PDU Session Re-Anchoring Using SMF Re-Selection Context
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Solution Overview
Problem
Existing approaches for re-anchoring PDU Session Anchors (PSAs) in Edge Computing (EC) scenarios lack sufficient information for SMF re-selection, particularly in cases where the new SMF needs to control UPFs with N6 access to DNs at requested locations, such as in campus scenarios or when UE mobility exceeds SMF service areas.
Innovation Solution
The proposed method involves the SMF conveying EC dynamic context information to the AMF, which includes DNAIs, traffic filters, N6 routing, DNS configuration, and local policies, enabling the AMF to select and configure a new SMF for re-establishing the UE PDU session with the appropriate PSA.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the SMF conveys EC dynamic context information to the AMF for SMF re-selection, then the applicability of EC-related EAS selection and re-selection use cases is extended, but the device complexity and information management overhead increase
Solution Approach 1:
The patent applies preliminary action by having the first SMF convey EC dynamic context information to the AMF before the actual SMF re-selection occurs. This allows the AMF to have the necessary information ready when selecting a new SMF, enabling seamless re-anchoring without service interruption. The context information including DNAIs, traffic filters, and N6 routing is prepared in advance, resolving the contradiction by extending adaptability while managing complexity through proactive information sharing.
Solution Approach 2:
The AMF acts as an intermediary between the first SMF and the second SMF during the re-selection process. It receives EC dynamic context information from the first SMF, selects the appropriate second SMF based on this information, and conveys it to the new SMF. This intermediary role extends the applicability of EC use cases while distributing the complexity across multiple network functions rather than concentrating it in a single entity.
2Reliability
If PSA relocation is performed with SMF re-selection, then seamless traffic routing is enabled in campus scenarios and when UE mobility exceeds SMF service areas, but the loss of time for session re-establishment increases
Solution Approach 1:
The patent reduces re-establishment time by having the first SMF convey EC dynamic context information to the AMF in advance. When SMF re-selection is triggered, the AMF already possesses the necessary context including DNAIs, traffic filters, and N6 routing information, allowing the second SMF to quickly establish the new PDU session without requiring extensive information gathering, thus maintaining seamless traffic routing while minimizing time loss.
Solution Approach 2:
The mechanism establishes a feedback loop where the AMF receives EC dynamic context information from the first SMF and uses it to select and configure the second SMF. This feedback of contextual information accelerates the re-establishment process by eliminating the need for the new SMF to request and wait for this information, thereby reducing time loss while ensuring reliable seamless traffic routing.
3Adaptability or versatility
If the AMF selects a new SMF based on EC dynamic context information, then PSA relocation with new SMF control is enabled, but the quantity of information to be managed and transmitted increases
Solution Approach 1:
The patent segments the information management task by dividing the EC dynamic context information into specific components (DNAIs, traffic filters, N6 routing information) and transmitting only the necessary segments from the first SMF to the AMF and then to the second SMF. This segmentation enables PSA relocation with new SMF control while managing the quantity of information by transmitting only relevant data rather than complete session contexts.
Solution Approach 2:
The mechanism extracts and transmits only the essential EC dynamic context information (DNAIs, traffic filters, N6 routing) needed for PSA relocation and new SMF selection, rather than transmitting complete session information. This extraction approach enables the AMF to select a new SMF based on critical information while minimizing the quantity of data to be managed and transmitted across the network.
Data Source
AI summary
Re-anchoring with Session Management Function (SMF) re-selection is disclosed herein. According to some embodiments, if, for an existing User Equipment (UE) Packet Data Unit (PDU) session, an SMF determines that the current PDU Session Anchor (PSA) for the UE PDU Session is to be relocated and further determines that relocation involves an SMF re-selection, then the SMF initiates re-establishment of the PDU session. During re-establishment, the SMF conveys to an Access and Mobility Management Function (AMF) Edge Computing (EC) context information relevant for the new PDU session. The AMF in some embodiments may use some of this information related to the location of the PSA (DNAI) to select the new SMF, and passes this information to the selected SMF for the new PDU session. Based on the information received, the new SMF in some embodiments establishes the new PDU session and selects and configures the PSA(s) for the new session.