Context Transfer for RRC Re-establishment in Heterogeneous Networks

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Solution Overview

Problem

In communication systems like LTE, Radio Link Failures (RLF) or handover failures often lead to unsuccessful Radio Resource Control (RRC) connection re-establishment, especially in heterogeneous networks, resulting in interrupted services and poor user experience due to the UE reconnecting to cells without its context information.

Innovation Solution

A method and apparatus that maintain connections between network nodes and user equipment (UE) to determine and transfer context information from one network node to another upon link failure, ensuring the target node has the necessary context for successful RRC re-establishment, such as security keys and information, facilitating a smooth handover.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the UE re-establishes connection to a cell without context information, then the re-establishment procedure fails and UE returns to idle mode, but this causes service interruption and poor user experience

Engineering Contradiction:
ImproveRRC connection re-establishment success rateVSAvoidservice continuity
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The source network node proactively transfers UE context information to the target network node before the UE actually performs re-establishment. This preliminary action ensures that when the UE needs to re-establish connection, the target node is already prepared with the necessary context, eliminating the failure that would otherwise occur when reconnecting to a node without context information

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The source network node acts as an intermediary that receives the UE context from the UE's previous connection and forwards it to the target network node. This intermediary transfer mechanism ensures that context information reaches the target node reliably, enabling successful re-establishment without service interruption

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If the UE reconnects to a cell without context information, then the connection can be re-established, but the service is interrupted and user experience deteriorates

Engineering Contradiction:
Improveconnection re-establishment capabilityVSAvoidservice continuity
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

Context information is transferred in advance to the target network node before the UE attempts re-establishment. This ensures that when the UE connects to the target cell, the node is already equipped with the necessary context, maintaining both ease of re-establishment and service continuity without interruption

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP2813125B1A method and apparatus for enhanced connection control
Publication Date: 2019.03.27 NOKIA TECHNOLOGIES OY
  • EP2813125B1 patent drawingFigure 1
  • EP2813125B1 patent drawingFigure 2
  • EP2813125B1 patent drawingFigure 3

AI summary

A method for enhanced connection control may comprise: maintaining a first connection between a first network node and a user equipment which has a second connection with a second network node; determining a third network node for re-establishing a third connection between the third network node and the user equipment, in response to a link failure of the second connection; and transferring context information of the user equipment from the first network node to the third network node.