Cell Reselection Scheduling for Wireless Service Continuity

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Solution Overview

Problem

In wireless communication systems, back-to-back cell reselection failures lead to reselection delays and sub-optimal serving cell usage due to failed cell reselection, particularly in UMTS networks, resulting in inconsistent service quality.

Innovation Solution

A method and apparatus that determine when cell reselection to a primary candidate cell has failed during a discontinuous reception (DRX) cycle, triggering a set of predetermined conditions, and schedule cell reselection to a secondary candidate cell based on these conditions, ensuring continuous service by iteratively connecting to the best available cell.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If cell reselection is attempted to a primary candidate cell during DRX cycle, then service continuity is improved, but reselection delays occur when reselection fails

Engineering Contradiction:
Improveservice continuityVSAvoidreselection delays
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent identifies candidate cells in advance and prepares a list of potential target cells (primary and secondary candidates) before reselection failure occurs. When primary candidate reselection fails, the UE already has pre-identified secondary candidates ready to attempt, eliminating the need for time-consuming cell search and evaluation after failure.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent enables the UE to skip the normal cell selection and evaluation procedures when attempting reselection to secondary candidate cells. The UE directly attempts reselection to pre-identified secondary candidates without performing full cell reselection assessments, thereby rapidly recovering from reselection failures.

Inventive Principle:
Principle #21Skipping (Rushing through)

2Reliability

If multiple cell reselection attempts are made during DRX cycle, then service consistency is improved, but device complexity increases

Engineering Contradiction:
Improveservice consistencyVSAvoidreselection scheduling complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the cell reselection process into distinct stages: primary candidate cell reselection attempt, failure detection, and secondary candidate cell reselection attempt. Each stage has specific predetermined conditions and evaluation criteria, making the complex multi-attempt process more manageable and implementable through structured decision-making logic.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent changes the evaluation parameters and criteria when moving from primary to secondary candidate cells. Different measurement thresholds, evaluation metrics, and timing parameters are applied to secondary candidates compared to primary candidates, enabling the system to adapt its reselection strategy based on the reselection attempt stage without requiring completely separate complexity-intensive procedures.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2989825B1Method and apparatus for back to back reselection scheduling upon cell reselection failure
Publication Date: 2017.09.13 QUALCOMM INC
  • EP2989825B1 patent drawingFigure 1
  • EP2989825B1 patent drawingFigure 2
  • EP2989825B1 patent drawingFigure 3

AI summary

Methods and apparatus for wireless communication for improving back to back cell reselection that includes establishing that cell reselection to a primary candidate cell has failed. Afterwards, a UE determines if a set of predetermined conditions have been triggered and schedules cell reselection to a secondary candidate based on whether the set of predetermined conditions have been triggered.