PDN Connection Termination for 2G to 5G Mobility

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Solution Overview

Problem

The transition of User Equipment (UE) mobility from a 2G/3G network to a 5G network via a 4G network is not seamless, often resulting in session breaks and increased network load, as existing systems do not effectively handle direct mobility between 5G and 2G/3G networks, leading to call drops during handovers.

Innovation Solution

A method is introduced where network nodes trigger the termination of Packet Data Network (PDN) connections when a UE moves from a 2G/3G network to a 4G network, forcing reconnection before transitioning to a 5G network, using common network entities that support interworking between 4G and 5G networks, such as an SMF+PGW-C, to ensure seamless mobility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If UE moves directly from 2G/3G network to 5G network, then mobility speed is improved, but session continuity deteriorates causing call drops

Engineering Contradiction:

Improvemobility speedVSAvoidsession continuity

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The patent applies preliminary action by triggering the termination of PDN connections when the UE moves from 2G/3G to 4G network, forcing the UE to reestablish connectivity before transitioning to 5G. This preparatory action ensures that the UE is properly prepared for seamless handover to 5G, preventing session breaks and call drops during the transition.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If UE reestablishes connectivity through 4G network before 5G, then session continuity is improved, but network load increases

Engineering Contradiction:

Improvesession continuityVSAvoidnetwork load

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The network node triggers termination of PDN connections at the appropriate moment (when UE moves from 2G/3G to 4G), which is a preliminary action that prepares the UE for seamless 5G handover. This timing optimization ensures reestablishment happens only when necessary, minimizing unnecessary network load while maintaining session continuity.

Inventive Principle:

Principle #10Preliminary action

3Adaptability or versatility

If legacy PGW is used for IMS APN, then backward compatibility is improved, but mobility to 5G deteriorates causing session breaks

Engineering Contradiction:

Improvebackward compatibilityVSAvoidmobility to 5G

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies preliminary action by triggering PDN connection termination when the UE moves from 2G/3G to 4G network. This ensures that when the UE subsequently moves to 5G network, the reestablished connectivity uses appropriate 5G-capable network entities (such as SMF+PGW-C) that support both IMS APN and seamless mobility, thereby maintaining backward compatibility while enabling reliable 5G mobility.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS11470528B2Technique for preparing user equipment mobility

Publication Date: 2022.10.11 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

A technique for preparing User Equipment, UE, mobility from a 4G network to a 5G network for a UE moving from a 2G/3G network to the 5G network via the 4G network is disclosed. A method implementation of the technique is performed by a network node and comprises triggering terminating one or more Packet Data Network, PDN, connections associated with the UE when the UE moves from the 2G/3G network to the 4G network forcing the UE to reestablish connectivity with the 4G network prior to moving from the 4G network to the 5G network.