ePDG Session Merging for ATSSS Traffic Steering Continuity
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Solution Overview
Problem
Existing 5G networks face challenges in maintaining session service continuity and efficient traffic management when user devices are connected to both cellular and non-cellular networks, such as WLAN, due to differences in SMF and PGW selection across different IP domains.
Innovation Solution
The implementation of an evolved Packet Data Gateway (ePDG) with enhanced functionality to support Access Traffic Steering, Switching, and Splitting (ATSSS) enables the merging of 5G cellular and WLAN sessions into a single registration by relocating the SMF and UPF, using ATSSS trigger messages to facilitate seamless traffic steering and switching between networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate SMF and PGW are used for 5G cellular and WLAN sessions, then network architecture flexibility is improved, but session service continuity deteriorates
Solution Approach 1:
The patent merges the 5G cellular session and WLAN session into a single PDU session by relocating the SMF to anchor both sessions. This combining approach maintains the flexibility of separate network paths while ensuring session continuity through a unified control point, directly resolving the contradiction between architectural flexibility and service continuity.
Solution Approach 2:
The relocated SMF acts as an intermediary that coordinates between the 5G cellular network and WLAN network. It receives ATSSS trigger messages from the UE and manages the session merging process, serving as a mediator that ensures seamless service continuity while preserving the benefits of multi-network architecture.
2Adaptability or versatility
If separate sessions are maintained for 5G cellular and WLAN, then network path diversity is improved, but traffic management efficiency deteriorates
Solution Approach 1:
The patent segments the control plane and user plane functions. The control plane (SMF) is consolidated to manage both sessions efficiently, while the user plane maintains separate paths for 5G cellular and WLAN. This segmentation enables efficient centralized traffic management while preserving network path diversity for flexible data transmission.
Solution Approach 2:
The relocated SMF performs multiple functions by anchoring both 5G cellular and WLAN sessions within a single PDU session. This multi-functionality allows one SMF instance to manage diverse network paths efficiently, improving traffic management productivity while maintaining the ability to utilize different network interfaces.
3Reliability
If ePDG is used for WLAN access, then secure access to untrusted networks is improved, but session merging capability deteriorates
Solution Approach 1:
The patent introduces dynamic session management where the SMF can be relocated based on ATSSS trigger messages from the UE. This dynamic capability allows the system to adapt and merge sessions when needed while maintaining the secure ePDG connection for WLAN access, resolving the contradiction between security and session merging capability.
Data Source
AI summary
Systems and methods described herein enable 5G core session management function (SMF)/user plan function (UPF) relocation to support ATSSS-enabled evolved packet data gateways (ePDG). An ePDG receives an access traffic steering, switching and splitting (ATSSS) trigger message from a user equipment (UE) device. The UE device is connected via a first session using a session management function (SMF) and a via a second session using a packet data network gateway (PGW). The ATSSS trigger message includes an SMF identifier for the SMF. The ePDG sends, in response to the ATSSS trigger message, a request to the SMF to merge the first session and the second session into a single registration.