Apparatus, method, and computer program for connection management

1. An apparatus comprising:

at least one processor; and

at least one memory storing instructions thereon that, when executed by the at least one processor, cause the apparatus to perform at least:

in response to receiving a fallback indication from a radio resource control layer, when the apparatus has no pending non-access stratum procedure and has pending uplink user data:

invoking a service request procedure;

setting an uplink data status information element (IE) in a service request message to indicate one or more packet data unit (PDU) sessions for which user-plane resources were active prior to receiving the fallback indication; and

setting a service type information element in the service request message to “emergency services” if the uplink data status IE indicates an emergency PDU session, or to “data” if the uplink data status IE indicates no emergency PDU session.

2. The apparatus of claim 1 , wherein the instructions stored on the at least one memory, when executed by the at least one processor, further cause the apparatus to perform at least:

determining that the apparatus has pending uplink user data and has no pending non-access stratum procedure.

3. The apparatus of claim 1 , wherein the apparatus is in a connected mode.

4. The apparatus of claim 1 , wherein the apparatus is in a connected inactive mode.

5. The apparatus of claim 1 , wherein at least one of the receiving, the determining, the invoking or the setting is performed at a non-access stratum layer.

6. A method performed by an apparatus, the method comprising:

in response to receiving a fallback indication from a radio resource control layer, when the apparatus has no pending non-access stratum procedure and has pending uplink user data:

invoking a service request procedure;

setting an uplink data status information element (IE) in a service request message to indicate one or more packet data unit (PDU) sessions for which user-plane resources were active prior to receiving the fallback indication; and

setting a service type information element in the service request message to “emergency services” if the uplink data status IE indicates an emergency PDU session, or to “data” if the uplink data status IE indicates no emergency PDU session.

7. The method of claim 6 , further comprising:

determining that the apparatus has pending uplink user data and has no pending non-access stratum procedure.

8. The method of claim 6 , wherein the apparatus is in a connected mode or in a connected inactive mode.

9. A computer program product with a non-transitory computer readable medium comprising computer executable instructions which, when run on one or more processors, perform at least:

in response to receiving a fallback indication from a radio resource control layer, when an apparatus has no pending non-access stratum procedure and has pending uplink user data:

invoking a service request procedure;

setting an uplink data status information element (IE) in a service request message to indicate one or more packet data unit (PDU) sessions for which user-plane resources were active prior to receiving the fallback indication; and

setting a service type information element in the service request message to “emergency services” if the uplink data status IE indicates an emergency PDU session, or to “data” if the uplink data status IE indicates no emergency PDU session.

10. The apparatus of claim 1 , wherein the instructions stored on the at least one memory, when executed by the at least one processor, further cause the apparatus to perform at least:

in response to receiving the fallback indication,

when the apparatus has a pending non-access stratum procedure other than a registration procedure, a service request procedure, or a de-registration procedure:

invoking the service request procedure; and

setting a service type IE in the service request message to “emergency services” if a message for the pending non-access stratum procedure is an uplink non-access stratum transport message including a request type IE set to “initial emergency request” or “existing emergency PDU session”, or to “signalling” otherwise.

11. The apparatus of claim 10 , wherein the instructions stored on the at least one memory, when executed by the at least one processor, further cause the apparatus to perform at least:

setting the uplink data status IE in the service request message to indicate one or more PDU sessions for which user-plane resources were active prior to receiving the fallback indication, when the apparatus in connected mode has the pending non-access stratum procedure other than the service request procedure.

12. The apparatus of claim 10 , wherein the instructions stored on the at least one memory, when executed by the at least one processor, further cause the apparatus to perform at least:

setting the uplink data status IE in the service request message to indicate one or more always-on PDU sessions, when the apparatus in connected inactive mode has the pending non-access stratum procedure other than the service request procedure.

13. The apparatus of claim 10 , wherein the instructions stored on the at least one memory, when executed by the at least one processor, further cause the apparatus to perform at least:

determining that the apparatus has the pending non-access stratum procedure other than the registration procedure, the service request procedure or the deregistration procedure.

