Enable a network-trigger change of network slices

1. A method for wireless communication at a source access and mobility management function (AMF), comprising:

determining to modify current-allowed network slices supported for a user equipment (UE) based at least in part on a network-trigger;

identifying a new-allowed network slice supported for the UE based at least in part on the determining;

determining that the source AMF is unable to serve the new-allowed network slice;

transmitting an indication to the UE to initiate a registration procedure, based at least in part on the determining that the source AMF is unable to serve the new-allowed network slice;

selecting a target AMF based at least in part on the transmitting, wherein the target AMF is associated with the new-allowed network slice; and

triggering an AMF relocation based at least in part on the selecting.

2. The method of claim 1 , further comprising:

determining that the UE has an active network slice instance (NSI) associated with at least one network selection assistance information (NSSAI); and

identifying that an active NSI is supported by the new-allowed network slices.

3. The method of claim 2 , further comprising:

generating a status report indicating a status of all existing protocol data unit (PDU) sessions associated with the active NSI.

4. The method of claim 2 , wherein triggering the AMF relocation further comprising:

transmitting an AMF relocation request to the target AMF based at least in part on the new-allowed network slices, wherein the AMF relocation request comprises a status of all existing PDU session associated with the active NSI that are supported and active, or a new radio (NR) globally unique temporary identifier (GUTI), or both.

5. The method of claim 1 , further comprising:

triggering a release procedure of an active protocol data unit (PDU) session associated with the current-allowed network slices based at least in part on identifying that the active PDU session is unsupported by the new-allowed network slices.

6. The method of claim 5 , wherein triggering the release procedure is based at least in part on direct signaling to the UE.

7. The method of claim 1 , further comprising:

determining to modify current-allowed network slices used by a UE based at least in part on a received network-trigger;

identifying new-allowed network slices for the UE based at least in part on the determining; and

determining that a target AMF associated with the new-allowed network slices is inaccessible by the source AMF.

8. The method of claim 7 , further comprising:

transmitting a de-registration request to the UE based at least in part on determining that the target AMF is inaccessible by the source AMF.

9. The method of claim 8 , wherein the de-registration request comprises an indication to perform a re-registration procedure, the new-allowed network slices, or a code indicating that the de-registration request is in response to a change of supported network slices, or a combination thereof.

10. The method of claim 8 , further comprising:

triggering a release procedure of an active protocol data unit (PDU) session associated with current-allowed network slices that are unsupported by the new-allowed network slices; and

releasing UE context comprising a status report of active PDU session or a new radio (NR) globally unique temporary identifier (GUTI), or both based at least in part on the triggering.

11. A method for wireless communication at a user equipment (UE), comprising:

receiving, from a source access and mobility management function (AMF), a configuration message comprising an identifier associated with a target AMF, a status of existing active protocol data unit (PDU) sessions of the UE, a new-allowed network slice, or an indication to initiate a registration procedure, or a combination thereof;

initiating a registration procedure based at least in part on the receiving;

identifying an active PDU session based at least in part on the receiving, wherein the active PDU session is unsupported by the new-allowed network slice; and

locally releasing the active PDU session based at least in part on the initiating.

12. The method of claim 11 , wherein the identifier comprises a new radio (NR) globally unique temporary identifier (GUTI).

13. The method of claim 11 , further comprising:

identifying a re-registration request and a code indicating a request to register a set of network slices associated with a new-allowed network slice based at least in part on a received de-registration request from a source access and management function (AMF) that is serving the UE;

identifying the new-allowed network slices based at least in part on the received de-registration request.

14. The method of claim 13 , further comprising:

generating a request for registering the set of network slices associated with a new-allowed network slice based at least in part on the code, wherein the initiating is associated with the generating.

15. The method of claim 13 , further comprising:

storing information associated with the new-allowed network slices, wherein the information comprises NSSAI.

16. A method for wireless communication at an access network (AN), comprising:

receiving, from a user equipment (UE), a radio resource control (RRC) connection request comprising network slice selection assistance information (NSSAI);

identifying a source access and management function (AMF) associated with current-allowed network slices of the UE based at least in part on the NSSAI;

determining to modify the NSSAI based at least in part on a trigger indication;

identifying a new-allowed network slice supported for the UE based at least in part on the determining;

determining that the source AMF is unable to serve the new-allowed network slice;

receiving a request to initiate a re-registration procedure based at least in part on the source AMF being unable to serve the new-allowed network slice;

selecting a target AMF to serve the UE based at least in part on the request; and

triggering an AMF relocation based at least in part on the selecting.

17. The method of claim 16 wherein signaling the source AMF comprises:

transmitting an indication comprising information for selection of the target AMF for redirecting the RRC connection request; and

transmitting instructions for performing the redirecting via the source AMF.

18. The method of claim 17 , wherein the instructions for performing the redirecting correspond to signaling between the source AMF and the target AMF via the AN.

19. The method of claim 17 , wherein the instructions for performing the redirecting correspond to signaling between the source AMF and the target AMF via direct signaling.

20. The method of claim 16 , wherein the trigger indication comprises a policy control function (PCF) indication, an indication designating a change in a subscription of one or more current-allowed network slices, or a combination thereof.

21. The method of claim 16 , further comprising:

establishing an N2 signaling connection with the target AMF; and

transmitting a NAS message received from the UE to the target AMF using the N2 signaling connection.

22. The method of claim 21 , further comprising:

transmitting, to the source AMF, a request to release an N2 signaling connection.

23. The method of claim 21 , further comprising:

receiving, from the target AMF, an updated NR globally unique temporary identifier (GUTI) for the UE; and

replacing a previous NR GUTI with the received updated NR GUTI for the UE.

24. A method for wireless communication at an access network (AN), comprising:

determining to modify the network slice selection assistance information (NSSAI) based at least in part on a trigger indication;

identifying a new-allowed network slice supported for the UE based at least in part on the determining;

determining that a source access and management function (AMF) associated with current-allowed network slices is unable to serve the new-allowed network slice;

identifying a re-registration request;

selecting a target AMF to serve the UE based at least in part on the re-registration request, wherein the target AMF is associated with the new-allowed network slice; and

triggering an AMF relocation based at least in part on the selecting, wherein the AMF relocation comprises initiating a redirection of the UE from the source AMF to the target AMF.

25. The method of claim 24 , wherein the request for relocation comprises context information for at least one of the new-allowed network slices, the UE, or the target AMF.

26. The method of claim 24 , further comprising:

receiving, from the target AMF, an updated NR globally unique temporary identifier (GUTI) for the UE; and

replacing a previous NR GUTI with the received updated NR GUTI for the UE.

27. The method of claim 24 , further comprising:

transmitting, to the UE, a configuration request message comprising the updated NR GUTI, a status of existing active protocol data unit (PDU) sessions of the UE, indication of the modifying to the NSSAI, or a combination thereof.

28. The method of claim 24 , wherein the trigger indication comprises a policy control function (PCF) indication, an indication designating a change in a subscription of one or more current-allowed network slices, or a combination thereof.

29. The method of claim 24 , wherein the redirection of the UE is based at least in part on an operator policy.

30. The method of claim 1 , wherein the indication to the UE to initiate a registration procedure comprises an indication to perform a re-registration request.