Small data transmission

1. A method comprising:

receiving, by a first base station from a second base station, a request for a context of a wireless device, wherein the request comprises assistance information for a small data transmission (SDT) procedure of the wireless device, the assistance information indicating whether:

single data associated with the SDT procedure is expected; or

more than single data associated with the SDT procedure is expected.

2. The method of claim 1 , further comprising sending, by the first base station, to a wireless device, a first radio resource control (RRC) message indicating a suspension of a RRC connection of the wireless device.

3. The method of claim 2 , wherein the first RRC message comprises at least one of:

a resume wireless device identity of the wireless device;

a next hop chaining count;

radio access network, RAN, notification area information; and

period RAN-based notification area update timer value.

4. The method of claim 1 , further comprising determining, by the first base station and based on the assistance information, whether to keep the context of the wireless device.

5. The method of claim 4 , further comprising:

determining to keep the context of the wireless device based on no further uplink or downlink data transmission being expected; and

determining to not keep the context of the wireless device based on more than a single uplink or single downlink data transmission being expected.

6. The method of claim 1 , further comprising sending, by the first base station to the second base station, based on determining to keep the context of the wireless device, a second RRC message indicating a release or a suspension of the RRC connection.

7. The method of claim 1 , further comprising sending, by the first base station to the second base station, based on determining to not keep the context of the wireless device, the context of the wireless device.

8. The method of claim 1 , wherein the assistance information comprises a data radio bearer identity associated with the SDT procedure.

9. The method of claim 8 , further comprising:

determining to keep the context of the wireless device based on a data radio bearer associated with the data radio bearer identity being configured for small data transmission; and

determining to not keep the context of the wireless device based on the data radio bearer associated with the data radio bearer identity being not configured for small data transmission.

10. The method of claim 1 , wherein the assistance information comprises application information associated with the SDT procedure.

11. A first base station comprising:

one or more processors; and

memory storing instructions that, when executed by the one or more processors, cause the first base station to perform operations comprising:

receiving, from a second base station, a request for a context of a wireless device, wherein the request comprises assistance information for a small data transmission (SDT) procedure of the wireless device, the assistance information indicating whether:

single data associated with the SDT procedure is expected; or

more than single data associated with the SDT procedure is expected.

12. The first base station of claim 11 , wherein the operations further comprise sending, to a wireless device, a first radio resource control (RRC) message indicating a suspension of a RRC connection of the wireless device.

13. The first base station of claim 12 , wherein the first RRC message comprises at least one of:

a resume wireless device identity of the wireless device;

a next hop chaining count;

radio access network, RAN, notification area information; and

period RAN-based notification area update timer value.

14. The first base station of claim 11 , wherein the operations further comprise determining, based on the assistance information, whether to keep the context of the wireless device.

15. The first base station of claim 14 , wherein the operations further comprise:

determining to keep the context of the wireless device based on no further uplink or downlink data transmission being expected; and

determining to not keep the context of the wireless device based on more than a single uplink or single downlink data transmission being expected.

16. The first base station of claim 11 , wherein the operations further comprise sending, to the second base station, based on determining to keep the context of the wireless device, a second RRC message indicating a release or a suspension of the RRC connection.

17. The first base station of claim 11 , wherein the operations further comprise sending, to the second base station, based on determining to not keep the context of the wireless device, the context of the wireless device.

18. The first base station of claim 11 , wherein the assistance information comprises a data radio bearer identity associated with the SDT procedure.

19. The first base station of claim 18 , wherein the operations further comprise:

determining to keep the context of the wireless device based on a data radio bearer associated with the data radio bearer identity being configured for small data transmission; and

determining to not keep the context of the wireless device based on the data radio bearer associated with the data radio bearer identity being not configured for small data transmission.

20. A system comprising:

a first base station comprising: one or more processors and memory storing instructions that, when executed by the one or more processors, cause the first base station to perform operations comprising:

receiving, from a second base station, a request for a context of a wireless device, wherein the request comprises assistance information for a small data transmission (SDT) procedure of the wireless device, the assistance information indicating whether:

single data associated with the SDT procedure is expected; or

more than single data associated with the SDT procedure is expected; and

the second base station, wherein the second base station comprises: one or more processors and memory storing instructions that, when executed by the one or more processors, cause the second base station to:

send the request for the context of the wireless device.