UE Registration Across PLMNs Using Separate NAS Security Contexts
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Solution Overview
Problem
Existing user equipment (UE) devices face security and registration issues due to the inability of Universal Subscriber Identity Modules (USIM) to store multiple Non-Access Stratum (NAS) security contexts for different Public Land Mobile Networks (PLMNs), leading to potential overwrites and mix-ups of NAS COUNT values.
Innovation Solution
The ME component of the UE determines the USIM's capability to store multiple NAS security contexts and, if unsupported, stores these contexts in its non-volatile memory, ensuring separate storage for each PLMN, thereby preventing NAS COUNT value overwrites.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the USIM stores multiple NAS security contexts for different PLMNs, then the UE can maintain security contexts for multiple networks, but the USIM storage capacity is exceeded causing overwrites and mix-ups of NAS COUNT values
Solution Approach 1:
The patent segments the storage of NAS security contexts by separating them into individual files within the USIM, each file containing a complete NAS security context for a specific PLMN. This segmentation prevents overwrites and mix-ups by ensuring each context is stored in an isolated, dedicated space with its own identifier (PLMN ID), thus resolving the contradiction between supporting multiple PLMNs and maintaining data integrity.
2Device complexity
If the USIM stores only a single NAS security context, then the storage structure remains simple, but the UE cannot properly register to multiple different PLMNs simultaneously
Solution Approach 1:
The patent implements a universal file structure in the USIM that can accommodate multiple NAS security contexts, each associated with a different PLMN. The system uses a standardized file format with PLMN-specific identifiers, allowing the USIM to function as a multi-context storage device while maintaining a consistent, manageable structure. This enables the UE to register to multiple PLMNs without significantly increasing overall system complexity.
3Reliability
If the UE stores multiple NAS security contexts in non-volatile memory, then NAS COUNT value integrity is preserved, but the device requires additional storage capacity beyond the USIM
Solution Approach 1:
The patent utilizes the hierarchical storage architecture by implementing a two-layer storage system: the USIM layer for persistent security context storage with organized file structures, and the device non-volatile memory layer for additional context storage when needed. This dimensional approach to storage allows the system to maintain reliability through proper separation of contexts while efficiently managing total storage requirements by leveraging existing hardware resources in a structured manner.
Data Source
AI summary
A user equipment (“UE”) can handle registrations of the UE in different wireless communication networks. The UE can obtain information indicating whether a Universal Subscriber Identity Module (“USIM”) of the UE supports storing multiple different Non-Access Stratum (“NAS”) security contexts of the UE associated with the different wireless communication networks. The UE can further determine whether the USIM supports storing the multiple different NAS security contexts of the UE associated with the different wireless communication networks based on the obtained information.