AMF Selection Consistency for Multi-SMF 5G Terminals
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Solution Overview
Problem
In 5G systems, when a terminal is served by multiple Session Management Function (SMF) network elements, ensuring that all SMFs select the same available Access and Mobility Management Function (AMF) network element to replace an unavailable one is challenging, leading to potential procedure conflicts.
Innovation Solution
A method where the second AMF network element, upon learning of the unavailability of the first AMF, obtains the terminal's context from a database, updates the context with its identifier and paging status, and sends a paging message to ensure it serves the terminal, even if initially different AMFs were selected by each SMF.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple SMF network elements independently re-select AMF network elements when the current AMF is unavailable, then service continuity can be maintained, but procedure conflicts occur due to different AMF selections
Solution Approach 1:
The patent introduces a database as an intermediary component that stores terminal context information including the selected AMF identifier. When an SMF needs to re-select an AMF, it queries this database to obtain the same AMF selection made by other SMFs serving the same terminal, ensuring consistent AMF selection across all SMFs without direct coordination between them.
Solution Approach 2:
The system implements feedback mechanisms where SMF network elements query the database to obtain information about AMF selections made by other SMFs. This feedback loop ensures that each SMF can independently make the same AMF selection by referencing the stored context information, thereby avoiding procedure conflicts while maintaining service continuity.
2Productivity
If SMF network elements select different available AMF network elements, then load distribution is improved, but terminal service consistency deteriorates due to procedure conflicts
Solution Approach 1:
The database acts as a mediator that stores the terminal's selected AMF identifier in its context information. All SMF network elements query this database to obtain the same AMF selection, ensuring that terminal service consistency is maintained while still allowing multiple SMFs to serve the terminal simultaneously with proper load distribution.
3Reliability
If a single AMF network element is selected to serve the terminal, then procedure conflicts are avoided, but system adaptability decreases when the AMF becomes unavailable
Solution Approach 1:
The system dynamically selects AMF network elements based on real-time availability. When the currently selected AMF becomes unavailable, the SMF queries the database to obtain updated AMF selection information and re-establishes connections accordingly. This dynamic adaptation ensures both procedure conflict avoidance and system resilience to AMF failures.
Data Source
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AI summary
Embodiments of the present invention disclose a session processing method and a related device. The method includes: upon learning, by a second AMF network element from a first SMF network element, that a first AMF network element serving a terminal is unavailable, obtaining, by the second AMF network element, a context of the terminal from a database, where the context of the terminal includes an identifier of the first SMF network element and an identifier of a second SMF network element; paging, by the second AMF network element, the terminal, and sending an identifier of the second AMF network element and a paging status indication to the database to update the context of the terminal; and receiving, by the second AMF network element, a service request message from the terminal, where the service request message is used for establishment of a user plane resource for a session of the terminal. When a terminal has a plurality of sessions associated with a plurality of SMFs, it can be ensured that a second AMF network element triggering paging finally serves the terminal, thereby avoiding a procedure conflict caused by a plurality of AMF network elements serving one terminal.