PDU Session Re-Anchoring with SMF Re-Selection for Edge Computing
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Solution Overview
Problem
Existing methods for re-anchoring PDU Sessions in Edge Computing (EC) fail to provide sufficient information for Session Management Function (SMF) re-selection, especially when a new User Equipment (UE) location is outside the SMF's service area or when a Domain Name System (DNS)-triggered or Application Function (AF)-requested Data Network Access Identifier (DNAI) requires a distributed anchor.
Innovation Solution
The proposed method involves a first SMF initiating re-establishment of a UE PDU session by conveying Edge Computing (EC) dynamic context information to an Access and Mobility Management Function (AMF), which selects a second SMF based on the EC dynamic context information, including DNAI, traffic filters, N6 routing, DNS configuration, and local policies, enabling the new SMF to establish and configure the new PDU Session Anchor (PSA).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If re-anchoring is performed without conveying EC dynamic context information to AMF, then the procedure is simpler, but the SMF cannot be properly re-selected when UE location changes or DNAI requires distributed anchor
Solution Approach 1:
The first SMF performs preliminary actions by determining EC dynamic context information (including DNAI, traffic filters, N6 routing, DNS configuration, and local policies) before initiating PDU session re-establishment. This information is conveyed to the AMF in advance, enabling the AMF to pre-identify a suitable second SMF based on the DNAI and other context parameters, thus ensuring reliable SMF re-selection before the actual handover occurs.
Solution Approach 2:
The AMF acts as an intermediary between the first SMF and the second SMF. It receives the EC dynamic context information from the first SMF, uses this information to select an appropriate second SMF based on DNAI and other criteria, and then conveys the information to the selected second SMF. This intermediary role simplifies the overall procedure by centralizing the selection logic in the AMF while maintaining reliability through informed SMF re-selection.
2Measurement precision
If EC dynamic context information is conveyed to AMF for SMF re-selection, then SMF re-selection accuracy improves, but information transmission overhead increases
Solution Approach 1:
The solution extracts only the essential EC dynamic context information needed for SMF re-selection (DNAI, traffic filters, N6 routing, DNS configuration, and local policies) from the complete set of possible session parameters. By taking out only the critical elements required for accurate SMF selection, the information transmission overhead is minimized while maintaining sufficient precision for reliable SMF re-selection based on UE location and DNAI requirements.
3Reliability
If SMF re-allocation is performed for re-anchoring, then service continuity is maintained during UE mobility, but session re-establishment complexity increases
Solution Approach 1:
The first SMF performs preliminary actions by determining EC dynamic context information and identifying the need for SMF re-allocation before initiating PDU session re-establishment. This advance preparation ensures that service continuity is maintained, as the second SMF is already identified and configured with necessary context information before the actual session transition occurs, reducing the complexity of the re-establishment process.
Solution Approach 2:
The AMF serves as an intermediary that manages the session re-establishment process. It receives EC dynamic context information from the first SMF, selects the appropriate second SMF, and coordinates the session transition. This intermediary management simplifies the overall re-establishment complexity by centralizing coordination tasks while ensuring service continuity through proper SMF re-allocation during UE mobility or DNAI changes.
Data Source
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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.