UPF Data Forwarding for Selective SCG Candidate Node Activation

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Solution Overview

Problem

The existing Conditional PSCell Change (CPC) procedures in 3GPP Rel-16 and Rel-17 result in unnecessary signaling burden and increased Xn interface overhead due to frequent data forwarding among candidate SNs, especially for applications requiring low latency data access.

Innovation Solution

A UPF network node is configured to directly forward user data to all candidate SNs, including the currently serving SN, without intermediaries like the Source MN, thereby reducing signaling overhead and latency by executing data forwarding based on an indication message.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If data forwarding is performed through Source MN to all candidate SNs in CPC procedures, then all candidate SNs receive user data for potential PSCell change, but signaling overhead and Xn interface overhead increase due to frequent updates

Engineering Contradiction:

Improvedata forwarding reliabilityVSAvoidsignaling overhead

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the data forwarding function from the control plane (Source MN) and places it directly in the user plane (candidate SNs). The UPF network node directly forwards user data to all candidate SNs without involving Source MN, separating control signaling from user data transmission and eliminating unnecessary signaling overhead while maintaining data forwarding reliability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces an indication message as an intermediary mechanism that triggers direct data forwarding from UPF to candidate SNs. This indication message contains necessary routing information, enabling the UPF to directly establish data paths to candidate SNs without requiring continuous involvement of Source MN, thus reducing signaling overhead while ensuring reliable data delivery

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If TEIDs are updated from source SN to candidate SNs after each PSCell change, then data flow routing is maintained, but unnecessary signaling occurs when candidate SN set remains the same

Engineering Contradiction:

Improvedata flow routingVSAvoidsignaling delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent performs preliminary configuration by providing the UPF network node with the complete set of candidate SNs and their routing information in advance through the indication message. This allows the UPF to maintain ready-to-use data paths to all candidate SNs, eliminating the need for reactive TEID updates after each PSCell change and reducing signaling delay while ensuring data flow routing reliability

Inventive Principle:

Principle #10Preliminary action

3Reliability

If MN continuously forwards data from source SN to candidate SNs, then all candidate SNs are prepared for potential PSCell change, but Xn interface overhead increases

Engineering Contradiction:

Improvecandidate SN preparationVSAvoidXn interface overhead

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent replaces the mechanical data forwarding mechanism through Source MN with a direct user plane forwarding mechanism from UPF to candidate SNs. By substituting the control plane-based forwarding (which requires Xn interface involvement) with user plane forwarding, the patent eliminates unnecessary Xn interface overhead while maintaining candidate SN preparation reliability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentEP4354958B1UPF based transmission of user data for selective activation of candidate nodes

Publication Date: 2026.02.11 NOKIA TECHNOLOGIES OY

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AI summary

Described herein is a User Plane Function, UPF, network node, configured for data forwarding for selective activation of a Secondary Cell Group, SCG, for serving a User Equipment, UE, the UPF network node comprising: at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the UPF network node at least to: receive an indication message for starting data forwarding; and execute data forwarding on the basis of the received indication message.