5G UE Fallback Handover Optimization via Signal Measurement
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Solution Overview
Problem
Current 5G cellular networks experience voice service delays and failures due to reliance on intermittent 4G LTE signals during fallback procedures, leading to increased call setup times and service failures, especially when 5G UE initiates voice services over weak 4G signals.
Innovation Solution
The 5G UE sends a measurement report to the 5G base station during call setup, providing current signal strength information for various frequencies, allowing the base station to automatically select the optimal LTE frequency for voice services, thereby reducing call setup delays and improving call success rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the 5G UE initiates voice service over 5G NR, then the data rate and latency are improved, but the voice service may fail or experience delays when 4G LTE signal is weak or intermittent
Solution Approach 1:
The system performs preliminary measurements of 4G LTE signal strength before initiating EPS fallback. The UE measures the signal strength of candidate 4G cells and reports this information to the 5G base station in advance, allowing the base station to assess whether the 4G signal is strong enough to support voice service before committing to the fallback procedure.
Solution Approach 2:
The UE provides feedback about 4G LTE signal strength measurements to the 5G base station. This feedback mechanism allows the base station to make informed decisions about whether to initiate EPS fallback based on actual measured signal conditions, rather than blindly attempting fallback without knowing the target 4G cell's signal quality.
2Reliability
If the UE performs EPS fallback to 4G LTE, then voice service reliability is improved, but call setup delay increases by approximately 2 seconds
Solution Approach 1:
The UE performs 4G LTE signal strength measurements and prepares measurement reports before the base station initiates EPS fallback. By having measurement data ready in advance, the handover execution can proceed more quickly once decided, reducing the overall call setup delay.
Solution Approach 2:
The UE autonomously performs measurements of neighboring 4G cells and generates measurement reports without requiring explicit triggering for each measurement. This self-service approach ensures measurement data is readily available when needed, eliminating measurement delays during the fallback decision process.
3Reliability
If the UE switches to 4G LTE for voice service, then voice call success rate is improved, but the UE may get stuck on 4G network adding extra delay to other services
Solution Approach 1:
The system implements dynamic cell reselection mechanisms that allow the UE to monitor both 5G NR and 4G LTE networks simultaneously after fallback. The UE can dynamically switch back to 5G NR when conditions permit, preventing permanent attachment to 4G and reducing service delays for non-voice applications.
Solution Approach 2:
The base station can adjust parameters such as reselection thresholds and timing to control when the UE should switch back from 4G to 5G. By changing these parameters dynamically based on network conditions, the system optimizes the balance between maintaining voice service reliability on 4G and minimizing delays for other services that benefit from 5G connectivity.
Data Source
AI summary
A system and method may improve service setup time and reliability for user equipment (UE) fallback procedures in cellular networks. Logic in the UE may define an event to trigger a measurement report and send that measurement report to the base station upon initiating fallback procedures. This event and measurement report may allow the 5G base station (g-NB) to know which frequency is going to be the best choice at the time of setting up the voice service by looking at radio signal strength indicators coming from the 5G UE for each frequency in the measurement report. Incorporating the measurement report process into the logic of the UE for call setup that also includes the fallback process for may result in substantially faster call setup time as well as better voice call success rate.