IAB Relay Conditional Handover for Backhaul Link Failures

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Solution Overview

Problem

Existing cellular communication systems face challenges in managing radio link failures (RLF) in backhaul links of integrated access and backhaul (IAB) nodes, leading to communication disruptions and inefficient recovery mechanisms, particularly in scenarios involving mobile IAB nodes and frequent topology changes.

Innovation Solution

The implementation of enhanced BH RLF indication methods, including Type 2 and Type 3 notifications, conditional handover configurations, and dynamic route priority adjustments, along with alternative path activation, to facilitate quicker and more controlled recovery from RLFs in multi-hop wireless relay networks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional RLF detection and recovery mechanisms are used in IAB nodes, then basic communication continuity is maintained, but communication disruptions occur during backhaul link failures and recovery is inefficient in dynamic topology scenarios

Engineering Contradiction:
Improvecommunication continuityVSAvoidrecovery time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent implements conditional handover configurations where the IAB node pre-configures alternative paths and handover conditions before backhaul link failures occur. When RLF is detected, the node can immediately execute pre-planned handover to alternative parent nodes without waiting for conventional recovery procedures, significantly reducing recovery time while maintaining communication continuity

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent introduces dynamic route priority adjustments that allow the IAB node to adaptively change the priority of different backhaul routes based on real-time link conditions. This enables the system to dynamically switch between conventional and alternative paths, optimizing recovery efficiency in changing topology scenarios while ensuring reliable communication

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If frequent topology changes are accommodated in mobile IAB nodes, then network flexibility and adaptability improve, but communication stability and reliability deteriorate due to increased RLF occurrences

Engineering Contradiction:
Improvenetwork flexibilityVSAvoidcommunication stability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent pre-configures multiple alternative paths and handover conditions in mobile IAB nodes before topology changes occur. When RLF is detected due to topology changes, the node can immediately execute pre-planned handover to alternative parent nodes, maintaining communication stability while accommodating network flexibility and adaptability

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements enhanced BH RLF indication mechanisms that provide real-time feedback on backhaul link conditions to the IAB node. This feedback enables the node to proactively adjust routes and priorities before complete link failure occurs, maintaining communication stability in dynamically changing network conditions

Inventive Principle:
Principle #23Feedback

3Ease of operation

If multiple notification types (Type 2 and Type 3) are implemented for RLF indication, then recovery control and route adaptation improve, but system complexity increases

Engineering Contradiction:
Improverecovery controlVSAvoidsystem complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent segments the RLF indication mechanism into multiple notification types (Type 1, Type 2, Type 3) with distinct functions. Type 1 provides basic RLF detection, Type 2 provides enhanced control for specific scenarios, and Type 3 provides additional route adaptation capabilities. This segmentation allows the system to implement complex recovery control by combining simple, well-defined notification types rather than implementing a single complex mechanism

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent designs the multiple notification types to work within a unified conditional handover framework, where each notification type can trigger appropriate handover actions based on pre-configured conditions. This multi-functional approach allows the same handover mechanism to handle different RLF scenarios efficiently, improving ease of operation without proportionally increasing system complexity

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP4224902B1Communication control method
Publication Date: 2025.07.02 KYOCERA CORP
  • EP4224902B1 patent drawingFigure 1
  • EP4224902B1 patent drawingFigure 2
  • EP4224902B1 patent drawingFigure 3

AI summary

A communication control method according to a first aspect is a communication control method used in a cellular communication system. The communication control method includes transmitting, by a relay node that detects occurrence of a failure in a backhaul link between the relay node and a parent node of the relay node, a notification instructing execution of a conditional handover, and receiving, by a communication apparatus, the notification.