Mobility management for RRC_INACTIVE user equipment

1. A method for radio access network (RAN) based notification area (RNA) update for a radio resource control (RRC) INACTIVE user equipment (UE) in an RRC_INACTIVE state, the method comprising:

receiving, by the RRC_INACTIVE UE in the RRC_INACTIVE state, a first list of RAN area IDs from a first cell via a first RRC message;

storing, by the RRC_INACTIVE UE in the RRC_INACTIVE state, the first list of RAN area IDs after receiving the first RRC message;

receiving, by the RRC_INACTIVE UE in the RRC_INACTIVE state, a cell ID and a RAN area ID broadcast by a second cell;

initiating, by the RRC_INACTIVE UE in the RRC_INACTIVE state, an RNA update procedure, when the RRC_INACTIVE UE in the RRC_INACTIVE state determines that the RAN area ID broadcast by the second cell does not belong to the first list of RAN area IDs stored in the RRC_INACTIVE UE in the RRC_INACTIVE state;

receiving, by the RRC_INACTIVE UE in the RRC_INACTIVE state, a second list of RAN area IDs from the second cell via a second RRC message during the RNA update procedure;

storing the second list of RAN area IDs by the RRC_INACTIVE UE in the RRC_INACTIVE state during the RNA update procedure after receiving the second RRC message; and

performing, by the RRC_INACTIVE UE in the RRC_INACTIVE state, a random access procedure with the second cell;

wherein the RRC_INACTIVE UE in the RRC_INACTIVE state sends at least one of an inactive-radio network temporary identifier (I-RNTI) and a cell ID of the first cell to the second cell.

2. The method of claim 1 , wherein, when the cell ID or the RAN area ID broadcast by the second cell does not match any of a list of cell IDs or the first list of RAN area IDs stored in the RRC_INACTIVE UE in the RRC_INACTIVE state, the RRC_INACTIVE UE in the RRC_INACTIVE state determines that the RRC_INACTIVE UE in the RRC_INACTIVE state is moving from a first RNA to a second RNA.

3. The method of claim 1 , further comprising:

sending, by the second cell, at least one of the I-RNTI and a cell ID of the second cell to the first cell; and

storing, by the first cell, the cell ID of the second cell.

4. The method of claim 3 , further comprising:

sending, by the first cell, a UE-specific RNA request to a core network (CN), wherein the UE-specific RNA request includes at least one of a UE ID of the RRC_INACTIVE UE in the RRC_INACTIVE state, the cell ID of the second cell, and a security key.

5. The method of claim 4 , further comprising:

sending, by the first cell, an RNA response to the second cell; and

sending, by the CN, a UE-specific RNA response to the second cell;

wherein, when a security key included in the RNA response from the first cell matches a security key included in the UE-specific RNA response from the CN, the second cell sends the second list of RAN area IDs included in the UE-specific RNA response from the CN to the RRC_INACTIVE UE in the RRC_INACTIVE state.

6. The method of claim 4 , further comprising:

sending, by the CN, a UE-specific RNA response to the first cell, the UE-specific RNA response having the second list of RAN area IDs;

sending, by the first cell, an RNA response to the second cell, the RNA response having the second list of RAN area IDs; and

sending, by the second cell, the second list of RAN area IDs to the RRC_INACTIVE UE in the RRC_INACTIVE state.

7. The method of claim 3 , further comprising:

sending, by the first cell, an RNA response to the second cell, the RNA response having the second list of RAN area IDs; and

sending, by the second cell, the second list of RAN area IDs to the RRC_INACTIVE UE in the RRC_INACTIVE state.

8. The method of claim 1 , further comprising:

receiving, by the RRC_INACTIVE UE in the RRC_INACTIVE state, from at least one of the first cell and the second cell an updated RNA having at least one of the following:

a list of cell IDs;

a list of cells;

a list of RAN areas; and

a list of tracking area IDs.

9. The method of claim 1 , wherein the second list of RAN area IDs is determined by at least one of the first cell, the second cell, and a core network (CN), based on a tracking area of the RRC_INACTIVE UE in the RRC_INACTIVE state.

10. The method of claim 1 , further comprising:

performing, by the RRC_INACTIVE UE in the RRC_INACTIVE state, a random access procedure with the second cell;

wherein the RRC_INACTIVE UE in the RRC_INACTIVE state sends at least one of an inactive-radio network temporary identifier (I-RNTI) and a cell ID of a third cell to the second cell, the third cell storing a UE context of the RRC_INACTIVE UE in the RRC_INACTIVE state.

