VoWiFi Handover Logic to Avoid Cellular Fallback Loops
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Solution Overview
Problem
Existing wireless communication systems face inefficiencies in managing voice over Wi-Fi to voice over cellular handovers, particularly due to unnecessary fallbacks and suboptimal handover decisions that disrupt voice calls.
Innovation Solution
A method and apparatus for a user equipment (UE) to determine conditions for handovers between radio access technologies (RATs) that avoid unnecessary fallbacks by considering signal strengths, preferences, and stored cell identifiers, allowing for more optimal handover decisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If handover from Wi-Fi to cellular is performed based on signal strength thresholds, then connection reliability is improved, but unnecessary fallbacks occur causing call disruptions
Solution Approach 1:
The system performs preliminary evaluation of target cell characteristics (checking if cell ID is in the stored list of cells that trigger fallback) before executing handover. This preliminary action prevents unnecessary fallbacks by identifying problematic target cells in advance, thus improving handover efficiency while maintaining call reliability.
Solution Approach 2:
The system uses feedback from previous handover experiences by storing cell identifiers that have triggered fallbacks in the past. This feedback mechanism allows the UE to make informed handover decisions by referencing historical performance data, preventing repeated unnecessary fallbacks to the same problematic cells.
2Speed
If handover decisions are made quickly based on signal strength, then handover speed is improved, but suboptimal handover decisions occur
Solution Approach 1:
The system pre-loads and stores lists of cell identifiers that are known to trigger fallback during voice calls. When handover is needed, the UE can quickly check if the target cell is in this pre-prepared list, making fast handover decisions without compromising quality by avoiding cells known to cause problems.
3Reliability
If the system avoids cells that trigger fallback, then call continuity is improved, but handover options are reduced
Solution Approach 1:
The system creates a filtered copy of the available cell list by storing identifiers of cells that trigger fallback. This copied list is used specifically for voice call handover decisions, allowing the system to maintain full adaptability for other purposes while ensuring call continuity by excluding problematic cells from voice handover candidates.
Data Source
AI summary
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may determine, during an active call on a first radio access technology (RAT), a signal strength associated with the first RAT is within a particular range above a handover threshold. The UE may determine, based at least in part on a signal strength of a second RAT, that the active call would be moved from the second RAT to a third RAT after a handover from the first RAT to the second RAT, and, may trigger mobility from the second RAT to the third RAT based at least in part on the determination that the signal strength associated with the first RAT is within the particular range and the determination that the active call would be moved from the second RAT to the third RAT. Numerous other aspects are provided.