AMF Handover Profile Retrieval Without Repeated UDM Messaging
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Solution Overview
Problem
The increased frequency of handovers between 4G and 5G networks results in excessive signaling to the unified data management node (UDM) and unified data repository (UDR), leading to inefficiencies and potential loss of information due to repeated registration and subscription messages.
Innovation Solution
An access and mobility management function (AMF) obtains subscriber profile information directly from an unstructured data storage function (UDSF) or from the old AMF during handovers, eliminating the need for get and subscribe messages to the UDM, thereby optimizing signaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If the AMF sends get messages and subscribe messages to the UDM during handovers, then the subscriber profile information can be retrieved and updated, but the signaling load between network nodes increases significantly
Solution Approach 1:
The AMF retrieves subscriber profile information in advance during initial registration or previous handovers, storing it locally before it is needed. This preliminary retrieval eliminates the need to send get messages to the UDM during subsequent handovers, reducing signaling load while ensuring information availability when required
Solution Approach 2:
The AMF creates and maintains a local copy of the subscriber profile information received from the UDM. This copy allows the AMF to operate independently during handovers without continuously querying the UDM, thereby reducing the quantity of signaling messages while maintaining access to necessary subscriber data
2Reliability
If the AMF subscribes to notifications from the UDM for subscriber profile changes, then the AMF can receive real-time updates, but the signaling overhead increases during frequent handovers
Solution Approach 1:
The AMF establishes the subscription relationship with the UDM during initial registration or setup phase, before frequent handovers occur. This preliminary subscription ensures the AMF is registered to receive notifications when changes occur, while avoiding the need to re-establish subscriptions during each handover event
Solution Approach 2:
Once the AMF subscribes to notifications from the UDM, this subscription relationship continues across handover events. The UDM maintains the notification subscription active, allowing the AMF to receive change notifications without needing to resend subscription requests, thereby maintaining reliability while reducing repetitive signaling
3Measurement precision
If the AMF retrieves subscriber profile information during each handover, then the information is current and accurate, but the handover process becomes slower and more resource-intensive
Solution Approach 1:
The AMF retrieves and caches subscriber profile information in advance, before handover events occur. This cached information is readily available during handovers, eliminating the time delay associated with real-time retrieval from the UDM while maintaining sufficient accuracy for handover operations
Solution Approach 2:
The AMF maintains a local copy of the subscriber profile information that can be quickly accessed during handovers. This local copy enables rapid handover execution without the time penalty of network round-trips to the UDM, while the copy is kept sufficiently current for operational needs
4Adaptability or versatility
If the system uses traditional signaling protocols for AMF-UDM communication during handovers, then compatibility with existing networks is maintained, but the signaling complexity and message repetition increase
Solution Approach 1:
The communication process is segmented into distinct phases: initial information retrieval phase where the AMF obtains subscriber profile from the UDM, and handover execution phase where the AMF uses cached information. This segmentation allows the use of standard protocols during initial setup while simplifying handover operations by reducing protocol exchanges
Solution Approach 2:
The essential subscriber profile information is extracted and cached locally in the AMF during initial registration. This extraction eliminates the need for repeated protocol exchanges during handovers, reducing signaling complexity while maintaining compatibility with existing UDM interfaces for initial data retrieval
Data Source
AI summary
An access and mobility management function (AMF) configured to obtain subscriber profile information without sending a get message and a subscribe message to a unified data management node (UDM) is described herein. The AMF is a new AMF that receives a registration request as part of a handover from an old AMF and receives user equipment (UE) context information from the old AMF. Without sending a get message to the UDM, the AMF obtains subscriber profile information by either fetching the subscriber profile information from an unstructured data storage function (UDSF) shared by a pool of AMFs, when the UDSF is available, or receiving the subscriber profile information from old AMF, when the UDSF is not available. Also, without sending a subscribe message to the UDM, the AMF receives notification of changes to the subscriber profile information from the UDM.