11. The method of claim 10 , further comprising:

sending, by the second cell, at least one of the I-RNTI and a cell ID of the second cell to the third cell.

12. The method of claim 11 , further comprising:

sending, by the third cell, a UE-specific RNA request to a core network (CN), wherein the UE-specific RNA request includes at least one of a UE ID of the RRC_INACTIVE UE in the RRC_INACTIVE state, the cell ID of the second cell, and a security key.

13. The method of claim 12 , further comprising:

sending, by the third cell, an RNA response to the second cell; and

sending, by the CN, a UE-specific RNA response to the second cell;

wherein, when a security key included in the RNA response from the third cell matches a security key included in the UE-specific RNA response from the CN, the second cell sends the second list of RAN area IDs included in the UE-specific RNA response from the CN to the RRC_INACTIVE UE in the RRC_INACTIVE state.

14. The method of claim 12 , further comprising:

sending, by the second cell, a UE Assistance Delete message having the I-RNTI to the first cell to delete information of the RRC_INACTIVE UE in the RRC_INACTIVE state stored in the first cell; and

sending, by the first cell, a UE Assistance Delete Confirm message having the I-RNTI to the second cell when the information of the RRC_INACTIVE UE in the RRC_INACTIVE state stored in the first cell is deleted from the first cell.

15. A user equipment (UE) for wireless communication, the 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 first list of RAN area IDs from a first cell via a first radio resource control (RRC) message while the UE is in an RRC_INACTIVE state;

store the first list of RAN area IDs after receiving the first RRC message;

receive a cell ID and a RAN area ID broadcast by a second cell, while the UE is in the RRC_INACTIVE state;

initiate a radio access network (RAN) based notification area (RNA) update procedure, when the UE in the RRC_INACTIVE state determines that the RAN area ID broadcast by the second cell does not belong to the first list of RAN area IDs stored in the UE in the RRC_INACTIVE state;

receive a second list of RAN area IDs from the second cell via a second RRC message during the RNA update procedure, while the UE is in the RRC_INACTIVE state;

store the second list of RAN area IDs during the RNA update procedure after receiving the second RRC message, while the UE is in the RRC_INACTIVE state; and

perform a random access procedure with the second cell;

wherein the UE in the RRC_INACTIVE state sends at least one of an inactive-radio network temporary identifier (I-RNTI) and a cell ID of the first cell to the second cell.

16. The UE of claim 15 , wherein, when the cell ID or the RAN area ID broadcast by the second cell does not match any of a list of cell IDs or the first list of RAN area IDs stored in the UE in the RRC_INACTIVE state, the UE in the RRC_INACTIVE state determines that the UE in the RRC_INACTIVE state is moving from a first RNA to a second RNA.

17. The UE of claim 15 , wherein:

the second cell sends at least one of the I-RNTI and a cell ID of the second cell to the first cell; and

the first cell sends a UE-specific RNA request to a core network (CN), wherein the UE-specific RNA request includes at least one of a UE ID of the UE in the RRC_INACTIVE state, the cell ID of the second cell, and a security key.

18. The UE of claim 17 , wherein:

the first cell sends an RNA response to the second cell; and

the CN sends a UE-specific RNA response to the second cell;

when a security key included in the RNA response from the first cell matches a security key included in the UE-specific RNA response from the CN, the UE in the RRC_INACTIVE state receives from the second cell the second list of RAN area IDs included in the UE-specific RNA response from the CN.

19. The UE of claim 17 , wherein:

the CN sends a UE-specific RNA response to the first cell, the UE-specific RNA response having the second list of RAN area IDs;

the first cell sends an RNA response to the second cell, the RNA response having the second list of RAN area IDs; and

the UE in the RRC_INACTIVE state receives the second list of RAN area IDs from the second cell.

20. The UE of claim 17 , wherein:

the first cell sends an RNA response to the second cell, the RNA response having the second list of RAN area IDs; and

the UE in the RRC_INACTIVE state receives the second list of RAN area IDs from the second cell.

21. The UE of claim 15 , wherein the at least one processor is configured to execute the computer-executable instructions to receive from at least one of the first cell and the second cell an updated RNA having at least one of the following:

a list of cell IDs;

a list of cells;

a list of RAN areas; and

a list of tracking area IDs.

22. The UE of claim 15 , wherein the second list of RAN area IDs is determined by at least one of the first cell, the second cell, and a core network (CN), based on a tracking area of the UE in the RRC_INACTIVE state.