IAB Node Handover Signaling for Faster UE Reconnection

Solution Overview

Problem

Existing communication systems face delays in resuming data communication for user equipment (UE) after a radio link failure (RLF) occurs in Integrated Access and Backhaul (IAB) networks, particularly when the UE fails to reconnect promptly to a new IAB donor due to the IAB node not being ready to communicate during the switch.

Innovation Solution

A communication apparatus equipped with a determination unit to assess whether to switch the UE's connection from a first base station to a second, and a requesting unit to transmit a handover request message with a cell identifier, facilitating rapid reconnection of the UE to a new IAB donor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the IAB node switches connection to a new IAB donor after BH RLF, then backhaul communication can be recovered, but the UE cannot promptly reconnect to the new IAB donor because the IAB node is not ready to communicate during the switch

Engineering Contradiction:

Improvebackhaul communication recoveryVSAvoidUE reconnection delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies preliminary action by having the IAB node prepare and notify the UE about the upcoming handover to a new IAB donor before the actual connection switch occurs. The IAB node transmits a handover request message to the UE including cell identifier information, allowing the UE to prepare for reconnection in advance. This preliminary notification mechanism ensures the UE is ready to connect promptly once the IAB node finishes switching to the new donor, eliminating the delay where the UE would otherwise search for base stations after the RLF detection timer expires.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If the UE waits for the RLF detection timer to expire before searching for a base station, then the UE can detect disconnection, but the UE cannot find the new IAB node because it has not resumed base station function yet

Engineering Contradiction:

Improvedisconnection detectionVSAvoidbase station search capability

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent applies feedback by implementing a handover request message transmission mechanism where the IAB node provides feedback information (cell identifier) to the UE about the new base station it is connecting to. This feedback allows the UE to know in advance which base station to search for and connect to, rather than having to search blindly after the RLF detection timer expires. The feedback mechanism ensures the UE receives accurate information about the new IAB node's identity and location, enabling successful and prompt reconnection.

Inventive Principle:

Principle #23Feedback

3Adaptability or versatility

If the IAB node stops the DU connected to the old IAB donor and starts a new DU for the new IAB donor, then communication can be recovered through a different donor, but it takes time for the UE to be reconnected to the new IAB donor

Engineering Contradiction:

ImproveIAB donor switching capabilityVSAvoidUE reconnection time

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

The patent applies preliminary action by having the IAB node prepare and notify the UE about the upcoming handover to a new IAB donor before the actual connection switch occurs. The IAB node transmits a handover request message to the UE including cell identifier information, allowing the UE to prepare for reconnection in advance. This preliminary notification mechanism ensures the UE is ready to connect promptly once the IAB node finishes switching to the new donor, eliminating the delay where the UE would otherwise search for base stations after the RLF detection timer expires.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS12581386B2Communication apparatus, control method of communication apparatus, and computer-readable storage medium

Publication Date: 2026.03.17 CANON KK

AI summary

A communication apparatus that functions as a node that relays a link between a user equipment and a base station, comprises: determination unit configured to determine whether or not to switch a base station to which the user equipment is connected via the communication apparatus, from a first base station to a second base station, in a state where the user equipment is RRC (Radio Resource Control)-connected to the first base station via the communication apparatus; and requesting unit configured to, in a case where the determination unit determines that the base station to which the user equipment is connected is to be switched to the second base station, transmit a handover request message that includes information regarding a cell identifier for the second base station, to the user equipment.