Radio resource control connection resume method of wireless communication system

1. A radio resource control (RRC) connection resume method of a wireless communication system, the RRC connection resume method comprising:

receiving, by a user equipment (UE), an RRC suspend message from a first base station, wherein the RRC suspend message comprises:

target cell information; and

target radio access technology information comprising numerology information.

2. The RRC connection resume method of claim 1 , further comprising:

performing, by the UE, an RRC resume procedure with a second base station in response to the RRC suspend message; and

receiving, by the UE, an RRC resume response from the second base station,

wherein the RRC suspend message further comprises area information.

3. The RRC connection resume method of claim 2 , further comprising:

transmitting, by the second base station, a UE context fetch request to the first base station in response to the RRC resume procedure; and

receiving, by the second base station, a UE context fetch response from the first base station in response to the UE context fetch request,

wherein the first base station and the second base station are realized by different radio access numerologies, one of the first base station and the second base station is realized by a wide-band numerology and the other one of the first base station and the second base station is realized by a narrow-band-Internet-of-Things numerology.

4. The RRC connection resume method of claim 2 , further comprising:

transmitting, by the second base station, a UE context fetch request to the first base station in response to the RRC resume procedure; and

receiving, by the second base station, a UE context fetch response from the first base station in response to the UE context fetch request,

wherein the first base station and the second base station are realized by different radio access technologies, and one of the first base station and the second base station is realized by a narrow-band-Internet-of-Things numerology.

5. The RRC connection resume method of claim 2 , wherein performing the RRC resume procedure with the second base station comprises:

transmitting, by the UE, an RRC resume request to the second base station,

wherein the RRC resume request comprises at least one of:

an RRC resume request cause; and

source cell information.

6. The RRC connection resume method of claim 2 , wherein the RRC resume response comprises at least one of:

a data packet acknowledgement (ACK) or Non-acknowledgement (NACK); and

an area update response.

7. The RRC connection resume method of claim 2 , further comprising:

transmitting, by the UE, an area update request to the second base station;

performing, by the second base station, an area update procedure with other network entities when the area update request is received;

receiving, by the UE, an area update response from the second base station.

8. The RRC connection resume method of claim 1 , wherein the RRC suspend message further comprises an RRC resume validity timer and area information, and the RRC connection resume method further comprises:

starting, by the UE, the RRC resume validity timer when the RRC resume validity timer in the RRC suspend message is received; and

removing, by the UE, at least a part of UE context when the RRC resume validity timer expires.

9. A user equipment (UE) comprising:

one or more non-transitory computer-readable media having computer-executable instructions embodied thereon;

at least one processor coupled to the one or more non-transitory computer-readable media, and configured to execute the computer-executable instructions to:

receive a radio resource control (RRC) suspend message from a first base station, wherein the RRC suspend message comprises:

target cell information; and

target radio access technology information comprising numerology information.

10. The UE of claim 9 , wherein:

the RRC suspend message further comprises area information, and

the at least one processor is further configured to execute the computer-executable instructions to:

perform an RRC resume procedure with a second base station in response to the RRC suspend message; and

receive an RRC resume response from the second base station.

11. The UE of claim 10 , wherein the at least one processor is further configured to execute the computer-executable instructions to:

transmit an RRC resume request to the second station,

wherein the RRC resume request comprises at least one of:

an RRC resume request cause; and

source cell information.

12. The UE of claim 10 , wherein the RRC resume response comprises at least one of:

a data packet acknowledgement (ACK) or Non-acknowledgement (NACK); and

an area update response.

13. The UE of claim 10 , wherein the at least one processor is further configured to execute the computer-executable instructions to:

transmit an area update request to the second base station; and

receive an area update response from the second base station.

14. The UE of claim 9 , wherein:

the RRC suspend message further comprises an RRC resume validity timer and area information; and

the at least one processor is further configured to execute the computer-executable instructions to:

start the RRC resume validity timer when the RRC resume validity timer in the RRC suspend message is received; and

remove at least a part of UE context when the RRC resume validity timer expires.

15. A base station comprising:

one or more non-transitory computer-readable media having computer-executable instructions embodied thereon;

at least one processor coupled to the one or more non-transitory computer-readable media, and configured to execute the computer-executable instructions to:

transmit a radio resource control (RRC) suspend message to a user equipment (UE), wherein the RRC suspend message comprises:

target cell information; and

target radio access technology information comprising numerology information.

16. The base station of claim 15 , wherein:

the RRC suspend message further comprises area information, and

the at least one processor is further configured to execute the computer-executable instructions to:

receive a UE context fetch request from another base station; and

transmit a UE context fetch response to the another base station in response to the UE context fetch request.

17. The base station of claim 16 , wherein the base station and the another base station are realized by different radio access numerologies, one of the base station and the another base station is realized by a wide-band numerology and the other one of the first base station and the second base station is realized by a narrow-band-Internet-of-Things numerology.

18. The base station of claim 16 , wherein the base station and the another base station are realized by different radio access technologies, and one of the base station and the another base station is realized by a narrow-band-Internet-of-Things numerology.

19. The base station of claim 16 , wherein the at least one processor is further configured to execute the computer-executable instructions to:

receive an area update request from the another base station; and

transmit an area update response to the another base station in response to the area update request.

20. The base station of claim 15 , wherein the RRC suspend message further comprises an RRC resume validity timer and area information, and the at least one processor is further configured to execute the computer-executable instructions to:

start the RRC resume validity timer when the RRC resume validity timer in the RRC suspend message is transmitted; and

remove at least a part of UE context when the RRC resume validity timer expires.