NAS Connection Release on CAG Cells Using Validity-Based Control
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Solution Overview
Problem
Existing systems fail to efficiently manage NAS connection release for UEs accessing CAG/PNI-NPN networks, particularly when localized services are no longer valid or restricted, leading to unauthorized access and resource utilization.
Innovation Solution
Implement a method where the AMF adds validity or restriction information for CAG-IDs during NAS procedures and initiates NAS connection release when criteria are not met, while the UE receives and acts on validity information to locally release the connection upon timer expiry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the AMF maintains NAS connection for UEs accessing CAG/PNI-NPN networks, then network control and service delivery are ensured, but unauthorized access and resource utilization occur when localized services are no longer valid
Solution Approach 1:
The system implements feedback by continuously monitoring the validity status of localized services associated with CAG-IDs. When a service expires or becomes invalid, the network receives updated CAG configuration information indicating the change in validity, triggering appropriate NAS connection release actions to prevent unauthorized access while maintaining connections for valid services
Solution Approach 2:
The NAS connection management is made dynamic by transitioning from static connection maintenance to dynamic connection state changes. The system adapts connection status based on real-time service validity information, releasing connections when services expire and maintaining them when services remain valid, thereby preventing unauthorized access while ensuring reliable service delivery
2Object-affected harmful factors
If the network releases NAS connection when localized services expire, then unauthorized access is prevented, but connection release timing and coordination between network and UE must be precisely managed
Solution Approach 1:
The network performs preliminary action by proactively releasing the NAS connection at the network side when updated CAG configuration information indicates that localized services are no longer valid. This preliminary release prevents the UE from attempting unauthorized access, simplifying the overall coordination by eliminating the need for complex timer-based synchronization between network and UE
Solution Approach 2:
The invention extracts the connection release decision authority from the UE side and centralizes it at the network side (AMF). By having the AMF directly release the NAS connection based on received CAG configuration updates, the system eliminates the complexity of timer expiry coordination and ensures unified control over connection management
3Productivity
If the UE locally releases NAS connection upon timer expiry, then connection release is achieved, but precise timer synchronization and coordination with network release timing are required
Solution Approach 1:
The invention extracts the timer mechanism from the UE side and replaces it with direct network-controlled connection release. The AMF releases the NAS connection immediately upon receiving updated CAG configuration information indicating service expiration, eliminating the need for UE-side timers and their associated synchronization complexity while maintaining efficient connection release
Data Source
AI summary
In accordance with one novel aspect, a method of handling updated a CAG related configuration and in response perform a NAS procedure for releasing NAS connection is proposed. While camping on a CAG cell, during a NAS procedure, a UE receives a DL NAS message from AMF that carries validity or restriction information associated with a CAG-ID for the current PLMN and the CAG-ID is supported by the current CAG cell and included in the DL NAS message, and the validity or restriction criteria are not met according to the validity or restriction information. The UE starts a timer to allow the AMF to release the NAS connection. The UE locally releases the NAS connection upon timer expiry.