Cell Re-selection Priority in RRC Inactive State

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Solution Overview

Problem

Current wireless communication systems face challenges in efficiently managing cell re-selection while in an inactive state, leading to increased power consumption and unnecessary RNA updates, which affect battery life and network signaling efficiency.

Innovation Solution

A wireless device prioritizes cell re-selection within its current radio access network notification area (RNA) when in a radio resource control (RRC) inactive mode, reducing the need for RNA updates and minimizing power consumption by managing its own cell re-selection process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the wireless device performs cell re-selection without prioritizing cells within the current RNA, then the device can freely select any available cell, but this leads to increased RNA updates and higher power consumption

Engineering Contradiction:
Improvepower consumptionVSAvoidcell selection flexibility
Core Design Contradiction:
Use of energy by moving objectVSAdaptability or versatility

Solution Approach 1:

The patent changes the cell selection parameter by introducing RNA-based prioritization. When a cell is within the current RNA, it is assigned a higher priority value (e.g., priority +1) compared to cells outside the RNA (priority 0). This parameter modification guides the device to preferentially select cells within the current RNA, thereby reducing RNA update frequency and power consumption while maintaining reasonable selection flexibility.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the wireless device frequently updates RNA when moving between cells, then the device maintains accurate location information, but this increases signaling overhead and network load

Engineering Contradiction:
Improvelocation accuracyVSAvoidsignaling overhead
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The patent applies preliminary action by pre-defining the RNA (Radio Access Network Notification Area) before the device moves. The RNA is configured in advance with a list of cell identities, and the device is instructed to preferentially select cells within this pre-configured area. This preliminary configuration reduces the need for frequent RNA update signaling, as the device can operate within the predetermined RNA boundaries without continuous network communication.

Inventive Principle:
Principle #10Preliminary action

3Loss of energy

If the wireless device manages cell re-selection autonomously without network guidance, then the device reduces signaling overhead, but this may lead to suboptimal cell selection and reduced communication quality

Engineering Contradiction:
Improvesignaling overheadVSAvoidcell selection quality
Core Design Contradiction:
Loss of energyVSMeasurement precision

Solution Approach 1:

The patent segments the cell selection process into two parts: network-guided RNA configuration and device-autonomous cell selection within RNA. The network provides the RNA configuration (a segmented list of acceptable cell identities), and the device autonomously selects cells within this segmented framework using prioritization rules. This segmentation reduces signaling overhead compared to continuous network guidance while maintaining selection quality through the structured RNA constraints.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP3738400B1Cell re-selection while inactive
Publication Date: 2023.12.06 APPLE INC
  • EP3738400B1 patent drawingFigure 1~2
  • EP3738400B1 patent drawingFigure 3
  • EP3738400B1 patent drawingFigure 4

AI summary

This disclosure relates to performing cell re-selection while in an inactive state in a cellular communication system. A wireless device may establish a radio resource control connection with a cellular base station. The wireless device may receive an indication to enter a radio resource control inactive state. The wireless device may perform cell re-selection while in the radio resource control inactive state. Cells that are in the current radio access network notification area of the wireless device may be prioritized over cells that are not in the current radio access network notification area of the wireless device when performing cell re-selection while in the radio resource control inactive state.