IAB Node Group Migration Using Coordinated RRC Reconfiguration
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Solution Overview
Problem
In the R17 IAB system, the migration of an IAB-node to a new donor causes significant wireless link failures and prolonged communication interruptions for downstream child IAB-nodes and UEs due to the need for RRC reestablishment processes.
Innovation Solution
A group migration method and apparatus that involves coordinated RRC reconfiguration and F1 connection management between source and target donor devices, allowing seamless migration of IAB-nodes and their served UEs without RRC reestablishment, thereby maintaining continuous communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an IAB-node migrates to a new donor in the R17 IAB system, then the IAB-node can access new network resources and improve adaptability, but downstream child IAB-nodes and UEs experience wireless link failures and prolonged communication interruptions
Solution Approach 1:
The source donor device performs preliminary actions by determining migration targets for child IAB-nodes before the parent IAB-node completes its migration. Migration target indication information is prepared and included in the handover command, enabling child nodes to proactively establish connections with target donors before parent node migration completes, thus preventing wireless link failures.
Solution Approach 2:
The migration process is segmented into independent phases: parent IAB-node migration and child IAB-node migration. The source donor device independently determines migration targets for child nodes and provides migration target indication information, allowing child nodes to migrate separately from their parent nodes. This segmentation prevents cascading link failures and enables continuous service.
2Adaptability or versatility
If traditional RRC reestablishment process is used during IAB-node migration, then the migration can be completed, but service communication interruption time is prolonged
Solution Approach 1:
The source donor device determines migration targets for child IAB-nodes before the parent IAB-node migration is completed and provides migration target indication information in advance through the handover command. This preliminary action allows child nodes to prepare and execute migration simultaneously with the parent node, avoiding sequential migration delays and reducing overall service interruption time.
Solution Approach 2:
The patent merges the parent IAB-node migration process with child IAB-node migration processes into a coordinated group migration. The source donor device provides migration target indication information that enables child nodes to migrate to target donors in synchronization with the parent node. This combined approach reduces the total migration time compared to traditional sequential RRC reestablishment processes.
Data Source
AI summary
A group migration apparatus, configured in a source donor device, includes a first receiver configured to receive a measurement report transmitted by a migrating IAB (integrated access and backhaul) node, a first transmitter configured to transmit a first migration request message to a target donor device, the first migration request message including context information on the migrating IAB node and its served child IAB-node or UE (user equipment), a second receiver configured to receive a first response message transmitted by the target donor device, the first response message including an RRC (radio resource control) reconfiguration message for the migrating IAB node and its served child IAB-node or UE, and a second transmitter configured to transmit the RRC reconfiguration message to the migrating IAB node and its served child IAB-node or UE.