Xn Handover Authentication Synchronization in 5G PLMN Transitions
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Solution Overview
Problem
During an Xn handover from one serving PLMN to another, the UE and 5G core network may become out of sync, leading to authentication failures and service disruptions as the UE maintains the old PLMN while the core network retains the previous PLMN, causing a mismatch that prevents access to services.
Innovation Solution
A method is introduced to handle authentication procedures by performing a registration to a first PLMN, sending authentication messages with the PLMN identifier, and managing handovers by updating the Unified Data Management (UDM) with the new PLMN identifier, ensuring synchronization between the UE and the 5G core network during Xn handovers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If Xn handover procedure changes serving PLMN from first PLMN to second PLMN, then mobility and network flexibility are improved, but synchronization between UE and core network is lost causing authentication failures
Solution Approach 1:
The AMF initiates a new authentication procedure after detecting PLMN change through Xn handover. By performing preliminary authentication actions before service access, the system ensures that the UE and core network are synchronized on the new serving PLMN, preventing authentication failures while maintaining mobility flexibility
Solution Approach 2:
The system uses feedback from the Xn handover procedure to detect when serving PLMN changes occur. This feedback mechanism triggers the authentication refresh process, ensuring that the UE and core network maintain synchronization. The AMF monitors handover events and initiates authentication when PLMN change is detected, resolving the contradiction between mobility and authentication reliability
2Reliability
If authentication procedure is initiated during Xn handover, then security is maintained, but service continuity is interrupted due to authentication failures
Solution Approach 1:
The authentication procedure is made dynamic by conditionally initiating it only when PLMN change is detected through Xn handover feedback. Rather than statically requiring authentication in all cases or none, the system adapts the authentication timing based on actual network conditions, maintaining security when necessary while minimizing service interruption
Solution Approach 2:
By initiating authentication promptly after detecting PLMN change, the system performs the security procedure as a preliminary action before service access is attempted. This timing strategy ensures security is established while the service interruption window is minimized, as authentication completes before the UE attempts to access services with the new PLMN context
Data Source
AI summary
This disclosure defines a procedure to handle authentication procedure during Xn handover. More specifically it defines handling of an authentication procedure when Xn handover takes place from one serving PLMN to another serving PLMN during the authentication procedure.