IAB Node Group Handover Signaling in Inter-CU Migration

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Solution Overview

Problem

Current 5G New Radio (NR) networks face challenges in inter-Central Unit (inter-CU) migration for Integrated Access and Wireless Backhaul (IAB) handover, leading to service interruptions and increased signaling load due to the lack of standardized group handover procedures for IAB nodes and UEs.

Innovation Solution

Implement a layered approach for signaling handover commands, where the target Central Unit (CU) prepares and transmits handover commands for affected UEs and IAB nodes, allowing for efficient group signaling and reducing the need for individual message transmission, thereby minimizing handover delay and potential performance degradation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If individual handover commands are transmitted to each IAB node and UE separately, then handover control precision is maintained, but signaling load increases and handover delay increases

Engineering Contradiction:

Improvehandover control precisionVSAvoidhandover delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent combines multiple individual handover commands into a single group handover command that is transmitted to the IAB node. This group command contains handover instructions for multiple UEs simultaneously, reducing the number of signaling messages while maintaining the precision of individual handover control. The IAB node then distributes these commands to the respective UEs, achieving both efficiency and accuracy.

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If individual handover commands are transmitted to each IAB node and UE separately, then handover control precision is maintained, but signaling load increases

Engineering Contradiction:

Improvehandover control precisionVSAvoidsignaling load

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent merges multiple handover commands into a single group handover command transmitted from the target gNB-CU to the IAB node. This consolidation significantly reduces the quantity of signaling messages required during inter-CU migration, while the IAB node maintains the ability to distribute and manage individual handover instructions for each UE within the group command structure.

Inventive Principle:

Principle #5Merging (Combining)

3Productivity

If group handover signaling is implemented, then signaling load is reduced and handover delay is minimized, but handover control precision may be compromised

Engineering Contradiction:

Improvehandover efficiencyVSAvoidhandover control precision

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent segments the group handover command into two parts: a master group command transmitted to the IAB node containing common handover parameters, and individual UE-specific commands distributed by the IAB node to each UE. This segmentation maintains handover control precision by preserving UE-specific instructions while achieving the efficiency benefits of group signaling through the consolidated master command.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS20230247495A1IAB node handover in inter-CU migration

Publication Date: 2023.08.03 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

A method is performed by a target Central Unit (CU) during a handover of a migrating node from source CU and source Distributed Unit (DU) to the target CU and a target DU. The method includes transmitting, to the target DU, a first handover command for at least one child node of the migrating node being handed over from the source CU and source DU to the target CU and target DU.