IAB Distributed Unit Multi-CU Connection for Inter-Donor Migration

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Solution Overview

Problem

Existing technologies do not clearly outline how IAB-nodes should manage context and establish connections, particularly F1 connections, during inter-donor migration in integrated access and backhaul (IAB) scenarios.

Innovation Solution

A distributed unit (DU) of an IAB-node establishes connections with multiple centralized units (CUs) by creating a first connection with a first CU and a second connection with a second CU via the first CU, enabling seamless inter-donor migration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If an IAB-node establishes F1 connections to multiple CUs during inter-donor migration, then migration capability and adaptability are improved, but connection management complexity increases

Engineering Contradiction:
Improveinter-donor migration capabilityVSAvoidconnection management complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by establishing the first F1 connection to a first CU before migrating to a second CU. The IAB-node proactively sets up the initial connection, maintains it during migration, and only then establishes the second connection to the target CU. This sequential approach prevents the complexity of managing multiple simultaneous connections while enabling smooth inter-donor migration.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If F1 connections are established during inter-donor migration, then migration seamlessness is improved, but signaling overhead increases

Engineering Contradiction:
Improvemigration seamlessnessVSAvoidsignaling overhead
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent implements continuity of useful action by maintaining the first F1 connection active throughout the migration process. Rather than tearing down the existing connection and establishing a new one, the system keeps the original connection operational while adding the second connection. This continuous connection approach ensures seamless migration with minimized signaling interruptions and reduced overall signaling overhead.

Inventive Principle:
Principle #20Continuity of useful action

Data Source

PatentEP4272511B1Managing connections to multiple centralized units
Publication Date: 2025.12.03 GOOGLE LLC
  • EP4272511B1 patent drawingFigure 1A
  • EP4272511B1 patent drawingFigure 1B~2A
  • EP4272511B1 patent drawingFigure 2B

AI summary

A distributed unit (DU) operating in a radio access network (RAN) for establishing a connection with a centralized unit (CU) operating in the RAN, (i) transmits (1802), to a first CU, a first interface message to establish a first connection between the DU and the first CU, and (ii) transmits (1804), to a second CU via the first CU, a second interface message to establish a second connection between the DU and the second CU via the first CU, to maintain the first connection and the second connection concurrently.