Master Node SN Change Coordination

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Solution Overview

Problem

In the context of LTE DC, the Secondary Node (SN) is not aware of the Master Node (MN) initiated SN change procedure until it receives a release message, leading to potential conflicts and errors due to SCG configuration changes during the transition, as the SN may modify the UE's SCG configuration differently than expected.

Innovation Solution

A message is transmitted by the Master Node to the Secondary Node indicating that an SN change is pending, preventing the SN from performing SCG reconfigurations or triggering any SN-initiated procedures during the MN initiated SN change procedure, ensuring synchronization and avoiding configuration conflicts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the SN is allowed to perform SCG reconfigurations autonomously during MN initiated SN change procedure, then the SN can independently optimize UE configuration, but configuration conflicts and race conditions occur between MN and SN

Engineering Contradiction:

ImproveSN autonomous configuration capabilityVSAvoidconfiguration consistency

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The MN sends a notification message to the SN before initiating the SN change procedure, informing the SN to suspend SCG reconfigurations. This preliminary action prevents the SN from making configuration changes that could conflict with the upcoming SN change, ensuring configuration consistency while allowing the SN to resume autonomous optimization after the change is complete.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If the SN changes configuration during SN transition, then configuration can be updated, but race conditions and errors occur due to lack of SN awareness

Engineering Contradiction:

Improveconfiguration update speedVSAvoidprocedure reliability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The MN provides feedback to the SN by sending a notification message that indicates an SN change is pending. This feedback mechanism allows the SN to awareness of the MN's intentions and adjust its behavior accordingly, suspending configuration updates during the critical transition period to prevent race conditions while maintaining procedure reliability.

Inventive Principle:

Principle #23Feedback

3Reliability

If the SN is notified early about pending SN change, then configuration conflicts are avoided, but additional signaling messages are required

Engineering Contradiction:

Improveconfiguration synchronizationVSAvoidsignaling overhead

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The notification message serves multiple functions: it informs the SN of the pending SN change, requests suspension of SCG reconfigurations, and acts as a coordination signal between MN and SN. By making this single message multi-functional, the solution achieves configuration synchronization without proportionally increasing signaling overhead.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS11265776B2Master node, a secondary node and methods performed therein

Publication Date: 2022.03.01 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

Embodiments herein relate e.g. to a method performed by a master node (QQ160) for handling communication of a wireless device (QQ110) in a wireless network. The master node (QQ160) transmits, to a secondary node, SN, a message before initiating a SN change procedure, which message indicates that an SN change is pending and as such the SN should not perform either a secondary cell group, SCG, reconfiguration or trigger any SN triggered procedures.