighbor cell and the UE in the database associated with the UE; determining, in response to determining that the future interaction occurs between the second NTN neighbor cell and the UE, one or more future interaction parameters associated with the first NTN neighbor cell and the second NTN neighbor; and selecting the NTN cell among the plurality of NTN neighbor cells based on the one or more determined future interaction parameters.
5 . The method of claim 4 , wherein the one or more determined future interaction parameters comprise at least one of a first service time value corresponding to the first NTN neighbor cell, a second service time value corresponding to the second NTN neighbor cell, a first-time value, a second-time value, a first difference value, or a second difference value.
6 . The method of claim 5 , wherein the first-time value represents an amount of time taken by the UE to reach at a first location associated with the first NTN neighbor cell, wherein the second-time value represents an amount of time taken by the UE to reach at a second location associated with the second NTN neighbor cell, wherein the first difference value indicates a difference between the first service time value for the first NTN neighbor cell and the first-time value, and wherein the second difference value indicates a difference between the second service time value for the second NTN neighbor cell and the second-time value.
7 . The method of claim 2 , wherein for determining the trajectory information associated with the UE, the method comprises: determining a position vector associated with the UE; determining a velocity vector associated with the UE; and determining the trajectory information associated with the UE based on the determined position vector and the determined velocity vector.
8 . The method of claim 1 , wherein the one or more system parameters comprise at least one of a service time value, a distance threshold, an NTN configuration, a reference location, an NTN uplink synchronization validity duration timer, ephemeris information (EphemerisInfo), or a rate of change of signal condition.
9 . The method of claim 1 , further comprising: determining, using the one or more system parameters, a service validity of a concerned satellite in the serving NTN cell and each of a position point and a trigger point for initiating at least one of an intra-frequency measurement or an inter-frequency measurement.
10 . The method of claim 1 , wherein the UE selects the NTN cell in at least one mode comprising a radio resource control (RRC) idle mode or an RRC connected mode.
11 . A user equipment (UE) for selecting a non-terrestrial network (NTN) cell, the UE comprising: a memory storing instructions; a communicator; and at least one processor, operably connected to the memory and the communicator, wherein when the at least one processor executes the instructions, the at least one processor causes the UE to perform operations comprising: receiving one or more system parameters from a serving NTN cell and a plurality of NTN neighbor cells, determining trajectory information associated with the plurality of NTN neighbor cells based on the one or more received system parameters, and selecting, based on the determined trajectory information associated with the plurality of NTN neighbor cells, the NTN cell among the plurality of NTN neighbor cells to perform at least one of a cell reselection or a conditional hand over (CHO).
12 . The UE of claim 11 , wherein the operations further comprises: determining a service time duration for each of the plurality of NTN neighbor cells ( 300 A, 300 B) based on the received one or more system parameters; and determining a trajectory information associated with the UE based on global positioning system, GPS, information of the UE, wherein the NTN cell among the plurality of NTN neighbor cells to perform at least one of the cell reselection or the CHO is selected further based on the determined ice time duration for each of the plurality of NTN neighbor cells and the determined trajectory information associated with the UE.
13 . The UE of claim 12 , wherein, the selecting of the NTN cell among the plurality of NTN neighbor cells comprises: ranking the service time duration for each of the plurality of NTN neighbor cells in a descending order, wherein a first NTN neighbor cell among the plurality of NTN neighbor cells has a first service time duration that is highest among other service time durations of other NTN neighbor cells of the plurality of NTN neighbor cells, determining, based on trajectory information associated with the first NTN neighbor cell and the determined trajectory information associated with the UE, whether a future interaction occurs between the first NTN neighbor cell and the UE, storing, in response to determining that the future interaction occurs between the first NTN neighbor cell and the UE, information associated with the future interaction which occurs between the first NTN neighbor cell and the UE in a database associated with the UE, determining, in response to determining that the future interaction occurs between the first NTN neighbor cell and the UE, one or more future interaction parameters associated with the first NTN neighbor cell, and selecting the NTN cell among the plurality of NTN neighbor cells based on the one or more determined future interaction parameters.
14 . The UE of claim 13 , wherein the operations further comprise: detecting a second service time duration associated with a second NTN neighbor cell among the plurality of NTN neighbor cells, wherein the second service time duration is a next highest service time duration among other service time durations of other NTN neighbor cells of the plurality of NTN neighbor cells, determining, based on trajectory information associated with the second NTN neighbor cell and the determined trajectory information associated with the UE, whether a future interaction occurs between the second NTN neighbor cell and the UE, storing, in response to determining that the future interaction occurs between the second NTN neighbor cell and the UE, information associated with the future interaction which occurs between the second NTN neighbor cell and the UE in the database associated with the UE, determining, in response to determining that the future interaction occurs between the second NTN neighbor cell and the UE, one or more future interaction parameters associated with the first NTN neighbor cell and the second NTN neighbor, and selecting the NTN cell among the plurality of NTN neighbor cells based on the one or more determined future interaction parameters.
15 . The UE of claim 14 , wherein the one or more determined future interaction parameters comprise at least one of a first service time value corresponding to the first NTN neighbor cell, a second service time value corresponding to the second NTN neighbor cell, a first-time value, a second-time value, a first difference value, or a second difference value.
16 . The UE of claim 15 , wherein the first-time value represents an amount of time taken by the UE to reach at a first location associated with the first NTN neighbor cell, wherein the second-time value represents an amount of time taken by the UE to reach at a second location associated with the second NTN neighbor cell, wherein the first difference value indicates a difference between the first service time value for the first NTN neighbor cell and the first-time value, and wherein the second difference value indicates a difference between the second service time value for the second NTN neighbor cell and the second-time value.
17 . The UE of claim 12 , wherein for determining the trajectory information associated with the UE, the operations comprise: determining a position vector associated with the UE; determining a velocity vector associated with the UE; and determining the trajectory information associated with the UE based on the determined position vector and the determined velocity vector.
18 . The UE of claim 11 , wherein the one or more system parameters comprise at least one of a service time value, a distance threshold, an NTN configuration, a reference location, an NTN uplink synchronization validity duration timer, ephemeris information (EphemerisInfo), or a rate of change of signal condition.
19 . The UE of claim 11 , wherein the operations further comprise: determining, using the one or more system parameters, a service validity of a concerned satellite in the serving NTN cell and each of a position point and a trigger point for initiating at least one of an intra-frequency measurement or an inter-frequency measurement.
20 . A non-transitory computer readable storage medium storing instructions which, when executed by at least one processor of a user equipment (UE), cause the UE to perform operations comprising: receiving one or more system parameters from a serving NTN cell and a plurality of NTN neighbor cells; determining trajectory information associated with the plurality of NTN neighbor cells based on the one or more received system parameters; and selecting, based on the determined trajectory information associated with the plurality of NTN neighbor cells, the NTN cell among the plurality of NTN neighbor cells to perform at least one of a cell reselection or a conditional hand over (CHO).
