NAS Count Management for Multi-PLMN Wireless Reconnection
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Solution Overview
Problem
In 5G new radio wireless communications, user equipment (UE) faces challenges in managing multiple connections to different public land mobile networks (PLMNs) due to limitations in storing and managing non-access stratum (NAS) counts, leading to failed reconnections when switching between 3GPP and non-3GPP connections.
Innovation Solution
The UE is configured to establish and manage multiple NAS count pairs for different PLMNs, including deregistering inactive connections, receiving and verifying NAS count pairs from the access and mobility management function (AMF), and storing multiple security contexts to ensure valid security contexts during reconnection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE stores multiple NAS count pairs for different PLMNs, then the reliability of connection reestablishment is improved, but the device complexity increases
Solution Approach 1:
The patent segments the NAS count management by separating NAS count pairs into different storage locations based on PLMN type. 3GPP PLMN NAS count pairs are stored in a first storage location, while non-3GPP PLMN NAS count pairs are stored in a second storage location. This segmentation allows the UE to manage multiple NAS count pairs without confusion and ensures reliable reconnection to the correct PLMN while maintaining clear organizational structure.
Solution Approach 2:
The patent introduces an intermediary mechanism where the UE determines whether to reuse an existing NAS count pair or generate a new one based on PLMN identification. The AMF (Access and Mobility Management Function) acts as an intermediary that provides instructions on NAS count pair handling, mediating between the UE's connection requests and the network's security requirements.
2Reliability
If the UE deregisters inactive connections to reset NAS count pairs, then the reliability of security contexts is improved, but the loss of time increases
Solution Approach 1:
The patent applies preliminary action by having the UE deregister inactive connections and reset NAS count pairs before establishing new active connections. This preliminary deregistration ensures that the NAS count pairs being used are current and valid, preventing security context mismatches during connection reestablishment while maintaining efficient connection management.
Solution Approach 2:
The patent implements feedback mechanisms where the UE receives instructions from the AMF regarding NAS count pair handling. The AMF provides feedback on whether to reuse existing NAS count pairs or generate new ones, allowing the UE to adjust its behavior accordingly and minimize unnecessary deregistration operations that would consume time.
3Ease of operation
If the UE uses the same security context for multiple connections, then the ease of operation is improved, but the reliability of encryption decreases
Solution Approach 1:
The patent applies local quality by maintaining separate NAS count pairs for different PLMNs even though the same security context is used. Each PLMN has its own NAS count pair stored in appropriate storage locations, allowing the UE to manage multiple connections with a unified security context while maintaining PLMN-specific encryption tracking. This ensures reliable encryption for each connection without complicating the overall security context management.
Data Source
AI summary
A user equipment (UE) establishes a first type of connection to a first public land mobile network (PLMN), the first type of connection having a first non-access stratum (NAS) Count pair corresponding to a first NAS security context associated with the first PLMN, establishes a second type of connection to a second PLMN, wherein a previous second type of connection was established with the first PLMN, wherein the previous second type of connection has a second NAS Count pair corresponding to the first NAS security context, wherein the second type of connection has a third NAS Count pair corresponding to a second NAS security context associated with the second PLMN and deregisters the previous second type of connection with the first PLMN to reset the second NAS count pair at the first PLMN.