UE Measurement Reporting to Prevent VoLTE-to-5G Call Drops
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Solution Overview
Problem
5G user equipment (UE) experiences call drops and mobile originated/terminated call setup failures when moving from LTE to 5G SA networks due to unsupported voice over new radio (VoNR), with existing technologies lacking predefined handling to avoid handovers to non-supporting cells.
Innovation Solution
The UE delays sending measurement reports for specific events (B1 and B2) until an ongoing VoLTE call is completed, and sends them only if both the UE and the 5G network support VoNR, or performs handovers after call disconnection if VoNR is not supported, ensuring uninterrupted service.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the UE sends measurement reports immediately for 5G cells during an ongoing VoLTE call, then handover to 5G network can be performed quickly, but call drop occurs when VoNR is not supported
Solution Approach 1:
The UE performs preliminary determination of VoNR support capability before sending measurement reports. The UE checks whether it and the 5G network support VoNR in advance, and only sends measurement reports when VoNR is supported, thereby preventing call drop while enabling fast handover when conditions are favorable.
Solution Approach 2:
The UE dynamically adjusts its measurement report sending behavior based on the determined VoNR support capability. When VoNR is supported, the UE sends measurement reports immediately to enable fast handover; when VoNR is not supported, the UE delays sending measurement reports to prevent call drop, thus adapting the handover process to current network conditions.
2Reliability
If the UE delays sending measurement reports until VoLTE call completion, then call drop is prevented when VoNR is not supported, but handover is delayed
Solution Approach 1:
The UE changes the timing parameter of measurement report sending based on the determined VoNR support capability. When VoNR is supported, the UE sends measurement reports without delay, enabling timely handover. When VoNR is not supported, the UE delays measurement report sending until call completion, preventing call drop. This conditional parameter adjustment resolves the contradiction between call continuity and handover speed.
3Adaptability or versatility
If the UE performs handover to 5G SA network during ongoing VoLTE call, then network mobility is improved, but call setup failures occur when VoNR is not supported
Solution Approach 1:
The UE performs preliminary determination of VoNR support capability before initiating handover to 5G SA network. By checking VoNR support in advance, the UE can determine whether to proceed with handover during an ongoing VoLTE call, thereby improving network mobility while preventing call setup failures caused by incompatible handover attempts.
Data Source
AI summary
A method of handling an ongoing call performed by a UE in a wireless network is provided. The method includes initiating a voice over long term evolution call in a 4G network, detecting that a 5G network entity has configured an inter radio access technology measurement indicating a change from the 4G network to a 5G network based on identification of the 5G network, determining whether at least one of the UE or the 5G network does not support a voice over new radio (VoNR) call with a 5G cell, in response to determining that the at least one of the UE or the 5G network does not support the VoNR call, delaying sending a measurement report until the VOLTE call is completed, and in response to determining that both the UE and the 5G network support the VoNR call, sending the measurement report immediately for the 5G cell.