Adaptive Cell Reselection Timer for Wireless Devices

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Solution Overview

Problem

Current wireless communication systems face inefficiencies in cell reselection processes, leading to call setup failures and dropped calls due to slow reselection times when the signal quality of the serving cell deteriorates.

Innovation Solution

Implementing a method that starts a reselection timer for a neighbor cell when the signal quality of the serving cell falls below a first threshold and speeds up reselection based on the difference between the serving cell and neighbor cell signal qualities when the serving cell's signal quality drops below a second threshold, allowing for expedited cell reselection before the scheduled timer expiration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a reselection timer is used for cell reselection, then call setup failures and dropped calls are reduced, but reselection time is increased

Engineering Contradiction:
Improvecall setup failure rateVSAvoidreselection time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent applies dynamics by making the reselection timer value adaptive rather than fixed. The timer is dynamically adjusted based on the mobility state of the user equipment, which is determined by counting the number of cell reselections within a specific time period. When the UE is identified as highly mobile, the timer is set to a shorter duration; when less mobile, a longer duration is used. This dynamic adjustment resolves the contradiction by optimizing the timer value according to actual movement conditions, reducing both call failures and unnecessary time delays.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of reselection timer duration based on measured mobility conditions. By monitoring the number of cell reselection events and comparing it against a threshold within a measurement period, the system adjusts the timer parameter to match the UE's mobility characteristics. This parameter change strategy allows the system to adapt to different scenarios, preventing both premature reselection (which causes call failures) and excessive waiting (which increases loss of time).

Inventive Principle:
Principle #35Parameter changes

2Loss of time

If fast cell reselection is implemented, then reselection time is reduced, but unnecessary reselection in stable areas increases

Engineering Contradiction:
Improvereselection timeVSAvoidunnecessary reselection frequency
Core Design Contradiction:
Loss of timeVSReliability

Solution Approach 1:

The patent uses dynamics to adjust the reselection timer based on the UE's mobility state. By continuously monitoring cell reselection events and determining whether the UE is highly mobile or less mobile, the system dynamically sets the timer to appropriate values. In stable areas with low mobility, the timer remains longer, preventing unnecessary fast reselection. In high-mobility areas, the timer is shortened to enable rapid reselection, thus resolving the contradiction between fast reselection and unnecessary reselection frequency.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent implements feedback by monitoring the number of cell reselections within a measurement period and using this information to adjust future reselection behavior. The system counts reselection events, compares them against a threshold, and determines the mobility state accordingly. This feedback loop ensures that fast reselection is only activated when actually needed (in high-mobility scenarios), preventing unnecessary reselection in stable areas while enabling fast reselection when mobility requires it.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP3398374B1Fast cell reselection
Publication Date: 2021.04.21 QUALCOMM INC
  • EP3398374B1 patent drawingFigure 1
  • EP3398374B1 patent drawingFigure 2
  • EP3398374B1 patent drawingFigure 3

AI summary

A user equipment (UE) expedites cell reselection. In one instance, the UE startsa reselection timer for reselecting to a neighbor cell when a signal quality of a serving cell is determined to fall below a first threshold. The UE then expedites reselecting to the neighbor cell based on a difference between the signal quality of the serving cell and the signal quality of the neighbor cell when the signal quality of the serving cell falls below a second threshold.