UE Interworking Without N26 Interface Support
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Solution Overview
Problem
Current protocols for UE registration to 3GPP and non-3GPP access networks may lead to incorrect behavior when handling indications of interworking without N26 interface support, especially when these indications are received over non-3GPP access.
Innovation Solution
A method where a UE ignores the indication of interworking without N26 interface support received over non-3GPP access and considers the N26 interface as supported for interworking, thereby triggering a TAU procedure after intersystem change from 5G to 4G.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the UE considers the second configuration (received over non-3GPP access) in the first network, then the UE can operate with multiple access types, but the UE behavior becomes incorrect due to conflicting interworking indications
Solution Approach 1:
The patent applies local quality by making the UE treat indications received over different access types differently. Specifically, the UE ignores the interworking indication received over non-3GPP access (second access type) while maintaining the indication received over 3GPP access (first access type). This differential treatment resolves the conflict by applying quality differentiation to the information processing based on the access type source.
2Stability of the object's composition
If the UE uses the indication from non-3GPP access, then the configuration can be unified across accesses, but the interworking procedure becomes incorrect
Solution Approach 1:
The patent applies local quality by making the UE treat indications received over different access types differently. Specifically, the UE ignores the interworking indication received over non-3GPP access (second access type) while maintaining the indication received over 3GPP access (first access type). This differential treatment resolves the conflict by applying quality differentiation to the information processing based on the access type source.
3Reliability
If the UE triggers TAU procedure after intersystem change, then the interworking can be handled correctly, but the procedure complexity increases
Solution Approach 1:
The patent applies inversion by changing the UE's decision logic regarding which indication to trust. Instead of following the conventional approach of using the most recent or any received indication, the UE inverts the logic by explicitly ignoring indications from non-3GPP access and prioritizing indications from 3GPP access. This inverted approach simplifies the decision-making process while ensuring correct interworking behavior.
Data Source
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AI summary
A method of performing intersystem change without N26 interface supported or not supported when a UE is registered to the same or different networks over 3GPP and non-3GPP accesses is proposed. UE registers to one or more PLMN/SNPN over 3GPP access (411) and non-3GPP access (421). UE receives a REGISTRATION ACCEPT message over 3GPP access (412), which carries a first 5GS network feature support IE, which indicates that interworking without N26 interface not supported. UE also receives a REGISTRATION ACCEPT message over non-3GPP access (422), which carries a second 5GS network feature support IE, which indicates that interworking without N26 interface supported. UE ignores the second indication received over non-3GPP access and considers that N26 interface is supported for interworking (441). As a result, after intersystem change from 5G to 4G, UE triggers a TAU procedure over LTE in 4G EPS (451).