Rank-Based Cell Reselection for Inaccessible RATs

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing cell reselection mechanisms in wireless communication systems, particularly in 5G NR, face challenges in efficiently switching to the highest priority Radio Access Technology (RAT) when the preferred RAT is inaccessible or barred, leading to suboptimal service quality and increased battery consumption.

Innovation Solution

The proposed solution enables User Equipment (UE) to perform a rank-based reselection procedure when it is unable to reselect to the RAT indicated in the reselection priority list, allowing the UE to switch to the highest ranked neighbor cell based on signal strength, even if it operates on a different RAT.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the UE performs a rank-based reselection procedure to connect to the highest priority RAT, then service quality is improved, but battery power consumption increases

Engineering Contradiction:
Improveservice qualityVSAvoidbattery power consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent changes the reselection mechanism from priority-based to rank-based, where the ranking parameters include signal strength measurements and QoS metrics. This allows the UE to dynamically adjust reselection decisions based on current network conditions and service requirements, improving service quality while managing power consumption through conditional reselection only when necessary

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent introduces dynamic reselection criteria where the UE evaluates multiple parameters (signal strength, QoS, RAT priority) in real-time rather than following static priority lists. This dynamic approach allows the system to adapt to changing network conditions and only trigger reselection when it truly improves service quality, thereby reducing unnecessary power consumption

Inventive Principle:
Principle #15Dynamics

2Speed

If the UE uses a priority-based reselection mechanism with reselection priority lists, then reselection speed is improved, but adaptability to inaccessible RATs deteriorates

Engineering Contradiction:
Improvereselection speedVSAvoidadaptability to inaccessible RATs
Core Design Contradiction:
SpeedVSAdaptability or versatility

Solution Approach 1:

The patent inverts the traditional approach by not relying on pre-configured priority lists that assume certain RATs are always accessible. Instead, it uses rank-based evaluation that adapts to actual network conditions, allowing the UE to flexibly select from available RATs regardless of their priority status, thus improving adaptability while maintaining reasonable reselection speed through efficient ranking algorithms

Inventive Principle:
Principle #13The other way round (Inversion)

3Measurement precision

If the UE performs complex signal strength measurements and rank calculations, then reselection accuracy is improved, but device complexity increases

Engineering Contradiction:
Improvereselection accuracyVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent creates a universal reselection framework that can handle multiple RATs (2G, 3G, 4G, 5G) and multiple measurement parameters through a single rank-based mechanism. This multi-functional approach consolidates what would otherwise require separate handling for each RAT and measurement type, improving reselection accuracy while actually reducing overall device complexity through standardization and unification of the reselection process

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP3707931B1Switching from a priority-based reselection mechanism to a rank-based reselection mechanism
Publication Date: 2025.03.05 QUALCOMM INC
  • EP3707931B1 patent drawingFigure 1
  • EP3707931B1 patent drawingFigure 2A~2D
  • EP3707931B1 patent drawingFigure 3

AI summary

In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may receive a priority list associated with preferred radio frequencies from a serving base station. In certain aspects, each radio frequency of the preferred radio frequencies associated with a first set of base station may operate on a first RAT. In certain other aspects, the apparatus may determine if the UE is able to reselect to the first RAT. In certain other aspects, the apparatus may perform a rank-based cell reselection procedure based on signal strength when the UE is unable to reselect to the first RAT.