Secondary Node SCG Release Signaling

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Solution Overview

Problem

Current 3GPP specifications lack clear methods for a Secondary Node (SN) to initiate the release of a Secondary Cell Group (SCG) configuration, specifically releasing PHY, MAC, and RLC layers while keeping SN-terminated Data Radio Bearers, leading to system performance degradation or long interruption delays.

Innovation Solution

Incorporating a flag in inter-node RRC messages and adding a new X2/Xn procedure to enable SN-initiated SCG release, allowing the SN to notify the Master Node (MN) to release SCG lower layers and convert SN-terminated Split or SCG DRBs to SN-terminated MCG DRBs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If current 3GPP specifications are used for SCG release, then the SN cannot initiate SCG configuration release, but this leads to system performance degradation and long interruption delays

Engineering Contradiction:

ImproveSCG release efficiencyVSAvoidinterruption delays

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The SCG configuration is segmented into different layers (PHY, MAC, RLC, PDCP), allowing selective release of lower layers (PHY, MAC, RLC) while maintaining PDCP layer and SN-terminated DRBs. This segmentation enables the SN to initiate partial SCG release without complete SCG teardown, improving release efficiency while reducing interruption delays.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A new X2/Xn procedure is introduced as an intermediary mechanism between SN and MN, enabling the SN to initiate SCG release by sending indication messages to the MN. The MN then coordinates the actual release with the UE, providing a controlled release path that avoids performance degradation and long interruptions.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If SN-initiated SCG release is implemented, then network flexibility is enhanced, but signaling complexity between nodes increases

Engineering Contradiction:

Improvenetwork flexibilityVSAvoidsignaling complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The SCG release initiation function is extracted from the MN and assigned to the SN. The SN can now independently decide when SCG release is needed and initiate the release procedure by sending indication messages to the MN, enhancing network flexibility without requiring complex re-architecting of the overall system.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The SN performs preliminary assessment and decision-making regarding SCG release needs, then initiates the release procedure through standardized X2/Xn signaling. This preliminary action by the SN avoids waiting for MN-initiated procedures, providing faster and more flexible SCG release while using existing signaling frameworks to minimize complexity increase.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentEP4282223B1Signaling for releasing a secondary cell group (SCG) configuration

Publication Date: 2024.05.29 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

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AI summary

Method, performed by a first network node operating as a secondary node, SN, in dual-connectivity, DC, with a user equipment, UE. The method comprises sending (1010), towards a second network node operating as a master node, MN, in dual-connectivity with the UE, an indication that a secondary cell group, SCG, configuration for the UE is to be released.