RAN paging and RAN area identifier exchange between base stations

1. A method comprising:

receiving, by a first base station from a second base station, a cell identifier of a cell of the second base station, and a second radio access network (RAN) area identifier of the cell;

receiving, by the first base station from the second base station, a packet for a wireless device in a radio resource control (RRC) inactive state supporting a RAN paging; and

transmitting, by the first base station to the second base station, in response to receiving the packet, a RAN paging message based on a first RAN area identifier of the first base station and the second RAN area identifier.

2. The method of claim 1 , wherein the RAN paging message comprises an identifier of the wireless device and the first RAN area identifier.

3. The method of claim 1 , further comprising transmitting, by the first base station to the second base station, at least one of:

a first cell identifier of a first cell of the first base station; or

the first RAN area identifier of the first cell.

4. The method of claim 1 , further comprising:

transmitting, by the first base station to the wireless device, at least one RRC message comprising the first RAN area identifier,

wherein the at least one RRC message indicates a state transition of the wireless device to the RRC inactive state.

5. The method of claim 1 , wherein the transmitting the RAN paging message is further based on the wireless device being in the RRC inactive state.

6. The method of claim 1 , further comprising:

receiving, by the first base station from the second base station, a second message in response to the RAN paging message, wherein the second message indicates a wireless device context request; and

transmitting, by the first base station to the second base station, the packet for the wireless device in response to the second message.

7. The method of claim 1 , wherein the first base station keeps a wireless device context of the wireless device at least during a time in which the wireless device is in the RRC inactive state, the wireless device context comprising at least one of:

a bearer configuration information; or

a logical channel configuration information; or a security information.

8. The method of claim 1 , wherein the receiving the cell identifier of the cell and the second RAN area identifier of the cell comprises:

receiving the cell identifier of the cell and the second RAN area identifier of the cell via at least one of:

an interface setup request message;

an interface setup response message; or

a base station configuration update message.

9. The method of claim 1 , wherein the receiving the packet comprises receiving the packet from a core network entity.

10. The method of claim 1 , further comprising transmitting, by the first base station, one or more RAN paging messages to one or more third base stations associated with the first RAN area identifier.

11. A method comprising:

transmitting, by a second base station to a first base station, a cell identifier of a cell of the second base stations and a second radio access network (RAN) area identifier of the cell; and

receiving, by the second base station from the first base station, a RAN paging message for a wireless device based on a first RAN area identifier of the first base station and the second RAN area identifier,

wherein the wireless device is in a radio resource control (RRC) inactive state supporting a RAN paging.

12. The method of claim 11 , wherein the RAN paging message indicates a state transition of the wireless device from the RRC inactivate state to at least one of:

an RRC idle state; or

an RRC connected state.

13. The method of claim 11 , further comprising transmitting, by the second base station to the wireless device, one or more paging messages based on the RAN paging message.

14. The method of claim 11 , wherein the RAN paging message comprises an identifier of the wireless device and the first RAN area identifier.

15. The method of claim 11 , further comprising:

receiving, by the second base station from the first base station, at least one of:

a first cell identifier of a first cell of the first base station; or

the first RAN area identifier of the first cell.

16. The method of claim 11 ,

wherein the wireless device is in the RRC inactive state based on the wireless device receiving at least one RRC message that indicates a state transition of the wireless device to the RRC inactive state, and

wherein the at least one RRC message comprises the first RAN area identifier.

17. The method of claim 11 , wherein the receiving the RAN paging message is further based on the wireless device being in the RRC inactive state.

18. The method of claim 11 , further comprising:

transmitting, by the second base station to the first base station, a second message in response to the RAN paging message, wherein the second message indicates a wireless device context request; and

receiving, by the second base station from the first base station, a packet for the wireless device in response to the second message.

19. The method of claim 11 , wherein the first base station keeps a wireless device context of the wireless device at least during a time in which the wireless device is in the RRC inactive state, the wireless device context comprising at least one of:

a bearer configuration information;

a logical channel configuration information; or

a security information.

20. The method of claim 11 , wherein the transmitting the cell identifier of the cell and the second RAN area identifier of the cell comprises transmitting the cell identifier of the cell and the second RAN area identifier of the cell via at least one of:

an interface setup request message;

an interface setup response message; or

a base station configuration update message.