IAB Handover F1 Interface Setup for Inter-CU Migration
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Solution Overview
Problem
Current 3GPP specifications have standardized only intra-CU migration procedures for IAB nodes, leaving a gap in efficient inter-CU migration, particularly in handling the relocation/setup of the F1 connection during handovers, which leads to service interruptions and increased signaling load.
Innovation Solution
Implement CU-triggered F1 setup/relocation procedures during inter-CU IAB migration, where the migrating IAB node's DU is provided with target CU information to initiate the F1-Setup, and the source CU transfers necessary configuration to the target CU for seamless handover.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inter-CU migration procedures are implemented for IAB nodes, then service continuity during handover is improved, but signaling load and complexity increase
Solution Approach 1:
The source CU prepares and transfers F1 configuration information to the target CU before the actual handover occurs. This preliminary action includes generating the F1 configuration information, encapsulating it in a handover request message, and sending it to the target CU, so that when handover occurs, the F1 connection can be rapidly established without extensive signaling exchange.
Solution Approach 2:
The source CU acts as an intermediary by collecting F1 configuration information from the IAB node and transferring it to the target CU. This intermediary role simplifies the handover process by pre-establishing the configuration data that the target CU needs, reducing the signaling burden during the actual handover execution.
2Productivity
If F1 connection setup is performed during IAB handover, then handover speed is improved, but handover time increases
Solution Approach 1:
The F1 configuration information is prepared and transferred in advance during the handover preparation phase. The source CU generates this information and sends it to the target CU before the handover is executed, enabling rapid F1 connection establishment without extending the actual handover execution time.
Solution Approach 2:
The F1 configuration transfer occurs continuously during the handover preparation phase without interrupting normal operations. The source CU maintains its F1 connection with the IAB node while simultaneously preparing and transferring configuration information to the target CU, ensuring uninterrupted service preparation.
Data Source
AI summary
According to some embodiments, a network node is capable of operating as an integrated access and backhaul (IAB) node comprising a distributed unit (DU) and a mobile termination (MT). The IAB node performs a method comprising; obtaining configuration information for establishing an interface between the IAB node DU and a target IAB donor central unit (CU); and after a handover of the IAB node to the target donor, establishing the interface between the IAB node DU and the target IAB donor CU based on the obtained configuration information.