AMF Context Transfer via NG-RAN for Disjoint Network Slices
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Solution Overview
Problem
In 5G networks, users subscribed to multiple network slices cannot simultaneously use services from disjoint networks due to communication barriers between Access and Mobility Management Functions (AMFs), leading to signaling delays and service activation issues when switching between different network slices.
Innovation Solution
The solution involves a new AMF fetching UE contexts from an old AMF via the NG-RAN, using a Namf_Communication_UEContextTransfer request message to facilitate registration and manage disjoint network identifiers, enabling seamless transitions between disjoint network slices without direct communication between AMFs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a UE switches between services from multiple disjoint networks, then service versatility is improved, but signaling delay increases and service activation becomes complex
Solution Approach 1:
The patent applies preliminary action by pre-fetching UE context information from the old AMF to the new AMF before the UE actually switches network slices. The new AMF proactively retrieves subscription data, security contexts, and PDU session information in advance, so that when service activation is needed, the context is already available, eliminating signaling delays during the switch.
Solution Approach 2:
The patent introduces an intermediary mechanism where the NG-RAN acts as a mediator to facilitate context transfer between disjoint AMFs. The NG-RAN receives context transfer requests, forwards them to the appropriate old AMF, and relays responses to the new AMF, enabling communication between AMFs that would otherwise be isolated, thus reducing signaling delays while maintaining network slice isolation.
2Productivity
If direct communication between disjoint AMFs is established, then service activation speed is improved, but network complexity increases
Solution Approach 1:
The patent uses NG-RAN as an intermediary to enable communication between disjoint AMFs without creating direct AMF-to-AMF connections. This approach achieves fast service activation by allowing context transfer requests to flow through the NG-RAN, while avoiding the complexity of establishing direct communication paths between multiple AMFs in the core network.
Solution Approach 2:
The patent segments the context transfer function into separate components: the new AMF initiates the transfer, the NG-RAN handles the routing and forwarding, and the old AMF provides the context. This segmentation allows each component to perform its function independently without requiring complex inter-AMF communication infrastructure, thus improving activation speed while controlling network complexity.
3Reliability
If UE context is transferred between disjoint AMFs via NG-RAN, then service continuity is improved, but signaling overhead increases
Solution Approach 1:
The patent merges multiple signaling operations into a single context transfer procedure. Instead of separately transferring UE identity, subscription data, security contexts, and PDU session information through multiple individual messages, the system combines these into one comprehensive Namf_Communication_UEContextTransfer request-response exchange, reducing signaling overhead while ensuring service continuity.
Solution Approach 2:
The patent uses copying by creating a complete replica of the UE context from the old AMF and transferring it to the new AMF. This copy includes all necessary information (subscription data, security parameters, PDU session states) in a single transfer operation, ensuring service continuity without requiring multiple back-and-forth signaling exchanges to retrieve individual context elements.
Data Source
AI summary
Disclosed are techniques for registering a user equipment (UE) to a new access and mobility management function (AMF). When a new access and mobility management function (AMF) determines that an old AMF is disjoint AMF i.e. they are not connected, then the new AMF fetches the UE context (5GMM and SGSM context) from the old AMF via new generation radio access network (NG-RAN). The new AMF routes a Namf_Communication_UEContextTransfer request message to the old AMF to fetch the UE contexts via NG-RAN. The old AMF sends the UE contexts in the Namf_Communication_UEContextTransfer response message to the new AMF via NG-RAN. Based on the context transfers between the new AMF and the old AMF, the UE is registered to the new AMF.