User Equipment Cell Reselection Fallback Logic

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Solution Overview

Problem

In a mobile communication system, user equipment (UE) may not be able to appropriately perform a cell reselection procedure when it receives an RRC release message with slice specific frequency priority information without also receiving slice priority information from the core network.

Innovation Solution

The UE ignores the slice specific frequency priority information when it receives an RRC release message without legacy frequency priority information and with slice specific frequency priority information, and instead performs a legacy cell reselection procedure using legacy frequency priority information from system information.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the UE uses slice specific frequency priority information from the RRC release message, then the UE can perform slice-aware cell reselection to camp on cells supporting intended network slices, but the UE cannot appropriately perform cell reselection when slice priority information is not available from the core network

Engineering Contradiction:

Improveslice-aware cell reselection capabilityVSAvoidcell reselection procedure reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The UE dynamically adapts its cell reselection behavior based on the availability of slice priority information. When slice priority information is available, the UE performs slice-specific cell reselection using the received slice specific frequency priority information. When slice priority information is not available, the UE automatically falls back to legacy cell reselection procedures, ensuring continuous operational reliability across different network conditions

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The UE changes the operational parameters of cell reselection based on information availability. The presence or absence of slice priority information triggers a parameter change in the reselection logic, switching between slice-aware mode (using slice specific frequency priority) and legacy mode (using traditional frequency priority from system information), thereby resolving the contradiction between advanced functionality and reliability

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If the RRC release message includes only slice specific frequency priority information without legacy frequency priority information, then the UE can support network slice-specific reselection, but the UE lacks fallback capability when slice priority information is unavailable

Engineering Contradiction:

Improvenetwork slice supportVSAvoidreselection logic complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The cell reselection logic is segmented into distinct pathways: slice-specific reselection when slice priority information is available, and legacy reselection when it is not. This segmentation allows the UE to clearly differentiate between operational modes and select the appropriate procedure, managing complexity through structured decision-making rather than attempting to handle all cases within a single unified logic

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of requiring the RRC release message to include both slice specific and legacy frequency priority information simultaneously, the invention inverts the approach by having the UE detect the absence of legacy information and automatically substitute slice specific information. This inversion simplifies the message structure while maintaining functional completeness through conditional logic at the UE side

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS20250184979A1Communication control method

Publication Date: 2025.06.05 KYOCERA CORP

AI summary

A communication control method according to one aspect is a communication control method in a mobile communication system. The communication control method includes a step of, by a user equipment, ignoring slice specific frequency priority information when receiving an RRC release message from a base station without receiving slice priority information from a core network apparatus, the slice priority information indicating a priority of a network slice, the RRC release message not including legacy frequency priority information and including the slice specific frequency priority information, the legacy frequency priority information indicating a priority per frequency, the slice specific frequency priority information indicating a priority of a frequency supporting the network slice.