Intermediate SMF Selection for Distributed UPF Session Control

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Solution Overview

Problem

Existing 3GPP specifications assume that the Session Management Function (SMF) covers the entire operator network, failing to address scenarios where SMF cannot control all User Plane Functions (UPFs), particularly in large networks with distributed packet cores and expected mobility across regions.

Innovation Solution

Implementing an intermediate SMF (I-SMF) to control UPFs in specific domains within a PLMN, allowing SMF service areas to be defined based on geographical or administrative areas, with the AMF or NRF assisting in selecting and managing I-SMF entities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If SMF service area covers the entire operator network, then network control coverage is maximized, but device complexity and resource allocation efficiency deteriorate in large distributed networks

Engineering Contradiction:
ImproveSMF service area coverageVSAvoidnetwork complexity
Core Design Contradiction:
Area of stationary objectVSDevice complexity

Solution Approach 1:

The patent divides the SMF service area into multiple domain-specific SMFs, each responsible for specific UPFs in particular geographical or administrative regions. This segmentation allows the network to maintain comprehensive coverage while reducing the complexity burden on individual SMF entities and improving resource allocation efficiency in large distributed networks.

Inventive Principle:
Principle #1Segmentation

2Adaptability or versatility

If distributed packet core is deployed in different regions, then network adaptability and mobility support improve, but the ability of single SMF to control all UPFs deteriorates

Engineering Contradiction:
Improvemobility supportVSAvoidSMF control capability
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent segments the network into multiple domains with domain-specific SMFs that can independently manage UPFs in their respective regions. This enables distributed packet core deployment while maintaining adaptability and mobility support, as each domain SMF can autonomously handle local UPF control without requiring a single SMF to manage all UPFs across the entire network.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces an intermediate SMF entity that acts as a mediator between the core network and domain-specific SMFs. This intermediary SMF receives session management requests, determines the appropriate domain SMF based on UPF location, and coordinates the interaction, thereby enabling distributed architecture while maintaining unified session management control.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Productivity

If intermediate SMF is inserted to control intermediate UPFs, then resource allocation efficiency improves, but device complexity and session management overhead increase

Engineering Contradiction:
Improveresource allocation efficiencyVSAvoidsession management complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent segments session management responsibilities between intermediate SMF and domain-specific SMFs. The intermediate SMF handles high-level session establishment and coordination, while domain-specific SMFs manage local UPF resource allocation. This segmentation improves resource allocation efficiency by enabling localized control while avoiding excessive complexity through clear division of responsibilities.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent enables domain-specific SMFs to autonomously manage their local UPF resources without requiring constant intervention from intermediate or anchor SMFs. Each domain SMF can independently allocate and manage resources within its domain, improving efficiency while reducing overall session management complexity through decentralized autonomous operation.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP3787341B1Method for selecting a session management entity for serving a wireless communication device
Publication Date: 2025.11.26 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP3787341B1 patent drawingFigure 1
  • EP3787341B1 patent drawingFigure 2
  • EP3787341B1 patent drawingFigure 3

AI summary

Disclosed is a method and access management entity for selecting a session management (SM) entity for serving a wireless communication device (WCD) in a core network that comprises an access management entity serving the WCD and an anchor SM entity that controls a first user plane entity that handles a data session associated with the WCD in a first domain, and a second SM entity for controlling a second user plane entity in a second domain of the core network. The method is performed by the access management entity and comprises: selecting - based on WCD information indicating properties of the WCD and based on SM domain information at least indicating the user plane entities that are controlled by the first SM entity and the second SM entity respectively - the second SM entity as an additional intermediate SM entity to control a user plane entity in the second domain for handling the data session in the second domain; sending, towards the second SM entity, a session request message requesting the second SM entity to act as the additional intermediate SM by allocating resources for handling the data session in the second domain; and receiving, in response to the session request message, a session response message indicating that the second SM entity has accepted to act as the additional intermediate SM entity.