4.6.2.11 Mobility management for partial network slice

A serving PLMN or SNPN can indicate the S-NSSAI(s) is allowed or rejected in some TA(s) but not all TAs of the registration area to the UE during the registration procedure as specified in clause 5.5.1 and the generic UE configuration update procedure as specified in clause 5.4.4. The support for the partial network slice by a UE or an AMF is optional.

If the UE supports the partial network slice and includes the S-NSSAI(s) in the requested NSSAI and:

• if the S-NSSAI(s) is allowed in the current TA but not all TAs of the registration area, and
• if the S-NSSAI(s) is subject to NSAC for the maximum number of UEs, the AMF should include the S-NSSAI(s) in the allowed NSSAI to the UE and limit the registration area so that the S-NSSAI(s) is allowed in all the TAs of the registration area;
• if the S-NSSAI(s) is subject to NSSAA, the AMF shall include the S-NSSAI(s) in:
• the pending NSSAI to the UE when the AMF is going to perform the network slice-specific authentication and authorization for the S-NSSAI(s); or
• the partially allowed NSSAI to the UE after the network slice-specific authentication and authorization for the S-NSSAI(s) has been successfully performed; and
• otherwise, the AMF shall include the S-NSSAI(s) in the partially allowed NSSAI to the UE; or
• if the S-NSSAI(s) is rejected in the current TA but not all TAs of the registration area; and
• if the S-NSSAI is subject to NSAC for the maximum number of UEs, the AMF should include the S-NSSAI(s) in the partially rejected NSSAI to the UE;
• if the S-NSSAI(s) is subject to NSSAA, the AMF shall include the S-NSSAI(s) in:
• the partially rejected NSSAI to the UE when the AMF determines not to perform the network slice-specific authentication and authorization for the S-NSSAI(s);
• the pending NSSAI to the UE when the AMF is going to perform the network slice-specific authentication and authorization for the S-NSSAI(s); or

iii) either the partially allowed NSSAI or the partially rejected NSSAI to the UE after the network slice-specific authentication and authorization for the S-NSSAI(s) has been successfully performed;

NOTE 1: The AMF determines whether to perform the network slice-specific authentication and authorization procedure for the partial network slice based on its own local policy.

• if the S-NSSAI(s) is associated with a slice deregistration inactivity timer on the AMF side as specified in clause 4.6.2.9, the AMF shall include the S-NSSAI(s) in the partially rejected NSSAI to the UE; and
• otherwise, the AMF shall include the S-NSSAI(s) in either the partially allowed NSSAI or the partially rejected NSSAI to the UE; or
• if the partially allowed NSSAI, the partially rejected NSSAI, or both are changed, the AMF shall provide the new partially allowed NSSAI, the new partially rejected NSSAI, or both to the UE.

Upon receiving the partially allowed NSSAI, the UE shall regard the S-NSSAI(s) included in partially allowed NSSAI, if any, as the allowed S-NSSAI(s) for the current registration area and store the received partially allowed NSSAI as specified in clause 4.6.2.2.

Upon receiving the partially rejected NSSAI, the UE shall store the received partially rejected NSSAI as specified in clause 4.6.2.2. The UE shall not attempt to include the S-NSSAI, if any, in the requested NSSAI if the current TAI is in the list of TAs for which S-NSSAI is rejected.

The AMF shall ensure that there is also at least one S-NSSAI in the allowed NSSAI allocated to the UE as specified in clause 5.15.2.1 of 3GPP TS 23.501 [8].

The mobility management for partial network slice is only applicable to 3GPP access.

The mobility management for partial network slice is not applicable to a UE that is registering or registered for onboarding services in SNPN.