VoNR Cell Whitelist Filtering for IMS Voice Reliability
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Solution Overview
Problem
IMS voice session failures occur due to inappropriate inter-RAT redirection between 4G and 5G networks during EPS fallback procedures, leading to reduced user experience and increased signaling overhead, especially when NR cells do not support VoNR.
Innovation Solution
A UE generates and maintains a whitelist of NR cells that support VoNR, pruning non-supporting cells from measurement reports to prevent unnecessary redirections during IMS voice session establishment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE includes all measured NR cells in measurement reports during EPS fallback, then the handover decision is based on complete information, but IMS voice session failures occur when redirected to NR cells that do not support VoNR
Solution Approach 1:
The UE performs preliminary actions by maintaining a whitelist of NR cells that support VoNR before the handover decision is made. This whitelist is updated based on previous measurements and VoNR capability detections, allowing the UE to proactively identify suitable target cells and avoid redirecting to cells that cannot support voice sessions, thereby preventing voice session failures before they occur.
Solution Approach 2:
The whitelist of VoNR-capable NR cells acts as an intermediary mechanism between the measurement report generation and the handover decision. By filtering measurement reports to include only cells from the whitelist, the system ensures that handover decisions are made based on cells known to support VoNR, thus preventing the harmful effect of redirecting to incompatible cells while still utilizing measurement information.
2Stability of the object's composition
If the UE filters measurement reports to include only VoNR-capable NR cells, then voice session continuity is maintained, but the handover decision may miss potentially suitable non-whitelisted cells
Solution Approach 1:
The system performs preliminary actions by continuously updating the whitelist of VoNR-capable cells based on measurements and capability detections. This ensures that the whitelist remains current and adaptable, allowing the filtered measurement report approach to maintain both voice session continuity and handover flexibility, as new VoNR-capable cells are added to the whitelist over time.
Solution Approach 2:
The system implements feedback mechanisms where the UE monitors VoNR capability of NR cells and updates the whitelist accordingly. This feedback loop ensures that the filtering of measurement reports remains adaptive, maintaining voice session continuity while preserving handover flexibility as the network evolves and new VoNR-capable cells become available.
3Reliability
If the UE performs EPS fallback procedure for cells without VoNR support, then voice sessions can be established on 4G network, but signaling overhead increases and user experience degrades
Solution Approach 1:
The UE performs preliminary actions by maintaining and utilizing the whitelist of VoNR-capable cells before initiating handover procedures. By filtering measurement reports to include only whitelisted cells, the UE ensures that handovers are directed to cells that can support voice sessions natively, thereby avoiding the need for EPS fallback procedures and reducing signaling overhead associated with fallback operations.
Data Source
AI summary
An apparatus for wireless communication of a UE is disclosed. The apparatus may initiate, at a new radio (NR) serving cell, a voice session with an IMS. The apparatus may perform, in response to determining that voice over NR (VoNR) is not supported by the first NR cell, an EPS fallback procedure to establish the voice session with the IMS. The apparatus may update a whitelist of NR cells that support VoNR to include the first NR cell when it is determined that the first NR cell supports VoNR.