Pending NSSAI Signaling for AMF Re-Allocation in 5G Slice Authentication
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Solution Overview
Problem
The current 3GPP specifications are unclear regarding the Network Slice-Specific Authentication and Authorization (NSSAA) procedure, leading to situations where newly added S-NSSAIs in the Allowed NSSAI are not supported by the newly selected AMF, resulting in service degradation for services using these network slices in the 5G System (5GS).
Innovation Solution
The method involves sending and receiving Pending Network Slice Selection Assistance Information (NSSAI) during the Access and Mobility Management Function (AMF) re-allocation procedure, ensuring that the AMF Set or list of candidate AMFs can support all S-NSSAIs, including those in the Pending NSSAI, by including Pending NSSAI in the Nnssf_NSSelection_Get message to the Network Slice Selection Function (NSSF).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the UE does not include Pending NSSAI in Requested NSSAI during Registration procedure while NSSAA is ongoing, then the Registration procedure can be initiated, but the newly selected AMF cannot serve the newly added S-NSSAIs after NSSAA completion
Solution Approach 1:
The patent applies preliminary action by including the Pending NSSAI in the Requested NSSAI during the Registration procedure while NSSAA is ongoing. This ensures that the NSSF is aware of the pending S-NSSAIs in advance, so that when the AMF re-allocation occurs and a new AMF is selected, that AMF is properly configured to handle all S-NSSAIs including those that will be added after NSSAA completion, thus preventing service degradation.
2Productivity
If the NSSF selects AMF Set or candidate AMFs based on Requested NSSAI without Pending NSSAI, then the AMF re-allocation can be performed, but the newly selected AMF cannot handle the newly added S-NSSAIs
Solution Approach 1:
The patent applies preliminary action by ensuring that the Pending NSSAI is included in the Requested NSSAI before the NSSF performs AMF selection. This allows the NSSF to pre-select an AMF that is capable of handling all required S-NSSAIs, including those pending NSSAA approval, thereby ensuring the selected AMF has the necessary adaptability and versatility to serve all network slices without requiring re-allocation after NSSAA completion.
Solution Approach 2:
The patent uses the Requested NSSAI as an intermediary that carries information about Pending NSSAI from the UE to the NSSF. This intermediary mechanism ensures that the NSSF receives complete information about all S-NSSAIs that need to be supported, enabling it to make an informed AMF selection that balances both re-allocation efficiency and slice support capability.
3Device complexity
If the Requested NSSAI does not include Pending NSSAI, then the NSSF can process the registration request, but service degradation occurs for services using newly added S-NSSAIs
Solution Approach 1:
The patent applies preliminary action by including Pending NSSAI in Requested NSSAI before NSSF processing. This ensures that the NSSF has complete information upfront about all S-NSSAIs that need to be supported, allowing it to select an appropriate AMF in a single operation without requiring additional processing or re-allocation later, thus maintaining both low complexity and high service availability.
Solution Approach 2:
The patent implements feedback by ensuring that the Pending NSSAI information flows back to the NSSF through the Requested NSSAI parameter. This feedback loop allows the NSSF to make an informed decision about AMF selection that accounts for future S-NSSAI additions, preventing service degradation while maintaining processing efficiency.
Data Source
AI summary
In the current 3GPP specifications, there are some unclear situations regarding the NSSAA procedure.An aspect of this disclosure includes a method of a first communication apparatus. The method includes communicating with a second communication apparatus. The method includes sending Requested Network Slice Selection Assistance Information (NSSAI) to the second communication apparatus in a case where the first communication apparatus has Pending NSSAI. The Requested NSSAI includes the Pending NSSAI.