AMF PDN PDU Session Type Mapping for 5GS EPS Handover
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Solution Overview
Problem
The existing technologies face challenges in handling different Packet Data Network (PDN) and Packet Data Unit (PDU) session types during interworking between Evolved Packet Core (EPC) and 5G Core (5GC), particularly in ensuring seamless session continuity and IP address continuity during handovers.
Innovation Solution
The proposed solution involves an Access and Mobility Management Function (AMF) that facilitates handovers between 5GC and EPC by providing a request for a Session Management (SM) Context that includes mapped EPS Bearer Contexts. This allows the Session Management Function and Packet Data Network Gateway—Control plane (SMF and PGW-C) entity to determine whether to include an EPS Bearer context for non-IP PDN types, ensuring seamless session continuity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the network supports interworking procedures without N26 interface, then IP address continuity can be provided for UEs in both single-registration mode and dual-registration mode, but the complexity of handling different PDN and PDU session type mappings increases
Solution Approach 1:
The patent introduces a mapping mechanism that acts as an intermediary between 5GC PDU session types and EPC PDN types. The AMF and SMF entities perform type mapping and capability discovery, translating between Ethernet/Unstructured PDU types in 5GC and IPv4/IPv6/Non-IP PDN types in EPC, thereby simplifying the interworking complexity while maintaining support for multiple registration modes.
Solution Approach 2:
The patent employs parameter changes by dynamically determining PDN type based on PDU session type and target network capabilities. The system changes the PDN type parameter (IPv4, IPv6, or Non-IP) according to the source PDU session type (Ethernet, Unstructured, or IPv4/IPv6) and the capability indications from the target MME, resolving the mapping complexity through adaptive parameter selection.
2Reliability
If the target MME does not support non-IP PDN type, then compatibility with existing EPC networks is maintained, but seamless session continuity for Ethernet and Unstructured PDU sessions cannot be ensured
Solution Approach 1:
The patent applies preliminary action by performing capability discovery before session establishment or handover. The AMF requests capability information from the target MME regarding non-IP PDN type support, and the SMF determines the appropriate PDN type in advance. This allows the system to prepare alternative IP-based PDN types (IPv4 or IPv6) before handover, ensuring session continuity even when the target MME does not support non-IP PDN types.
Solution Approach 2:
The patent implements dynamics by making the PDN type selection adaptive rather than static. The system dynamically adjusts the PDN type based on real-time capability information from the target MME. If non-IP support is unavailable, the system dynamically switches to IP-based PDN types, thereby maintaining session continuity while adapting to the target network's capabilities.
3Device complexity
If Ethernet and Unstructured PDU session types are mapped to Non-IP PDN type, then session continuity is simplified, but compatibility with MMEs that do not support non-IP PDN type is lost
Solution Approach 1:
The patent uses parameter changes to resolve the mapping issue. Instead of a fixed mapping from Ethernet/Unstructured PDU types to Non-IP PDN type, the system dynamically changes the PDN type parameter based on target MME capability. The mapping becomes: if target MME supports non-IP, then map to Non-IP; otherwise, map to IPv4 or IPv6. This resolves both the complexity and compatibility issues through adaptive parameter selection.
Solution Approach 2:
The patent applies dynamics by making the PDU to PDN type mapping flexible rather than static. The mapping relationship changes dynamically based on the target MME's capability indications. This dynamic mapping ensures both simplified handling when non-IP is supported and broad compatibility when it is not, resolving the contradiction between mapping simplicity and MME compatibility.
Data Source
AI summary
An Access and Mobility Management Function (AMF) adapted for taking part in handover from a 5G system (5GS) to an Evolved Packet System (EPS).