AMF MA PDU Session Release for 5G ATSSS Support

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Solution Overview

Problem

Existing PDU session establishment in 5G networks is limited to single access networks, making it difficult to support access traffic steering, switching, and splitting (ATSSS) functions, as user traffic cannot be transmitted or received through multiple access networks simultaneously.

Innovation Solution

A method and network entity for converting a multi-access PDU (MA) session into a single-access PDU (SA) session, involving the access and mobility management function (AMF), session management function (SMF), and user plane function (UPF) to manage the release of PDU sessions across different access networks, allowing for the release of specific or all access networks in an MA PDU session.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a single access PDU session is established to one access network, then the session management is simple, but user traffic cannot be transmitted/received through multiple access networks simultaneously

Engineering Contradiction:

Improvemulti-access traffic capabilityVSAvoidsession management complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent segments the multi-access PDU session into multiple single-access PDU sessions, where each access network (3GPP and non-3GPP) has its own dedicated PDU session. This segmentation allows each session to be managed independently with simple session management, while collectively providing multi-access traffic capability through the aggregation of multiple sessions.

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If an MA PDU session is established to support ATSSS function, then user traffic can be transmitted through multiple access networks, but the session release and conversion process becomes complex

Engineering Contradiction:

ImproveATSSS function supportVSAvoidsession release and conversion ease

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

Instead of directly releasing or converting an MA PDU session, the patent inverts the approach by establishing individual SA PDU sessions for each access network. The conversion from MA to SA sessions is achieved by creating separate sessions rather than modifying the existing MA session, simplifying the operation through inversion of the conventional approach.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent introduces the AMF (Access and Mobility Management Function) as an intermediary that coordinates the session management between the UE and the core network. The AMF facilitates the conversion process by managing the establishment and release of individual SA PDU sessions, making the complex ATSSS function support easier to operate through centralized mediation.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of operation

If a PDU session is released through traditional methods, then the release process is simple, but it cannot selectively release specific access networks in an MA PDU session

Engineering Contradiction:

Improveselective access release capabilityVSAvoidrelease message structure

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The patent applies local quality by allowing different release characteristics for different access networks within the same PDU session context. The release request message includes access type information that enables selective release of specific access networks (3GPP or non-3GPP) while maintaining others, providing localized control over session release without requiring complete session termination.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS10893574B2Packet data unit session release method and network entity performing the same

Publication Date: 2021.01.12 ELECTRONICS & TELECOMM RES INST

AI summary

A packet data unit (PDU) session release method and a network entity performing the same are disclosed.An access and mobility management function (AMF) may receive a PDU session release request message including an access type which is an access network to be released in a multi-access PDU (MA PDU) session from user equipment (UE) when the MA PDU session is established. The AMF transmits a first message including the access type to a session management function (SMF).