14. The apparatus of claim 1 , wherein the instructions stored on the at least one memory, when executed by the at least one processor, further cause the apparatus to perform at least:

in response to receiving the fallback indication,

when the apparatus has a pending service request procedure invoked due to other than an emergency service fallback:

invoking the service request procedure; and

setting the service type IE in the service request message to “mobile terminated services”, “high priority access”, “emergency services” or “data” if the apparatus has the pending service request procedure due to other than an emergency service fallback.

15. The apparatus of claim 14 , wherein the instructions stored on the at least one memory, when executed by the at least one processor, further cause the apparatus to perform at least:

setting the uplink data status IE in the service request message to indicate one or more PDU sessions for which user-plane resources were not active prior to receiving the fallback indication and the apparatus has pending user data to be sent over a cellular network when the apparatus has the pending service request procedure invoked due to other than the emergency service fallback.

16. The apparatus of claim 14 , wherein the instructions stored on the at least one memory, when executed by the at least one processor, further cause the apparatus to perform at least:

determining that the apparatus has the pending service request procedure invoked due to other than the emergency service fallback.

17. The apparatus of claim 1 , wherein the instructions stored on the at least one memory, when executed by the at least one processor, further cause the apparatus to perform at least:

in response to receiving the fallback indication,

when the apparatus has a pending service request procedure invoked due to an emergency service fallback:

invoking the service request procedure; and

setting the service type IE in the service request message to “emergency services fallback” if the apparatus has the pending service request procedure due to the emergency service fallback.

18. The apparatus of claim 1 , wherein the apparatus comprises a user equipment.

19. The method of claim 6 , further comprising:

in response to receiving the fallback indication,

when the apparatus has a pending non-access stratum procedure other than a registration procedure, a service request procedure, or a de-registration procedure:

invoking the service request procedure; and

setting a service type IE in the service request message to “emergency services” if a message for the pending non-access stratum procedure is an uplink non-access stratum transport message including a request type IE set to “initial emergency request” or “existing emergency PDU session”, or to “signalling” otherwise.

20. The method of claim 19 , further comprising:

setting the uplink data status IE in the service request message to indicate one or more PDU sessions for which user-plane resources were active prior to receiving the fallback indication, when the apparatus in connected mode has the pending non-access stratum procedure other than the service request procedure.

21. The method of claim 19 , further comprising:

setting the uplink data status IE in the service request message to indicate one or more always-on PDU sessions, when the apparatus in connected inactive mode has the pending non-access stratum procedure other than the service request procedure.

22. The method of claim 19 , further comprising:

determining that the apparatus has the pending non-access stratum procedure other than the registration procedure, the service request procedure or the deregistration procedure.

23. The method of claim 6 , further comprising:

in response to receiving the fallback indication,

when the apparatus has a pending service request procedure invoked due to other than an emergency service fallback:

invoking the service request procedure; and

setting the service type IE in the service request message to “mobile terminated services”, “high priority access”, “emergency services” or “data” if the apparatus has the pending service request procedure due to other than an emergency service fallback.

24. The method of claim 23 , further comprising:

setting the uplink data status IE in the service request message to indicate one or more PDU sessions for which user-plane resources were not active prior to receiving the fallback indication and the apparatus has pending user data to be sent over a cellular network when the apparatus has the pending service request procedure invoked due to other than the emergency service fallback.

25. The method of claim 23 , further comprising:

determining that the apparatus has the pending service request procedure invoked due to other than the emergency service fallback.

26. The method of claim 23 , further comprising:

in response to receiving the fallback indication,

when the apparatus has a pending service request procedure invoked due to an emergency service fallback:

invoking the service request procedure; and

setting the service type IE in the service request message to “emergency services fallback” if the apparatus has the pending service request procedure due to the emergency service fallback.

27. The method of claim 6 , wherein the apparatus comprises a user equipment.

28. The method of claim 6 , wherein at least one of; the receiving, the determining, the invoking, or the setting is performed at a non-access stratum layer.

29. The apparatus of claim 1 , wherein said invoking the service request procedure is in response to receiving, over a third-generation partnership project (3GPP) access, a NOTIFICATION message with an access type information element (IE) indicating non-3GPP access.

30. The apparatus of claim 1 , wherein said invoking the service request procedure is in response to the apparatus being in a connected mode or a connected inactive mode, and the apparatus having user data pending due to a non-user plane resource established for protocol data unit (PDU) sessions being used for data transport.