Radio Link Failure Detection in Enhanced Coverage Mode
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Solution Overview
Problem
In the enhanced coverage mode of LTE, user devices face challenges in detecting radio link failures due to low SINR conditions, which can lead to insufficient measurement time and frequent unexpected radio link failures when using standard timer thresholds designed for non-enhanced coverage modes.
Innovation Solution
A user device and radio communication method that allow for setting a radio link based on reduced reference reception power levels, with adjustable reception quality thresholds and timer values for each CE level, enabling appropriate radio link monitoring even in adverse conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard timer thresholds (T310/T311/N310/N311) for non-enhanced coverage mode are applied to MTC-UE in enhanced coverage mode, then the device can use conventional RLF detection parameters, but sufficient measurement time cannot be secured and unexpected RLF occurs frequently
Solution Approach 1:
The patent applies parameter changes by adjusting timer thresholds (T310, T311, N310, N311) and reception quality thresholds (Qin, Qout) specifically for enhanced coverage mode operations. These parameters are modified to account for the challenging propagation conditions and low SINR environments characteristic of MTC-UE deployments in basements and metal boxes, thereby securing sufficient measurement time and preventing unexpected RLF.
2Reliability
If reception quality thresholds are set for each reduced level (CE level), then the monitoring can be optimized for specific propagation conditions, but the device complexity increases
Solution Approach 1:
The patent implements local quality by configuring different reception quality thresholds (Qin and Qout) for each Coverage Enhancement level (CE level 0-3). This allows the radio link monitoring to be optimized for specific propagation conditions associated with each CE level, using appropriate thresholds that match the expected signal quality at each enhancement level without requiring complex real-time adjustments.
Data Source
AI summary
An object is to provide a user device and a radio communication method that are capable of appropriately detecting radio link failure (RLF) even when an enhanced coverage mode is in operation. UE (200) includes CE level setting unit (230) that sets, when the UE is set in the enhanced coverage mode, a reception quality threshold (Qin/Qout) of a reference reception power level (RSRP/RSRQ) specified for CE level, and a radio link monitoring unit (240) that executes radio link monitoring based on the set reception quality threshold. The CE level setting unit (230) sets, regardless of whether the UE (200) is set to any CE level or not, a reception quality threshold specified for the maximum CE level.