UE Cell Measurement for NB-IoT RLF Recovery
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Solution Overview
Problem
Narrowband Internet of Things (NB-IoT) devices experience radio link failure (RLF) leading to radio resource control (RRC) connection loss, causing service continuity issues due to time-consuming cell searching for suitable target cells during mobility, which is not suitable for mobile applications.
Innovation Solution
A cell measurement method in user equipment (UE) that evaluates signal quality in the serving cell, detects triggering events for neighbor cell measurements before RLF, performs neighbor cell measurements in the narrowband downlink channel, and reestablishes a connection with a selected target cell when conditions are met.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If neighbor cell measurements are performed after radio link failure (RLF), then the device can reestablish connection with a target cell, but the service continuity is restricted due to time-consuming cell searching
Solution Approach 1:
The patent applies preliminary action by performing neighbor cell measurements before radio link failure occurs. The UE continuously monitors serving cell signal quality and detects triggering events that indicate deteriorating conditions. When triggering events are detected, the UE proactively performs neighbor cell measurements and selects target cells in advance, so that when RLF actually occurs, the UE can immediately reestablish connection without time-consuming cell searching, thus resolving the contradiction between service continuity and cell searching time
2Loss of time
If the UE continuously monitors serving cell signal quality and performs early neighbor cell measurements, then connection reestablishment time is reduced, but device complexity increases
Solution Approach 1:
The UE continuously monitors serving cell signal quality and detects triggering events that indicate deteriorating conditions. When triggering events are detected, the UE proactively performs neighbor cell measurements and selects target cells in advance, so that when RLF actually occurs, the UE can immediately reestablish connection without time-consuming cell searching
Solution Approach 2:
The patent implements feedback mechanisms where the UE continuously evaluates signal quality of reference signals in the narrowband downlink channel, detects triggering events based on this evaluation, and adjusts its measurement behavior accordingly. This feedback-driven approach allows the UE to perform measurements only when necessary, reducing unnecessary complexity while maintaining fast reestablishment capability
Data Source
AI summary
A user equipment (UE) executes a cell measurement method to shorten the time from radio link failure to reconnect to a telecommunication network. The UE detects at least one of a plurality triggering events for neighbor cell measurements associated with evaluating of the signal quality of the reference signals in the narrowband downlink channel in the serving cell. The UE performs neighbor cell measurements on reference signals in a narrowband downlink channel in one or more neighbor cells in a cell measurement period in response to the at least one of a plurality triggering events. The neighbor cell measurements are performed before radio link failure (RLF) associated with the user equipment. The UE selects at least one target cell among the one or more neighbor cells through the neighbor cell measurements and performs a cell reestablishment procedure.