SMF Entity PDU Session Initiation for Broadcast to Unicast Switching

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Solution Overview

Problem

In 5G networks, there is a challenge in quickly initiating a unicast session and establishing a unicast transmission path to switch downlink data from a broadcast path to a unicast path, especially when signal quality is poor, leading to delays and disruptions in service continuity.

Innovation Solution

A method is introduced where the SMF entity actively initiates a PDU session establishment procedure on the network side, ensuring a consistent user plane data path by selecting the same UPF entity for both broadcast and unicast sessions, thereby reducing signaling interactions and delays, and triggering the terminal to establish the PDU session, ensuring fast and continuous data switching.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the terminal initiates a PDU session establishment procedure actively, then the unicast path can be established, but the signaling interaction increases and causes delay

Engineering Contradiction:

Improveservice continuityVSAvoidsession establishment delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

Instead of the terminal actively initiating the PDU session establishment procedure, the network side (SMF entity) actively initiates the procedure by sending a PDU session establishment request message to the terminal. This inversion of the initiation direction reduces signaling interaction and establishment delay while ensuring service continuity.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The network side proactively establishes the PDU session before the terminal needs to switch from broadcast to unicast path. The SMF entity sends the PDU session establishment request in advance, preparing the unicast path beforehand to minimize switching delay and ensure seamless service continuity.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If the network side switches from broadcast path to unicast path, then service continuity is maintained, but the signaling interaction and delay increase

Engineering Contradiction:

Improveservice continuityVSAvoidsignaling interaction complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the session initiation function from the terminal and places it on the network side (SMF entity). This separation allows the network to control the session establishment process, reducing the signaling burden on the terminal and simplifying the overall signaling interaction while maintaining service continuity.

Inventive Principle:

Principle #2Taking out (Extraction)

3Adaptability or versatility

If different UPF entities are selected for broadcast and unicast sessions, then flexibility is improved, but user plane data consistency and synchronization are compromised

Engineering Contradiction:

Improvesession configuration flexibilityVSAvoiduser plane data consistency

Core Design Contradiction:

Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The same UPF entity serves both broadcast and unicast sessions, making it multi-functional. This approach ensures that user plane data remains consistent and synchronized across both transmission modes while still allowing the system to adapt to different service requirements through session configuration.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Reliability

If the terminal switches from broadcast to unicast path, then data transmission reliability is improved, but the switching delay increases

Engineering Contradiction:

Improvedata transmission reliabilityVSAvoidpath switching speed

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The network side initiates the PDU session establishment procedure in advance, preparing the unicast path before the terminal needs to switch from broadcast mode. This preliminary action minimizes the switching delay while ensuring reliable data transmission through the unicast path.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Instead of the terminal initiating the path switch, the network side (SMF entity) initiates the PDU session establishment request, inverting the control direction. This approach accelerates the switching process by eliminating terminal processing delays while maintaining reliable data transmission.

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentEP3745807B1Session establishment method and device

Publication Date: 2023.11.22 HUAWEI TECH CO LTD

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AI summary

This specification provides a session establishment method and device. The method includes: sending, by an SMF entity, a PDU session establishment request message to a terminal, where the PDU session establishment request message is used to request to establish a PDU session; and receiving, by the SMF entity, a PDU session establishment response message from the terminal. A method for actively initiating a PDU session establishment procedure on a network side is provided. When the terminal needs to be switched from a broadcast path to a unicast path, a PDU session may be established for the terminal on the network side, to establish the unicast path. Because it can be ensured that a same UPF entity is selected for the broadcast path and the unicast path on the network side, during switching from a broadcast session to a unicast session, negotiation performed when user plane downlink data is switched from the broadcast path to the unicast path is avoided, so that a delay of switching from the broadcast path to the unicast path can be reduced, to ensure fast switching that meets service continuity requirements in a broadcast mode and a unicast mode. In addition, this can reduce signaling interaction, and further reduce a delay.