5G to EPS Handover PDU Session Continuity

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

In the transition from 5GS to EPS, PDU sessions without User Plane (UP) are deleted, leading to service disruptions, particularly affecting IMS services, as existing technologies do not support selective UP activation and deactivation, resulting in re-establishment of sessions from scratch.

Innovation Solution

A method and apparatus for inter-system handover from 5GS to EPS, where the Access and Mobility Management Function (AMF) allocates and sets up UP resources for all PDU sessions, including those without initial UP, ensuring seamless continuity and selective UP management.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If selective UP activation and deactivation is implemented in 5GS, then resource efficiency is improved, but PDU sessions without UP are deleted during handover to EPS, causing service disruptions

Engineering Contradiction:

Improveresource efficiencyVSAvoidservice continuity

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The AMF performs preliminary actions by allocating and setting up UP resources for all PDU sessions during the handover preparation phase, before the actual handover occurs. This includes proactively establishing UP resources for PDU sessions that did not have UP activated in 5GS, ensuring that all sessions are ready for seamless transition to EPS without service disruption.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If all PDU sessions maintain UP connection in 5GS, then service continuity is improved, but resource consumption increases

Engineering Contradiction:

Improveservice continuityVSAvoidresource consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The system dynamically manages UP resources based on handover requirements. During normal operation in 5GS, UP resources are activated only when needed (selective activation). During handover to EPS, the system dynamically allocates and activates UP resources for all PDU sessions that require them, ensuring service continuity while avoiding unnecessary resource consumption during stationary phases.

Inventive Principle:

Principle #15Dynamics

3Device complexity

If PDU sessions without UP are deleted during handover, then handover simplicity is improved, but service disruption occurs requiring re-establishment from scratch

Engineering Contradiction:

Improvehandover simplicityVSAvoidservice restoration time

Core Design Contradiction:

Device complexityVSLoss of time

Solution Approach 1:

The AMF performs preliminary allocation and setup of UP resources for all PDU sessions during the handover preparation phase, before the handover is executed. This preliminary action ensures that when the handover occurs, all PDU sessions including those without initial UP have their resources already prepared, eliminating service disruption and avoiding the need for time-consuming re-establishment procedures.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS12075305B2User plane setup during 5G system to evolved packet system handover

Publication Date: 2024.08.27 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

System comprising a mobility management entity, MME, a first Radio Access node, RAN (eNB) offering Long Term Evolution, LTE, access, and a second radio access node, RAN (gNB) offering New Radio, NR, access; a user entity, UE, supporting both Long Term Evolution, LTE, and New Radio, NR, Radio Access Technology, RAT.