PDU Session Deregistration With Automatic Reactivation Signaling

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Solution Overview

Problem

Existing systems lack a method for the Unified Data Management (UDM) or Unified Data Repository (UDR) to initiate the reactivation of a Protocol Data Unit (PDU) session following deregistration due to administrative changes in a wireless device's subscription, such as a change in payment plans, without triggering the Session Management Function (SMF) to perform the necessary deregistration and reactivation.

Innovation Solution

A method and apparatus are provided to enable the UDM and UDR to trigger the deregistration of a PDU session with a reactivation requirement, using commands and flag changes to indicate the need for reactivation, ensuring that the Session Management Function (SMF) is informed to perform the necessary deregistration and subsequent reactivation of the PDU session.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the UDM or UDR initiates deregistration of a PDU session due to administrative reasons (e.g., subscription change), then the deregistration is performed, but the PDU session cannot be reactivated because there is no procedure for reactivation

Engineering Contradiction:
Improvereactivation capabilityVSAvoidprocedure complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by including a reactivation indication flag in the deregistration notification message sent from UDM to SMF. This flag is set in advance to trigger automatic reactivation procedures. When the SMF receives the deregistration notification with the reactivation indication, it automatically initiates reactivation of the PDU session without requiring a separate manual procedure, thus enabling reactivation capability while maintaining procedural simplicity.

Inventive Principle:
Principle #10Preliminary action

2Adaptability or versatility

If a separate reactivation procedure is implemented, then PDU session reactivation is enabled, but the system complexity increases

Engineering Contradiction:
Improvereactivation capabilityVSAvoidoperational simplicity
Core Design Contradiction:
Adaptability or versatilityVSEase of operation

Solution Approach 1:

The patent merges the reactivation indication with the existing deregistration notification message. Instead of creating a separate reactivation procedure or message, the reactivation indication is combined into the deregistration notification that is already being sent from UDM to SMF. This approach enables reactivation capability while avoiding additional operational steps, maintaining ease of operation by utilizing the existing message flow.

Inventive Principle:
Principle #5Merging (Combining)

3Adaptability or versatility

If the UDR is configured to indicate reactivation need, then reactivation can be triggered, but the existing UDR structure must be modified

Engineering Contradiction:
Improvereactivation indicationVSAvoidconfiguration complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by introducing a reactivation indication flag as a new parameter in the deregistration notification message. This flag can be set by the UDM based on subscription change information received from UDR. The existing UDR structure is utilized without major modifications, and the reactivation indication is conveyed through the existing Nudm_UECM_DeregistrationNotification message interface, thus enabling reactivation indication while minimizing configuration complexity.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP4578234B1Deregistration procedure of protocol data unit session
Publication Date: 2026.02.11 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP4578234B1 patent drawingFigure 1
  • EP4578234B1 patent drawingFigure 2
  • EP4578234B1 patent drawingFigure 3

AI summary

Disclosed herein is a method 300 performed by an UDM 104. The method comprises: obtaining s302 a command for triggering deregistration of a network session associated with a SMF, and a UE, wherein the command indicates that reactivation of the network session is required; and after obtaining the command, transmitting s304 towards the SMF a deregistration notification request for triggering the SMF to perform the deregistration of the network session, wherein the deregistration notification request indicates that the network session being deregistered is requested to be reactivated.