UE IMS Registration for EPS Voice Services
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Solution Overview
Problem
In evolved packet system (EPS) mobile communication systems, there is a lack of guaranteed IMS registration and successful IMS registration for voice services, leading to potential failures in initiating and maintaining IMS voice sessions, especially when the UE's voice setting is set to 'IMS PS voice only' or 'IMS voice preferred, CS voice secondary', and the network indicates 'IMS Voice over PS session supported'. Additionally, UEs may be constrained in inappropriate radio access technologies (RATs) and face challenges in reverting usage settings after temporary changes.
Innovation Solution
The solution involves ensuring IMS registration is triggered with proper indicators when the UE's voice setting is 'IMS PS voice only' or 'IMS voice preferred, CS voice secondary', and the network supports IMS voice over PS sessions. If IMS registration fails, the UE attempts combined registration procedures for CSFB or retries IMS registration. The UE also monitors for VoIMS indicators to switch to supportive RATs and reverts usage settings to ensure voice services are available when needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE's voice setting is set to 'IMS PS voice only' or 'IMS voice preferred, CS voice secondary' and the network indicates 'IMS Voice over PS session supported', then the UE should be able to use IMS voice services, but IMS registration may fail and voice services are not guaranteed
Solution Approach 1:
The patent applies preliminary action by triggering IMS registration in advance when specific conditions are met (UE voice setting is 'IMS PS voice only' or 'IMS voice preferred, CS voice secondary' and network indicates 'IMS Voice over PS session supported'). This proactive registration attempt ensures voice services are available before needed, rather than waiting for failure to occur.
Solution Approach 2:
The patent implements feedback mechanisms by monitoring IMS registration status and VoIMS indicators. When registration fails or conditions change, the system receives feedback and automatically retries registration or switches to combined registration procedures, ensuring reliable voice service availability through continuous status monitoring and adaptive response.
2Reliability
If the UE attempts combined registration procedures for CSFB when IMS registration fails, then voice service availability is improved, but the complexity of registration procedures increases
Solution Approach 1:
The patent applies dynamics by implementing adaptive registration procedures that change based on real-time conditions. The UE dynamically switches between IMS-only registration and combined registration procedures depending on IMS registration success, network indicators, and UE voice settings. This dynamic adaptation ensures voice service availability while managing complexity through conditional logic rather than always using the most complex procedure.
3Reliability
If the UE is constrained in inappropriate radio access technologies (RATs), then the UE may lose access to voice services, but switching RATs increases system complexity
Solution Approach 1:
The patent implements feedback by continuously monitoring VoIMS indicators from the network and UE usage settings. When the UE detects it is constrained in an inappropriate RAT (e.g., data-centric mode when voice is needed, or inappropriate CS/PS preference), it receives feedback about the mismatch and automatically switches to an appropriate RAT configuration to restore voice service accessibility.
4Reliability
If the UE does not guarantee IMS registration, then the system simplicity is maintained, but voice service failures occur
Solution Approach 1:
The patent applies preliminary action by proactively triggering IMS registration when conditions indicate voice services will be needed (based on UE voice settings and network VoIMS indicators). This ensures registration is completed before voice services are required, preventing service failures without requiring complex continuous registration management.
Solution Approach 2:
The patent implements self-service by enabling the UE to autonomously determine when IMS registration is needed based on its own voice settings and received network indicators. The UE independently triggers registration procedures without requiring complex network-controlled registration management, simplifying overall system complexity while ensuring voice service reliability.
Data Source
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Figure 2A
AI summary
A method in a User Equipment, UE, with a voice setting determined by a first indicator related to voice services in an Evolved Packet System, EPS.is disclosed. The method comprises receiving a Non Access Stratum, NAS, protocol Accept message with a second indicator indicating that an IMS voice over packet-switched, PS, session is supported; and responsive to the first indicator or the second indicator, determining availability of voice services over IP Multimedia Subsystem IMS.