Dual AMF Architecture for Concurrent 5G Network Slice Access
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Solution Overview
Problem
In the 3GPP/5G architecture, user equipment (UE) can only be served by a single Access and Mobility Management Function (AMF) at a time, limiting its ability to concurrently access multiple network slices and services, such as different data network names (DNNs) and session management functions (SMF) sessions.
Innovation Solution
The implementation of a dual AMF approach, where one AMF acts as a Session and Mobility Management-AMF (SM-AMF) for supported network slices and another as a Session Management Only-AMF (SO-AMF) for unsupported slices, allowing concurrent access to multiple network slices by performing distinct roles in session management and mobility management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single AMF serves the UE, then mobility management is simplified and control is centralized, but the UE cannot concurrently access multiple network slices and services
Solution Approach 1:
The AMF function is segmented into two distinct entities: SM-AMF (Session and Mobility Management AMF) that handles mobility management and session management for supported network slices, and SO-AMF (Session Management Only AMF) that handles session management for unsupported network slices. This segmentation allows the UE to concurrently access multiple network slices through different AMF instances, resolving the limitation of single-AMF architectures while maintaining manageable complexity through clear functional separation.
2Adaptability or versatility
If multiple AMFs serve the UE for different network slices, then concurrent access to multiple slices is enabled, but the system complexity and management overhead increase
Solution Approach 1:
The mobility management function is extracted from the SO-AMF and concentrated in the SM-AMF. The SO-AMF is designed to handle only session management for network slices that the SM-AMF does not support. This extraction reduces the complexity of each individual AMF instance while enabling multi-slice access, as the SM-AMF maintains centralized control over mobility while SO-AMFs provide specialized session management capabilities.
Solution Approach 2:
The SM-AMF is designed with multi-functionality to handle both mobility management and session management for supported network slices, while the SO-AMF provides universal session management capabilities for unsupported slices. This multi-functional design allows the system to accommodate diverse network slice requirements without requiring entirely separate AMF instances for each function, thereby reducing overall system complexity.
3Productivity
If the UE is limited to a single AMF, then session management is streamlined, but the ability to access multiple DNNs and SMF sessions is restricted
Solution Approach 1:
Session management is segmented between SM-AMF and SO-AMF based on network slice support. The SM-AMF handles session management for slices it supports, maintaining streamlined processing, while the SO-AMF handles session management for additional slices, enabling multi-DNN and multi-SMF session capabilities. This segmentation allows the system to maintain efficiency for supported slices while expanding capability for unsupported slices.
Data Source
AI summary
A first access and mobility management function (AMF) in a network receives, from user equipment (UE), a registration request listing a first network slice and a second network slice. Upon determining that the first AMF supports the first, but not the second, network slice, the first AMF causes selection of (i) the first AMF as a session and mobility management (SM)-AMF to perform mobility management, and first session management signaling for the first network slice; and (ii) a second AMF as a session management only (SO)-AMF to perform only second session management signaling for the second network slice. The first AMF, acting as SM-AMF, performs the first session management signaling for a first data session on the first network slice, while the second AMF, acting as SO-AMF, performs only the second session management signaling for a second data session on the second network slice.