CAG Configuration Update via Downlink NAS for 5G Access Control
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Solution Overview
Problem
Current wireless mobile communication networks face challenges in providing localized services efficiently, as users need to discover, select, and access Non-Public Networks (NPNs) while ensuring access control and validity criteria are met, particularly with the use of Closed Access Groups (CAGs) in 5G systems.
Innovation Solution
A method is proposed where user equipment (UE) receives updated CAG-related configurations via DL NAS messages, determining supported CAG-IDs, validity information, and access permissions, leading to either entering a LIMITED-SERVICE state or a PLMN-SEARCH state based on these criteria, ensuring compliant access to 5G networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If UE automatically selects and accesses CAG cells without updated configuration checks, then access speed is improved, but network security and access control reliability deteriorate
Solution Approach 1:
The network performs preliminary actions by sending updated CAG configuration information to the UE before the UE attempts to access CAG cells. The UE stores this configuration and uses it to determine whether to allow access to specific CAG cells, preventing unauthorized access attempts before they occur.
Solution Approach 2:
The system implements feedback mechanisms where the network monitors UE access patterns and sends updated CAG configuration information when changes are detected. This feedback loop ensures that the UE has current access control information while maintaining secure access procedures.
2Reliability
If UE checks all validity criteria and compares CAG-IDs before accessing CAG cells, then access control reliability is improved, but processing time and complexity increase
Solution Approach 1:
The UE performs preliminary processing by storing CAG configuration information received from the network, including lists of allowed CAG-IDs and validity criteria. This pre-stored information is readily available when access decisions are needed, eliminating the need for real-time configuration retrieval and reducing access processing time.
Solution Approach 2:
The access control process is segmented into distinct phases: configuration reception and storage, validity criteria evaluation, and access decision-making. By dividing the process into manageable segments with pre-computed components, the system reduces the computational burden during actual access attempts.
3Stability of the object's composition
If UE enters LIMITED-SERVICE state and searches for suitable cells, then service continuity is improved, but network search time increases
Solution Approach 1:
The network performs preliminary actions by identifying and recommending suitable CAG cells to the UE before the UE needs to access services. The UE stores this pre-identified cell information, which can be quickly retrieved when entering LIMITED-SERVICE state, reducing the time required to find suitable cells while maintaining service continuity.
Data Source
AI summary
A method of handling updated CAG related configuration is proposed. UE receives an updated CAG related configuration in a DL NAS message via a CAG cell, which broadcasts a list of supported CAG-IDs of the current network. UE may also receive an updated CAG related configuration in a DL NAS message via a non-CAG cell of the current network. The UE examines the list of allowed CAG-IDs in the updated CAG related configuration, determines whether they are supported by the CAG cell, whether they are associated with validity information, whether the validity criteria are met, whether the UE is ONLY allowed to access 5GS via CAG cells, and whether the UE has any emergency PDU session. Depending on the determination, the UE then either enters LIMITED-SERVICE and search for suitable cell in the current network, or enters PLMN-SEARCH state and applies PLMN selection process.