5G Core TDF Integration Through PCF and Split Control Planes

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Solution Overview

Problem

In the 5G network architecture, the Traffic Detection Function (TDF) lacks integration with the core network, necessitating the absence of essential information from the Policy Control Function (PCF) for its operations, which is outside the 3GPP scope.

Innovation Solution

Integrate the Traffic Detection Function (TDF) with the core network by extending the Policy Control Function (PCF) with a service (Npcf_TDFPolicyControl) to allow retrieval of subscriber session information and Application Detection and Control (ADC) rules, and split TDF functionality into a control plane function (TDF-C) and user plane function (TDF-U), integrating TDF-U with the Session Management Function (SMF) through an Nsmf_TDFN4 service.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the TDF is deployed outside the 3GPP core network scope, then it maintains architectural independence, but it cannot receive necessary subscriber session information and ADC rules from the PCF

Engineering Contradiction:

ImproveTDF integration capabilityVSAvoidSubscriber session information and ADC rules

Core Design Contradiction:

Adaptability or versatilityVSLoss of information

Solution Approach 1:

The patent introduces the PCF as an intermediary between the TDF and the 5G core network. The PCF receives subscriber session information from the SMF and ADC rules from the AF, then forwards this information to the TDF through a service-based interface, enabling the TDF to obtain necessary data without direct integration into the core network.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent segments the TDF functionality into control plane functions (TDF-C) and user plane functions (TDF-U), with the TDF-C interacting with the PCF for control information and the TDF-U handling user plane traffic. This segmentation allows different parts of the TDF to obtain information through appropriate interfaces.

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If the TDF is split into control plane function (TDF-C) and user plane function (TDF-U), then it achieves functional separation and flexibility, but it increases system complexity and requires additional reference points

Engineering Contradiction:

ImproveControl user plane separationVSAvoidSystem architecture complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent divides the TDF into two separate functional entities: TDF-C for control plane operations (receiving ADC rules from PCF, generating PCC rules) and TDF-U for user plane operations (packet inspection, traffic detection). This segmentation enables independent deployment and operation of control and user plane functions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent designs the TDF-C and TDF-U to work with multiple reference points and service interfaces, allowing them to serve different functions: TDF-C interfaces with PCF for policy control, TDF-U interfaces with UPF for user plane traffic handling, and both can interact with AF for application detection. This multi-functionality reduces the need for separate specialized components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If the TDF requires information from PCF for its operations, then it can perform application detection and control functions, but it creates dependency on PCF which is outside traditional TDF scope

Engineering Contradiction:

ImproveTDF operational reliabilityVSAvoidInter-function dependency

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The PCF serves as a mediator that collects information from multiple sources (SMF for subscriber session information, AF for application detection rules) and consolidates this information for the TDF. This intermediary approach allows the TDF to obtain comprehensive information without establishing direct complex connections to multiple network functions.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The PCF performs preliminary actions by pre-processing and consolidating subscriber session information and ADC rules before forwarding them to the TDF. This preliminary preparation reduces the information processing burden on the TDF and ensures that the TDF receives ready-to-use configuration data.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentEP4035309B1Communications network architecture

Publication Date: 2025.08.27 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

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AI summary

A Policy Control Function, PCF, for use in a 5G core network, is configured to allow a consumer to retrieve from the PCF subscriber session information and Application Detection and Control rules relating to a subscriber session. Specifically, the PCF is configured to: receive (303) a request from a Session Management Function, SMF, for session management policies applying to the subscriber session; retrieve (305) policy data from a Unified Data Repository, UDR; and, based on the retrieved policy data, generate said Application Detection and Control rules relating to the subscriber session, and send (307) said Application Detection and Control rules to the TDF, thereby allowing the TDF to act as the consumer.