HPLMN Traffic Control for Cross-PLMN MA PDU Sessions

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Solution Overview

Problem

Existing 5G communication systems fail to support Access Traffic Steering, Switching, and Splitting (ATSSS) features when user equipment (UE) is registered on different Public Land Mobile Networks (PLMNs, leading to terminated MA PDU sessions and high roaming charges for data services.

Innovation Solution

Implement a method and system for Home Public Land Mobile Network (HPLMN)-based traffic control by establishing a Multi-Access PDU (MA PDU) session with UE registered on different PLMNs, involving the HPLMN determining and sending an ATSSS policy to manage traffic flow, using interfaces like N11 and N16 to extend ATSSS features.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the UE is registered on different PLMNs for 3GPP and non-3GPP access, then mobility and access flexibility are improved, but the MA PDU session is terminated and ATSSS feature cannot be supported

Engineering Contradiction:

Improveaccess flexibilityVSAvoidMA PDU session continuity

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent segments the session management by introducing separate session management functions for HPLMN and VPLMN. The HPLMN SMF maintains the MA PDU session context while the VPLMN provides access mobility, allowing the session to be preserved across different PLMN registrations. This segmentation resolves the contradiction by decoupling session continuity from access network registration.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces an intermediary mechanism where the HPLMN SMF acts as a mediator that receives session establishment requests from the VPLMN and manages the MA PDU session context. This intermediary enables the MA PDU session to be maintained across different PLMNs by establishing a coordinated management relationship between HPLMN and VPLMN session management functions.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If the UE is registered on a VPLMN for 3GPP access, then roaming capability is improved, but traffic control by HPLMN is lost and roaming charges increase

Engineering Contradiction:

Improveroaming capabilityVSAvoidroaming charges

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The HPLMN SMF acts as an intermediary that receives session establishment requests from the VPLMN and establishes the MA PDU session under HPLMN control. This allows the HPLMN to maintain traffic control policies and route traffic through home network data services, thereby reducing roaming charges while preserving roaming capability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

Instead of the VPLMN controlling traffic when the UE is registered on it, the patent inverts the control relationship by having the HPLMN SMF receive requests from VPLMN and maintain session control. This inversion enables the HPLMN to continue controlling traffic routing and policy enforcement even when the UE is registered on a visited network.

Inventive Principle:

Principle #13The other way round (Inversion)

3Device complexity

If the MA PDU session is established only when UE is registered to the same VPLMN for both 3GPP and non-3GPP access, then session management simplicity is improved, but ATSSS feature extendability is reduced

Engineering Contradiction:

Improvesession management complexityVSAvoidATSSS feature extendability

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent segments the session management architecture into HPLMN SMF and VPLMN SMF functions with clearly defined interfaces. The HPLMN SMF manages the MA PDU session context while the VPLMN SMF handles access-specific procedures. This segmentation allows ATSSS features to be extended to different-PLMN scenarios while maintaining manageable complexity through defined responsibility boundaries.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent creates a universal session management mechanism where the HPLMN SMF can serve both home-registered and roaming UEs through a standardized interface with VPLMN SMF. This multi-functional approach allows the same session management framework to handle both same-PLMN and different-PLMN scenarios, extending ATSSS feature applicability without proportionally increasing complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentEP4145949B1Method and system for hplmn-based traffic control when UE is registered on different plmns

Publication Date: 2025.07.30 SAMSUNG ELECTRONICS CO LTD

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AI summary

The present disclosure relates to a communication method and system for converging a 5th-Generation (5G) communication system for supporting higher data rates beyond a 4th-Generation (4G) system with a technology for Internet of Things (IoT). The present disclosure may be applied to intelligent services based on the 5G communication technology and the IoT-related technology, such as smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, security and safety services. Embodiments herein provide a method for establishing a multi-access protocol data unit (MA PDU) session of a user equipment (UE) by a home public land mobile network (HPLMN) in a wireless communication network.