Conditional PSCell Change Coordination Between MN and SN

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Solution Overview

Problem

In Rel-17, the issue arises when a master node (MN) and a secondary node (SN) independently prepare conditional PSCell changes for a user equipment (UE), leading to conflicts and ambiguity, as the MN is not aware of SN-configured intra-SN CPCs, which become invalid upon UE execution.

Innovation Solution

The MN notifies the SN about intended MN-initiated CPC, and the SN provides the updated SCG configuration to the MN after intra-SN CPC execution, ensuring coordination and avoiding conflicts by using separate signaling for data forwarding needs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If MN and SN independently prepare conditional PSCell changes, then preparation efficiency is improved, but conflicts and ambiguity occur due to lack of coordination

Engineering Contradiction:

Improvepreparation efficiencyVSAvoidcoordination accuracy

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The source SN sends a notification message to the MN after executing intra-SN conditional PSCell change, providing feedback about the execution status. This feedback mechanism allows the MN to update its state and avoid conflicts between independent preparation procedures.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

A notification message serves as an intermediary carrier between the source SN and MN, transmitting execution status information. This intermediary enables indirect communication and coordination between the two nodes that were previously operating independently.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If MN is not aware of SN-configured intra-SN CPCs, then device complexity is reduced, but conflicts occur when UE executes invalid configurations

Engineering Contradiction:

Improveinformation awarenessVSAvoidconfiguration validity

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The source SN performs preliminary action by sending a notification message to the MN before the UE executes the intra-SN conditional PSCell change. This advance notification allows the MN to prepare for the configuration change and avoid using invalid configurations.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The notification message provides feedback from the source SN to the MN about the intra-SN CPC execution status, enabling the MN to update its knowledge state and maintain configuration validity without requiring continuous awareness of all SN operations.

Inventive Principle:

Principle #23Feedback

3Reliability

If separate signaling is used for data forwarding needs, then coordination accuracy is improved, but signaling overhead increases

Engineering Contradiction:

Improvecoordination accuracyVSAvoidsignaling overhead

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The notification message serves multiple functions simultaneously: it notifies the MN about intra-SN CPC execution status and carries information about data forwarding needs. This multi-functionality reduces the need for separate dedicated signaling messages for each purpose.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentEP4381796B1Update of MN-initiated inter-sn conditional pscell change

Publication Date: 2026.02.18 NOKIA TECHNOLOGIES OY

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AI summary

A method includes transmitting a configuration to a user equipment, the configuration comprising a conditional cell change initiated with a master node; and transmitting a notification to a source secondary node from the master node in response to a preparation of the conditional cell change, the notification being related to the conditional cell change initiated with the master node; wherein the notification comprises an indication of whether the source secondary node is to perform early data forwarding from the source secondary node to a target secondary node.