AMF PDU Session Handover Between Non-3GPP and 3GPP Access
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Solution Overview
Problem
The existing core networks designed for LTE/LTE-A are inadequate to support the advanced requirements of fifth-generation (5G) mobile communications, particularly in terms of multiple numerologies, high reliability, and low latency needed for services like autonomous driving and virtual realities.
Innovation Solution
The proposed solution involves redesigning the core networks to include components such as the Access and mobility Management Function (AMF), Session Management Function (SMF), Policy Control Function (PCF), User Plane Function (UPF), Application Function (AF), Unified Data Management (UDM), and Non-3GPP Interworking Function (N3IWF) to support the new 5G services.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the core network is redesigned to support 5G services with multiple numerologies, high reliability, and low latency, then the network's capability to support advanced services is improved, but the network complexity increases
Solution Approach 1:
The core network is segmented into distinct functional units (AMF, SMF, UPF, PCF, UDM, AF, N3IWF) that can be independently deployed, managed, and scaled. Each function handles specific tasks, allowing the complex 5G network to be broken down into manageable components that can be optimized separately.
Solution Approach 2:
The redesigned core network functions are designed to be multi-functional and adaptable to support various 5G services including autonomous driving and virtual realities. The modular architecture allows the same infrastructure to serve multiple purposes across different service scenarios.
2Reliability
If the PDU session is moved from non-3GPP to 3GPP access, then the service reliability is improved, but the session management complexity increases
Solution Approach 1:
The AMF acts as an intermediary that coordinates the PDU session move between non-3GPP and 3GPP access networks. It manages the interaction between the UE, SMF, and access networks, simplifying the overall session management process while ensuring reliable service continuity during the transition.
Solution Approach 2:
The network performs preliminary actions by establishing the PDU session context in the target 3GPP access before actually moving the session. This includes pre-configuring network resources and preparing the session environment to ensure seamless transition and maintain service reliability.
3Reliability
If resource reservation is performed in the access network for PDU session handover, then the handover success rate is improved, but the resource allocation complexity increases
Solution Approach 1:
The access network performs resource reservation in advance during the PDU session handover preparation phase. By pre-allocating necessary resources before the actual handover occurs, the network ensures that critical services like autonomous driving can switch networks without interruption, improving handover success rates.
Solution Approach 2:
The system implements feedback mechanisms where the SMF and access network continuously monitor resource availability and session status. This feedback loop allows dynamic adjustment of resource allocation during handover processes, ensuring optimal resource utilization while maintaining high handover success rates.
Data Source
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AI summary
In the present specification, provided is an operation method for an access and mobility management function (AMF). The method comprises a step of receiving a session management (SM) context state notification message from a session management function (SMF). The SM context state notification message can be received on the basis of the failure of a protocol data unit (PDU) session establishment procedure. The PDU session establishment procedure can be triggered for a handover of a PDU session between non-3rd generation partnership project (non-3GPP) access and 3GPP access. The method includes a step of updating an access type related to the PDU session on the basis of the SM context state notification message.