SMF Set Registration for Consistent MA-PDU Session Contexts

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Solution Overview

Problem

In 5G networks, the existing procedures for PDU session establishment and deregistration in SMF sets and multi-access scenarios lead to inconsistencies and corruption of binding information due to lack of awareness of SMF sets and unsupported MA-PDU sessions in different PLMNs, resulting in incorrect SMF registration and deregistration contexts in the UDM.

Innovation Solution

Enhancements to the SMF registration and deregistration procedures by including SMF Set IDs in the requests, allowing the UDM to accurately manage and update SMF contexts, ensuring compatibility and correct handling of SMF requests within the same set, even when different SMFs are involved.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the existing PDU session establishment and deregistration procedures are used in SMF sets and multi-access scenarios, then the procedures can be implemented in basic 5G networks, but inconsistencies and corruption of binding information occur due to lack of awareness of SMF sets and unsupported MA-PDU sessions in different PLMNs

Engineering Contradiction:

Improveconsistency of SMF context managementVSAvoidcompatibility with different PLMN versions and SMF set scenarios

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent applies preliminary action by having the SMF perform registration with the UDM before handling PDU session requests. The SMF registers its context including SMF set ID in advance, so that when PDU session establishment or deregistration occurs, the UDM already has the correct binding information and can properly handle requests from any SMF in the set, preventing inconsistencies and corruption.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces the SMF set ID as an intermediary identifier that mediates between multiple SMFs and the UDM. This intermediary allows the UDM to recognize and manage contexts for any SMF belonging to the same set, enabling proper context binding and preventing corruption when different PLMNs or SMFs are involved in MA-PDU sessions.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If SMF contexts are registered without including SMF Set ID, then the registration procedure is simple, but the UDM cannot accurately manage and update SMF contexts when different SMFs are involved in the same set

Engineering Contradiction:

Improvesimplicity of registration procedureVSAvoidbinding information accuracy

Core Design Contradiction:

Ease of operationVSLoss of information

Solution Approach 1:

The patent applies universality by making the SMF set ID a universal identifier that is included in registration requests from any SMF in the set. This single identifier enables the UDM to universally recognize and manage contexts for all SMFs belonging to the same set, maintaining both procedural simplicity and binding information accuracy.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent uses copying by having each SMF in the set register its context with the UDM, where the registration includes a copy of the SMF set ID. This allows the UDM to store multiple SMF contexts with the same set ID, enabling accurate tracking and management of which SMF is associated with which PDU session context.

Inventive Principle:

Principle #26Copying

3Productivity

If the existing deregistration procedure is used without SMF set awareness, then the procedure can be implemented in simple networks, but corruption of binding information occurs when contexts are registered due to requests from different SMFs

Engineering Contradiction:

Improvespeed of deregistration processingVSAvoidintegrity of SMF context binding

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies feedback by having the UDM check the SMF set ID in the deregistration request against the registered context information. The UDM provides feedback by verifying whether the SMF sending the deregistration request belongs to the same set as the registered SMF, and only allows deregistration when the binding is valid, preventing corruption while maintaining efficient processing.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent uses preliminary action by pre-registering the SMF context with the SMF set ID before deregistration occurs. This preliminary registration ensures that when deregistration is requested, the UDM already has the binding information needed to verify the request's validity, enabling both fast processing and reliable integrity checking.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentEP4070591B1Session management function registration and deregistration

Publication Date: 2025.12.24 ZTE CORP

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AI summary

Methods, apparatus and systems for backward compatible multi-access protocol data unit session (PDU) registration and deregistration are described. One method of digital communication includes establishing, by a session management function operating in a communication network, a PDU session for a wireless device and transmitting, upon successfully establishing the PDU session, a registration request to a network-side function to register a context of a PDU session of the wireless device with the network-side function, wherein the registration request identifies a set of session management functions that includes the session management function.