AMF SMF Selection Using Service Area Information

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Solution Overview

Problem

Existing wireless communication networks face challenges in managing user equipment sessions when it moves between different service areas, as the serving Session Management Function (SMF) node may not be able to control User Plane Functions (UPFs) in new service areas, necessitating effective SMF selection and reselection mechanisms.

Innovation Solution

The Access and Mobility Management Function (AMF) determines the need for an SMF selection, generates a Network Function discovery request with service area information, and communicates with the Network Function Repository Function (NRF) to receive a list of SMFs, allowing for the selection of an appropriate SMF based on service area information.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single SMF node serves the UE in a specific service area, then session management is simple and reliable in that area, but the SMF cannot control UPFs when the UE moves to different service areas

Engineering Contradiction:

Improvesession management reliabilityVSAvoidservice area coverage

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The network is segmented into multiple service areas, each with its own SMF node. The service area information is segmented and stored in the NF profile, allowing the NRF to provide targeted SMF selections based on the specific service area where the UE is located. This resolves the contradiction by dividing the network into manageable segments that can independently handle local session management while supporting mobility across areas.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Service area information is preliminarily included in the NF profile during SMF registration with the NRF. This preliminary action enables the NRF to proactively provide appropriate SMF selections based on the target service area before the UE actually moves there, ensuring seamless session management during mobility without requiring complex real-time decisions.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If SMF selection is performed without service area information, then the selection process is simple and fast, but the selected SMF may not be able to control UPFs in the new service area

Engineering Contradiction:

ImproveSMF selection speedVSAvoidUPF control capability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The AMF provides feedback to the NRF about the target service area where the UE is moving. The NRF uses this feedback to select an SMF that has the capability to control UPFs in that specific service area. This feedback mechanism ensures that the selected SMF is both geographically appropriate and capable of maintaining session continuity.

Inventive Principle:

Principle #23Feedback

3Adaptability or versatility

If service area information is included in NF discovery requests and responses, then appropriate SMF selection is enabled, but the signaling overhead and processing complexity increase

Engineering Contradiction:

Improveservice area-based SMF selectionVSAvoidNF discovery processing complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

Service area information is included locally in the NF profile of each SMF registered with the NRF. This local quality approach allows the NRF to efficiently query and match SMFs based on the target service area without requiring complex global analysis. The information is stored in a structured, easily accessible format that simplifies the discovery process.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The service area information in the NF profile serves multiple functions: it enables SMF selection, supports mobility management, and provides geographic context for session continuity. This multi-functionality reduces the need for separate mechanisms, thereby reducing overall system complexity despite the added information element.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS12483975B2Session management function service area information provision

Publication Date: 2025.11.25 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

An Access and Mobility Management Function (“AMF”) can include processing circuitry and memory coupled to the processing circuitry. The memory has instructions stored therein that are executable by the processing circuitry to cause the AMF to perform operations. The operations include determining that selection of a Session Management Function (“SMF”) from a plurality of SMFs of a communications system is needed. The operations further include, responsive to the determination, generating a network function (“NF”) discovery request including a service area indication requesting service area information for discovered SMFs. The operations further include communicating the NF discovery request toward a NF Repository Function (“NRF”). The operations further include receiving a NF discovery response including SMF identifiers and service area information for a list of SMFs. The operations further include selecting the SMF from the list of SMFs.