VoNR to VoLTE Fallback Manager for Handover Failure Recovery
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current communication systems face challenges in ensuring seamless voice over new radio (VoNR) to voice over long term evolution (VoLTE) fallback, leading to poor quality of service due to handover failures, as neither the user equipment (UE) nor the target RAN node can deterministically identify the cause of handover or radio resource control redirection, resulting in incorrect fallback decisions.
Innovation Solution
Implementing a fallback manager in both user equipment (UE) and base stations to detect handover failures and take corrective actions, such as performing cell selection or re-selection based on EPS/Inter-RAT fallback indications, using extended timers for LTE cell search, and autonomously searching for voice-capable cells, to ensure successful VoNR-to-VoLTE fallback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE performs standard handover procedure without fallback detection mechanism, then the handover process is simple, but the fallback reliability deteriorates due to inability to identify handover cause
Solution Approach 1:
The patent applies preliminary action by having the network node provide fallback indication information to the UE before the handover is actually needed. This allows the UE to be pre-configured with the knowledge that a fallback to LTE is expected, enabling proper detection and handling of the fallback scenario without adding complex real-time detection mechanisms during the handover execution phase.
Solution Approach 2:
The patent implements feedback by having the UE send a measurement report containing the fallback indication information back to the network node. This feedback mechanism allows the network to verify whether the UE has correctly received and understood the fallback indication, enabling the network to adjust its behavior accordingly and improve overall fallback reliability.
2Ease of operation
If the UE returns to NR after handover failure, then the UE follows standard procedure, but the voice service quality deteriorates because NR may not support voice calls
Solution Approach 1:
The patent applies preliminary action by configuring the UE with fallback indication information before handover, which instructs the UE on the expected target RAT for voice calls. When handover fails, the UE can immediately apply this pre-configured knowledge to select an appropriate cell on the indicated RAT (e.g., LTE) without needing to return to NR, thus maintaining voice service continuity while keeping the operation simple.
Solution Approach 2:
The patent implements self-service by enabling the UE to autonomously determine the appropriate action after handover failure based on the fallback indication information it received. The UE independently decides to perform cell selection or re-selection on the indicated RAT without requiring complex network control or additional signaling, thereby simplifying the overall system operation while ensuring reliable voice service.
3Adaptability or versatility
If the UE performs cell search on all RATs after handover failure, then the UE maximizes coverage search, but the time to establish voice service increases
Solution Approach 1:
The patent applies local quality by directing the UE to perform cell search and selection only on the specific RAT indicated by the fallback indication information (e.g., LTE), rather than searching all available RATs. This localized approach concentrates the search effort on the most relevant RAT for voice service, significantly reducing the time to establish voice service while maintaining adaptability through network-configurable indications.
Solution Approach 2:
The patent implements parameter changes by modifying the UE's cell selection behavior based on the fallback indication information received from the network. The network can dynamically change the indicated RAT parameter in the fallback indication, allowing the UE to adapt its search parameters accordingly. This enables the system to balance between search comprehensiveness and establishment time by adjusting which RATs the UE should prioritize searching.
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
Certain aspects of the present disclosure relate to methods and apparatus for improving voice over new radio (VoNR)-to-voice over long term evolution (VoLTE). An example method generally includes communicating with and camping on a next generation node B (gNB) in a 5G new radio (NR) system; initiating a voice call with the gNB; receiving a 5G NR-to-long term evolution (LTE) handover command in response to initiating the voice call; performing a handover procedure in response to the handover command; detecting a failure in the handover procedure; and taking one or more actions in response to detecting the failure in the handover procedure.