5G UE EPS Session Management During Network Congestion

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Solution Overview

Problem

In the 5G mobile communication system, the management of control signals during congestion is unclear when the system state changes, particularly in scenarios involving S-NSSAI and DNN combinations, where existing solutions do not effectively manage congestion-related signal control processes.

Innovation Solution

A User Equipment (UE) capable of initiating EPS Session Management procedures without using an Access Point Name (APN) in EPS, and receiving a timer value from a PDU session establishment reject message, enabling effective congestion management across different network slices and APNs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a timer for S-NSSAI and DNN combination congestion control is running, then congestion management is applied, but the UE cannot initiate ESM procedures in EPS

Engineering Contradiction:
Improvecongestion managementVSAvoidsystem flexibility
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent segments the congestion control timer into two independent instances: one timer (T35cd) for S-NSSAI and DNN combination, and another timer (T35ef) for S-NSSAI only. This segmentation allows the UE to initiate ESM procedures in EPS when T35ef is running, while T35cd remains active for 5GS congestion control, thereby resolving the contradiction between maintaining congestion management reliability and enabling system adaptability.

Inventive Principle:
Principle #1Segmentation

2Adaptability or versatility

If the UE initiates ESM procedure with APN in EPS while T35cd is running, then communication continuity is maintained, but congestion control effectiveness is reduced

Engineering Contradiction:
Improvecommunication continuityVSAvoidcongestion control
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent introduces a separate timer T35ef for controlling ESM procedure initiation in EPS based on S-NSSAI, independent from T35cd which controls 5GS PDU session establishment. This allows the UE to initiate ESM procedures in EPS when T35ef is not running, even if T35cd is running, thereby maintaining communication continuity while preserving congestion control effectiveness through the independent T35cd timer.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP3883325B1UE and communication control method
Publication Date: 2024.06.05 SHARP KK
  • EP3883325B1 patent drawingFigure 1
  • EP3883325B1 patent drawingFigure 2
  • EP3883325B1 patent drawingFigure 3

AI summary

Provided is a User Equipment (UE, terminal apparatus) including a transmission and/or reception unit, wherein in a case that a timer for a combination of Single Network Slice Selection Assistance information (S-NSSAI) and no Data Network Name (DNN) is running, the transmission and/or reception unit is capable of initiating an EPS Session Management (ESM) procedure without using an Access Point Name (APN) in an EPS, and the transmission and/or reception unit receives a value of the timer included in a PDU session establishment reject message.