Inter-RAT Handover in 5G Networks with Separated AMF and SMF
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Solution Overview
Problem
In 5G networks with separated control and user plane functions, inter-system handovers between 5G and 4G networks face challenges in ensuring data continuity due to the separation of AMF and SMF entities, which complicates the handover process and service continuity.
Innovation Solution
A network handover method is introduced where a source radio access network node sends a handover request to a source mobility management function entity with a target base station identifier, triggering inter-system handover, and involving session and mobility management contexts to ensure successful handover and data service continuity, even with separated control and user plane functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If control plane and user plane functions are separated in 5G network, then network flexibility and service customization are improved, but handover process complexity and data continuity assurance difficulty increase
Solution Approach 1:
The patent segments the control plane functions into separate AMF (Access and Mobility Management Function) and SMF (Session Management Function) entities. During handover, the AMF handles mobility management while the SMF handles session management, allowing independent optimization of each function and reducing overall system complexity despite the separation.
Solution Approach 2:
The patent introduces a target MME (Mobility Management Entity) as an intermediary during inter-system handover between 5G and 4G networks. The target MME receives handover requests from the source gNB, coordinates with both AMF and SMF entities, and manages the transfer of user plane data, simplifying the complex interactions between separated control and user plane functions.
2Adaptability or versatility
If AMF and SMF entities are separated, then network function flexibility is improved, but handover execution difficulty and service continuity assurance increase
Solution Approach 1:
The patent performs preliminary actions during handover preparation by having the target MME establish data transmission channels with both the AMF and SMF before the actual handover occurs. The target MME receives session management context from the source MME and pre-configures the user plane data transmission path, ensuring service continuity is maintained during the handover execution phase.
Solution Approach 2:
The patent implements feedback mechanisms where the target MME receives handover confirmations from the target gNB and sends relocation confirmations back to the source AMF. This feedback loop ensures that all network entities are synchronized about the handover status, allowing for proper resource allocation and maintaining service continuity throughout the handover process.
Data Source
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AI summary
Embodiments of this application provide a network handover method and a related device. The method includes: when receiving a user terminal handover request that is sent by a source radio access network node and that carries a target base station identifier, determining, by a source mobility management function entity based on the target base station identifier, to trigger inter-RAT network handover; sending a first message to a source session management function entity; receiving a second message sent by the source session management function entity, where the second message includes a session management context; and sending a relocation request to a target mobility management function entity, where the relocation request is used to instruct the target mobility management function entity to perform inter-RAT network handover on the user terminal. In this way, data continuity in an inter-RAT network handover process is ensured.