Link Budget Limited Device Cell Reselection Threshold Adjustment

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Solution Overview

Problem

Link budget limited devices face challenges in cell selection and reselection due to aggressive signal strength threshold values set for traditional devices, leading to sub-optimal operation and potential loss of service.

Innovation Solution

User Equipment (UE) modifies signal strength threshold values by applying an offset based on its operating parameters and network-provided information to adapt cell selection and reselection processes, ensuring improved operation for link budget limited devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional signal strength threshold values are used for cell selection and reselection, then network operation is optimized for traditional devices, but link budget limited devices experience sub-optimal operation and potential service loss

Engineering Contradiction:
Improveservice continuityVSAvoiddevice compatibility
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent applies local quality by introducing device-specific threshold adjustments. Link budget limited devices apply an offset to the signal strength threshold values received from the network, while traditional devices use the thresholds as-is. This localized modification allows each device type to operate optimally within the same network without compromising overall compatibility.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent implements parameter changes by modifying the signal strength threshold parameter (qRxLevMin) based on device characteristics. The network provides a base threshold value, and link budget limited devices adjust this parameter by adding an offset value specific to their link budget constraints, thereby adapting the threshold to their reduced reception capabilities.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If signal strength thresholds are lowered to accommodate link budget limited devices, then these devices can camp on cells, but traditional devices may experience inappropriate cell selection

Engineering Contradiction:
Improvecell camping successVSAvoidthreshold accuracy
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies dynamics by making the threshold value adaptive rather than static. The threshold dynamically adjusts based on device type: link budget limited devices receive a modified threshold (base threshold + offset) while traditional devices use the base threshold. This dynamic adjustment ensures each device type maintains appropriate threshold accuracy for its specific capabilities.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent segments the threshold application by device category. Instead of using a single universal threshold, the system divides threshold application into separate paths: one for link budget limited devices with offset adjustment and another for traditional devices using the base threshold. This segmentation preserves threshold accuracy for each device segment.

Inventive Principle:
Principle #1Segmentation

3Reliability

If offset values are applied to threshold values, then link budget limited devices can successfully camp on cells, but additional processing complexity is introduced

Engineering Contradiction:
Improvecell selection successVSAvoidthreshold processing
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements self-service by enabling link budget limited devices to automatically determine and apply their own offset values based on their inherent link budget characteristics. The device autonomously calculates the adjusted threshold without requiring complex network interaction or additional configuration, thereby limiting the increase in processing complexity to a simple additive operation.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP3326409B1Cell reselection for link budget limited devices
Publication Date: 2021.05.05 APPLE INC
  • EP3326409B1 patent drawingFigure 1~2
  • EP3326409B1 patent drawingFigure 3
  • EP3326409B1 patent drawingFigure 4

AI summary

Some embodiments relate to a user equipment (UE) configured to modify at least one signal strength threshold value to provide improved operation for link budget limited devices when performing cell selection or reselection. In some embodiments, the UE may receive a threshold value indicating a minimum received signal strength for camping on a cell. The UE may determine an offset value based on operating parameters of the UE, and may determine a modified threshold value by applying the offset value to the received threshold value. The UE may then compare the modified threshold value to a signal strength measurement of a signal received from a base station associated with the cell. The UE may camp on the cell if the modified threshold value is less than the signal strength measurement, and not camp on the cell if the modified threshold value is greater than the signal strength measurement.