AMF CAG Information Management for 5G UE Registration
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Solution Overview
Problem
In 5G communication systems, User Equipment (UE) faces challenges in managing Closed Access Group (CAG) information, leading to unauthorized access and loss of CAG services due to synchronization issues between UE and network CAG information, resulting in disrupted services when UE attempts to register through non-CAG cells.
Innovation Solution
The method involves an Access and Mobility Management Function (AMF) that determines UE authorization and sends a registration reject message with a CAG information list, including a PLMN ID, allowed CAG list, and indication, allowing the UE to immediately select and camp on a CAG cell, ensuring access only through authorized CAG cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If UE attempts to register through non-CAG cells, then registration may be successful, but unauthorized access occurs and CAG service continuity is lost
Solution Approach 1:
The network performs preliminary authorization checks before allowing registration through non-CAG cells. The AMF determines whether the UE is authorized to access the network only through CAG cells based on stored CAG information, and rejects registrations from unauthorized UEs before they can establish connections through non-CAG cells, thereby preventing service disruption.
Solution Approach 2:
The system provides feedback to the UE about its CAG authorization status and required CAG information. When a UE attempts to register, the network responds with authorization decisions and, if necessary, provides CAG information lists that guide the UE to select appropriate CAG cells, ensuring future registrations maintain service continuity.
2Speed
If UE stores CAG information locally, then access speed improves, but synchronization issues cause unauthorized access and service disruption
Solution Approach 1:
The network maintains the authoritative CAG information and provides feedback to UEs during registration processes. When CAG information becomes outdated or incorrect in the UE, the network detects this during registration attempts and provides corrected CAG information lists, ensuring synchronization between network and UE CAG information while maintaining fast access.
Solution Approach 2:
The network performs preliminary validation of UE CAG information before allowing access. By checking whether the UE's stored CAG information matches the network's authorized list before permitting registration, the system prevents unauthorized access due to desynchronization while maintaining the speed benefits of local storage.
3Measurement precision
If network provides detailed CAG information to all UEs, then access accuracy improves, but signaling overhead and network load increase
Solution Approach 1:
The network provides CAG information selectively based on individual UE needs and authorization status. Instead of broadcasting detailed CAG information lists to all UEs, the network provides specific CAG information lists only to UEs that require them, determined by the UE's subscription profile and current registration context, thereby reducing overall signaling overhead while maintaining accurate authorization.
Solution Approach 2:
The network provides partial CAG information (specific CAG IDs in a list) rather than complete CAG configuration data to all UEs. This partial information approach provides sufficient guidance for UEs to select appropriate CAG cells without transmitting excessive detailed configuration data, balancing authorization accuracy with signaling efficiency.
Data Source
AI summary
Embodiments herein provide a method for managing CAG information. The method includes receiving, by an Access and Mobility Management Function (AMF), a registration request message from a User Equipment (UE) through a cell for registering to a network. Further, the method includes determining, by the AMF, that the UE is one of unauthorized to the cell when the cell is a CAG cell, and authorized to access the network only through a CAG cell when the cell is a non-CAG cell. Further, the method includes sending, by the AMF, a registration reject message to the UE, where the registration reject message includes a CAG information list.