DU Inter-CU Handover via F1 Interface Pre-Establishment
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Solution Overview
Problem
The existing technologies lack a complete solution for handing over a distributed unit (DU) between central units (CUs) under a CU-DU separated network architecture, particularly in scenarios involving low earth orbit satellites and 5G/6G mobile communication with integrated access and backhaul technology.
Innovation Solution
A handover method and device that enables a DU to determine the need for an inter-CU handover, initiate an F1 interface establishment request to a target CU, and transfer to the target CU upon receiving a response, involving the source CU in the process to ensure seamless handover.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a DU is deployed in moving platforms (trains, airplanes, ships) to provide network services, then network deployment flexibility is improved, but handover management complexity increases due to the need for inter-CU handover
Solution Approach 1:
The handover process is segmented into distinct phases: F1 interface establishment phase (DU to target CU), instruction transmission phase (DU to source CU), and execution phase (actual handover). This segmentation allows each phase to be managed independently, reducing overall complexity while maintaining flexibility for mobile DU deployments
Solution Approach 2:
The F1 interface establishment request is sent in advance before the actual handover execution. The DU proactively establishes the F1 interface with the target CU and obtains handover instructions before the handover is fully executed, ensuring seamless transition while managing complexity through advance preparation
2Reliability
If inter-CU handover procedures are implemented for mobile DUs, then service continuity is improved, but signaling overhead increases due to multiple message exchanges
Solution Approach 1:
Multiple handover-related messages are merged into consolidated exchanges. The F1 interface establishment request carries multiple pieces of information (handover indication, target CU identification) in a single message, and the handover instruction message combines multiple control elements, reducing the total number of signaling messages while ensuring service continuity
Solution Approach 2:
The F1 interface establishment request message serves multiple functions: it establishes the F1 interface, indicates the handover intent, and provides target CU identification. This multi-functionality reduces signaling overhead by eliminating the need for separate messages for each function, while maintaining reliable service continuity through the handover process
Data Source
AI summary
Disclosed are a handover method and device. In embodiments of the present application, first, a DU determines that an inter-CU handover is required and then sends an F1 interface establishment request to a target CU, the F1 interface establishment request indicating that the reason for the establishment is the inter-CU handover for the DU; upon receiving the F1 interface establishment request sent from the DU, the target CU returns an F1 interface establishment response to the DU; upon receiving the F1 interface establishment response returned by the target CU, the DU sends to a source CU a message for instructing the DU to perform the inter-CU handover; and then, the DU is handed over from the source CU to the target CU.