LTE-to-NR Redirection After EPS Fallback With Priority Measurement
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Solution Overview
Problem
The existing EPS Fallback technology results in a long delay during the reselection process from LTE to NR after a voice service ends, leading to a poor user experience due to the traditional reselection process in 5G networks with small coverage.
Innovation Solution
Maintaining an RRC connection with the LTE cell after VoLTE release and configuring a higher priority for NR cell measurement, triggering a redirection to NR when the NR cell's service quality meets a predetermined threshold, thereby reducing the delay and improving user experience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the traditional reselection process is used after EPS Fallback, then the UE can return to NR network, but the reselection delay is long (about 3 seconds)
Solution Approach 1:
The patent applies preliminary action by maintaining the RRC connection in a suspended state during the voice call on LTE network, rather than fully releasing it. This allows the UE to already have measurement configurations and connection parameters ready, so that when the voice call ends, the UE can immediately perform measurements and redirect to NR without going through the full reselection process, thereby reducing the return delay from about 3 seconds to much shorter time.
Solution Approach 2:
The patent implements dynamics by introducing a configurable RRC connection suspension mechanism that can be dynamically adjusted. The network can control whether to suspend or fully release the RRC connection based on service requirements, and the UE can dynamically switch between connected and idle states. This dynamic approach allows optimization of the balance between connection maintenance overhead and reselection delay.
2Loss of time
If the RRC connection is fully released after VoLTE release, then the UE enters idle mode, but the reselection to NR takes longer time
Solution Approach 1:
The patent applies preliminary action by maintaining the RRC connection in a suspended state with pre-configured measurement parameters and cell information, so that when the voice call ends, the UE can immediately utilize these pre-prepared resources to perform measurements and redirect to NR without needing to re-establish connections or perform extensive measurements from scratch, thereby reducing both time and energy consumption.
3Productivity
If the UE performs measurements of adjacent cells in idle mode, then the UE can reselect to NR, but the measurement priority is not optimized for NR
Solution Approach 1:
The patent applies local quality by introducing frequency-specific priority configurations that differentiate between NR and LTE cell measurements. The network can assign higher measurement priorities to NR frequencies, causing the UE to preferentially measure and select NR cells when available. This localized priority adjustment optimizes the measurement process to favor 5G NR network utilization without requiring complete reconfiguration of the measurement system.
Data Source
AI summary
The present disclosure relates to a method and device for redirection from LTE to NR after EPS Fallback. Disclosed is a method executed by user equipment for redirection from an LTE cell to an NR cell after EPS Fallback, including: after a VoLTE voice bearer is released, a user equipment maintains a RRC connection with an LTE cell, and measures the quality of service of a cell adjacent to the user equipment according to a cell connected mode frequency priority, wherein the priority of the NR cell is set to be higher than that of the LTE cell, so that the quality of service of the NR cell adjacent to the user equipment is measured first; and when the quality of service measurement result for the adjacent NR cell reaches a preset threshold, the user equipment redirects to the adjacent NR cell.