AMF IMS Voice Indication for 5G Call Setup Reliability
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Solution Overview
Problem
There is a need for improved handling of voice services in a 5G system (5GS) to prevent call setup termination issues, particularly when a User Equipment (UE) moves between areas with different voice support capabilities, such as EPS Fallback and VoNR, leading to incompatible capabilities and potential call failures.
Innovation Solution
The implementation of an Access and Mobility Management Function (AMF) and Unified Data Manager (UDM) that provide an indication of IMS voice support over Packet Switched (PS) services to the radio access network, allowing the network to manage voice services efficiently by determining whether to use EPS Fallback or VoNR based on the UE's capabilities and roaming agreements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the network uses EPS fallback for voice services in 5GS, then compatibility with UEs lacking VoNR support is improved, but call setup termination issues occur when UEs move between areas with different voice support capabilities
Solution Approach 1:
The network performs preliminary assessment of UE voice capabilities during initial registration or session establishment, determining whether the UE supports VoNR or requires EPS fallback before actual voice service deployment. This advance determination prevents call setup termination issues by ensuring the appropriate voice service mode is selected before the UE moves to areas with different capabilities.
Solution Approach 2:
The system implements feedback mechanisms where the network continuously monitors UE mobility status and current area voice support capabilities. When a UE moves between areas with different voice service support (VoNR vs EPS fallback), the network receives feedback about the new area's capabilities and adjusts the voice service mode accordingly, preventing call termination by adapting to changing conditions.
2Measurement precision
If the network provides detailed IMS voice support indications to all UEs, then voice service handling accuracy is improved, but network signaling overhead and complexity increase
Solution Approach 1:
Instead of providing uniform detailed IMS voice support indications to all UEs, the network applies differentiated indication strategies based on local conditions - specifically, whether the UE is in an area with VoNR support or requires EPS fallback. The network provides precise voice capability indications only where necessary, reducing overall signaling complexity while maintaining accuracy for each UE's specific context.
Solution Approach 2:
The system dynamically changes the level of detail in voice support indications based on UE capabilities and current network conditions. For UEs with confirmed VoNR support in supported areas, simplified indications are used. For UEs requiring EPS fallback or in areas with limited support, more detailed indications are provided. This parameter adaptation reduces overall network signaling complexity while maintaining necessary precision.
Data Source
AI summary
There is provided mechanisms for indicating IMS voice support over PS for a UE in a PLMN. A method is performed by an AMF of the PLMN. The method comprises obtaining a trigger for the AMF to indicate IMS voice support over PS for the UE in the PLMN. The method comprises obtaining information of IMS voice support over PS for the UE in the PLMN. The method comprises providing, based on the information, an indication to a radio access network serving the UE in the PLMN. The indication specifies the IMS voice support over PS for the UE in the PLMN.