Time alignment timer information

1. A method comprising:

transmitting, by a base station distributed unit to a wireless device, a timing advance command for a timing advance group;

starting, by the base station distributed unit and in response to transmitting the timing advance command, a time alignment timer in a medium access control (MAC) entity of the base station distributed unit for the timing advance group of the wireless device;

determining, by the MAC entity of the base station distributed unit, expiration of the time alignment timer in the MAC entity of the base station distributed unit;

transmitting, by the base station distributed unit to a radio resource control (RRC) layer of a base station central unit, a first message indicating the expiration of the time alignment timer for the timing advance group of the wireless device, wherein the base station central unit communicates with the wireless device via the base station distributed unit; and

applying, by the base station central unit and in response to receiving the first message, a default physical channel configuration for one or more cells of the timing advance group, wherein the default physical channel configuration comprises at least one of:

channel quality information report configurations;

uplink resource scheduling request configurations; or

dedicated uplink sounding reference signal configurations;

transmitting, by the base station central unit, the second message in response to the timing advance group being a primary timing advance group;

receiving, by the base station distributed unit and based on the first message, a second message indicating a wireless device context release request for the wireless device; and

releasing, by the base station distributed unit and in response to receiving the second message, a wireless device context of the wireless device, wherein the wireless device context comprises at least one of:

one or more data radio bearers;

one or more logical channels;

one or more security configuration parameters; or

one or more information associated with the wireless device.

2. The method of claim 1 , wherein the timing advance group comprises one or more cells.

3. The method of claim 1 , further comprising, by the base station distributed unit and in response to determining the expiration of the time alignment timer, at least one of:

releasing hybrid automated repeat request uplink resource configurations for one or more cells of the timing advance group;

releasing physical uplink control channel configurations for one or more cells of the timing advance group;

releasing sounding reference signal configurations for one or more cells of the timing advance group;

clearing configured downlink assignments for one or more cells of the timing advance group;

clearing uplink resource grants for one or more cells of the timing advance group; or

determining, in response to the timing advance group being a primary timing advance group, that a running time alignment timer for the timing advance group is expired.

4. The method of claim 1 , further comprising applying, by the base station distributed unit and in response to the expiration of the time alignment timer, a default physical channel configuration for one or more cells of the timing advance group, wherein the default physical channel configuration comprises at least one of:

channel quality information report configurations;

uplink resource scheduling request configurations;

or

dedicated uplink sounding reference signal configurations.

5. The method of claim 1 , further comprising releasing, by the base station distributed unit and based on the expiration of the time alignment timer, a wireless device context of the wireless device, wherein the wireless device context comprises at least one of:

one or more data radio bearers;

one or more logical channels;

one or more security configuration parameters; or

one or more information associated with the wireless device.

6. The method of claim 1 , further comprising transmitting, by the base station central unit to a core network entity and based on the first message, a third message indicating release of an interface connection for the wireless device between the base station central unit and the core network entity.

7. The method of claim 6 , further comprising transmitting, by the base station central unit, the third message in response to the timing advance group being a primary timing advance group.

8. The method of claim 6 , wherein the core network entity comprises at least one of: an access and mobility management function; or a mobility management function.

9. The method of claim 1 , further comprising releasing, by the base station central unit and based on the first message, a wireless device context of the wireless device, wherein the wireless device context comprises at least one of:

one or more data radio bearers;

one or more logical channels;

one or more security configuration parameters; or

one or more information associated with the wireless device.

10. The method of claim 1 , further comprising, by the base station central unit and in response to receiving the first message, at least one of:

releasing hybrid automated repeat request uplink resource configurations for one or more cells of the timing advance group;

releasing physical uplink control channel configurations for one or more cells of the timing advance group;

releasing sounding reference signal configurations for one or more cells of the timing advance group;

clearing configured downlink assignments for one or more cells of the timing advance group;

clearing uplink resource grants for one or more cells of the timing advance group; or

determining, in response to the timing advance group being a primary timing advance group, that a running time alignment timer for the timing advance group is expired.

11. The method of claim 1 , wherein:

the base station central unit comprises a radio resource control function for the wireless device; and

the base station distributed unit comprises at least one of:

a medium access control (MAC) layer function for the wireless device; or

a physical layer function for the wireless device.

12. The method of claim 1 , wherein the transmitting of the first message is via an F1 interface.

13. The method of claim 1 , wherein the transmitting of the timing advance command is via a medium access control (MAC) control element (CE).

14. The method of claim 1 , wherein the time alignment timer is configured by the base station central unit.

15. The method of claim 1 , wherein and the time alignment timer is configured by the base station distributed unit.

16. The method of claim 1 , further comprising transmitting, by the base station central unit to the wireless device, the time alignment timer via the base station distributed unit.

17. The method of claim 1 , wherein the first message further comprises at least one of:

an identifier of the wireless device;

one or more cell identifiers of one or more cells of the timing advance group; or

a timing advance group identifier of the timing advance group.