Method and apparatus for accessing base station in satellite communication system
A method for a user equipment (UE) to perform handover in a wireless communication system is provided. The method includes receiving, from a base station (BS), a first message indicating at least one condition for starting handover, wherein the at least one condition includes a condition based on a distance between the UE and a satellite used for current access; identifying whether the condition is satisfied based on a distance between the UE and the satellite used for current access; and performing a procedure for handover based on the condition being satisfied.
1. A method for a user equipment (UE) to perform handover in a wireless communication system, the method comprising:
receiving, from a base station (BS), a first message indicating at least one condition for starting handover, wherein the at least one condition includes a condition based on a distance between the UE and a satellite used for current access;
identifying whether the condition is satisfied based on a distance between the UE and the satellite used for current access; and
performing a procedure for handover based on the condition being satisfied.
2. The method of claim 1 , further comprising:
receiving, from the BS, information about a location of the satellite used for the current access.
3. The method of claim 2 , wherein the identifying of whether the condition is satisfied comprises:
determining the distance between the UE and the satellite used for current access based on the location of the satellite used for the current access; and
identifying whether the distance between the UE and the satellite used for current access is larger than a threshold.
4. The method of claim 3 , wherein the threshold is obtained based on the first message received from the BS.
5. The method of claim 2 , wherein the identifying of whether the condition is satisfied comprises:
determining an increase rate of the distance between the UE and the satellite used for current access based on the location of the satellite used for the current access; and
identifying whether the increase rate is larger than a threshold.
6. The method of claim 1 , wherein the first message is received through RRC signaling.
7. The method of claim 1 , wherein the performing of the procedure for handover comprises:
selecting a satellite to access for connecting a base station; and
connecting to the base station through the selected satellite.
8. The method of claim 7 , wherein the selecting of the satellite to access comprises selecting a satellite closest to the UE as the satellite to access.
9. The method of claim 7 , wherein the selecting of the satellite to access comprises selecting a satellite fastest approaching the UE as the satellite to access.
10. The method of claim 7 , wherein the selecting of the satellite to access comprises selecting a satellite predicted to be closest to the UE after a certain time as the satellite to access.
11. The method of claim 7 , wherein the selecting of the satellite to access comprises selecting a satellite with the least delay time to the BS as the satellite to access.
12. The method of claim 7 , wherein the selecting of the satellite to access comprises selecting a satellite to access based on information about a satellite to be selected during handover, the information being received from the BS.
13. The method of claim 7 , wherein the selecting of the satellite to access comprises:
receiving, from the BS, a message indicating a method for selecting a satellite to access; and
selecting a satellite to access according to the indicated method.
14. The method of claim 1 , wherein the identifying of whether the condition is satisifed is based on a predicted and precalculated distance between the satellite and the UE after a specific time point.
15. A user equipment (UE) in a wireless communication system, the UE comprising:
a transceiver; and
at least one processor configured to:
receive, from a base station (BS), a first message indicating at least one condition for starting handover, wherein the at least one condition includes a condition based on a distance between the UE and a satellite used for current access,
identify whether the condition is satisfied based on the distance between the UE and the satellite used for current access, and
perform a procedure for handover based on the condition being satisifed.
16. The UE of claim 15 , wherein the at least one processor is further configured to receive, from the BS, information about a location of the satellite used for the current access.
17. The UE of claim 15 , wherein the at least one processor is configured to identify whether the distance between the UE and the satellite used for current access is larger than a threshold.
18. The UE of claim 17 , wherein the threshold is obtained based on the first message received from the BS.
19. The UE of claim 15 , wherein the first message is received through RRC signaling.