Serving NF Subscription Restoration for Persistent UE Event Exposure

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Solution Overview

Problem

Existing 5G Core Network architectures face challenges in maintaining subscriptions for network analytics services due to UE deregistration, PDU session changes, and NF reallocation, leading to loss of event notifications and inaccurate analytics reports.

Innovation Solution

A method for maintaining subscriptions by generating and storing subscription restoration information in a data storage function, which is retrievable by subsequent NF instances to restore subscriptions upon UE reconnection or NF reallocation, ensuring continuous event data collection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the NWDAF subscribes to event exposure services at serving NFs to collect user data continuously, then analytics reports can be generated, but subscriptions are lost when UEs move, deregister, or when NFs are reallocated

Engineering Contradiction:

Improvesubscription maintenanceVSAvoidsubscription context loss

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The patent applies preliminary action by storing subscription restoration information in advance in a persistent manner. When a subscription is established, the serving NF stores the subscription context and restoration information proactively, so that if the UE moves or deregisters, the subscription can be restored without loss. This prevents the subscription context loss that would otherwise occur during UE mobility or NF reallocation scenarios.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary mechanism where subscription restoration information is stored in a persistent storage function (such as UDM or UDR) that acts as a mediator between the serving NF and the NWDAF. This intermediary storage ensures that subscription context is preserved even when the serving NF changes due to UE mobility or reallocation, allowing the new serving NF to retrieve and restore the subscription.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If the UE moves or deregisters from the network, then network mobility is supported, but event subscriptions are lost and data collection stops

Engineering Contradiction:

ImproveUE mobility supportVSAvoidsubscription duration

Core Design Contradiction:

Adaptability or versatilityVSDuration of action of stationary object

Solution Approach 1:

The patent applies preliminary action by pre-storing subscription restoration information in persistent storage before UE mobility or deregistration occurs. This allows the subscription to be restored automatically when the UE re-attaches or is reallocated, maintaining continuous data collection despite the UE's movement or temporary disconnection from the network.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent ensures continuity of useful action by implementing a mechanism where subscription context is preserved and can be restored. The persistent storage of subscription restoration information ensures that data collection continues uninterrupted even during UE mobility events, as the new serving NF can retrieve and reactivate the subscription, maintaining continuous monitoring and analytics.

Inventive Principle:

Principle #20Continuity of useful action

3Productivity

If NFs are reassigned due to UE mobility to closer NFs, then network efficiency is improved, but existing subscriptions are lost

Engineering Contradiction:

Improvenetwork efficiencyVSAvoidsubscription persistence

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent introduces an intermediary persistent storage function (UDM/UDR) that mediates between the old and new serving NFs during NF reallocation. When NFs are reassigned due to UE mobility, the new serving NF retrieves subscription restoration information from this intermediary storage, ensuring subscription persistence is maintained while allowing the network efficiency benefits of NF reassignment to be realized.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent applies preliminary action by storing subscription context and restoration information in persistent storage before NF reallocation occurs. This allows the new serving NF to quickly restore subscriptions after taking over UE service, maintaining both network efficiency through NF reassignment and subscription reliability through pre-prepared restoration information.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS12621788B2Technique for maintaining a subscription of a subscriber NF

Publication Date: 2026.05.05 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

A technique for maintaining a subscription of a subscriber Network Function, NF, for receiving events related to a User Equipment, UE, from a serving NF in a telecommunication system is disclosed, wherein the UE is served by a first instance of the serving NF. A method implementation of the technique is performed by the first instance of the serving NF and comprises receiving (S502) a subscription request from the subscriber NF, the subscription request including a persistence indication indicating that the subscription is to be maintained, triggering (S504) generating subscription restoration information enabling restoration of the subscription in case the first instance of the serving NF ceases serving the UE, and triggering (S506) storing the subscription restoration information in a data storage function of the telecommunication system in association with the UE, wherein the subscription restoration information is to be used by a second instance of the serving NF for restoring the subscription if the first instance of the serving NF ceases serving the UE.