Disaster Roaming PLMN Selection for UE Service Continuity

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Solution Overview

Problem

The current Fifth Generation (5G) system lacks mechanisms for notifying User Equipments (UEs) about disaster conditions in a Public Land Mobile Network (PLMN) and enabling them to switch to alternative PLMNs for service continuity.

Innovation Solution

A method for UEs to determine a disaster condition in their PLMN by checking for unavailable cells, broadcast messages, or failed registration/service requests, and receive a 'disaster roaming PLMN list' from another PLMN to switch to an alternative PLMN for service.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the current 5G system operates without disaster notification mechanisms, then the system structure remains simple, but service continuity is lost during disaster conditions

Engineering Contradiction:

Improveservice continuityVSAvoidsystem structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The system performs preliminary actions by broadcasting disaster roaming PLMN lists before disasters occur and maintaining updated lists of alternative PLMNs that can accept disaster inbound roamers. This advance preparation enables UEs to quickly switch to alternative networks when disasters strike, ensuring service continuity without requiring complex real-time decision-making during emergencies

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary mechanism through the disaster roaming PLMN list that mediates between the home PLMN and alternative PLMNs. This list acts as a pre-established communication bridge, allowing UEs to seamlessly transition to alternative networks during disasters without direct complex interactions between multiple network entities

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If UEs are allowed to roam to any alternative PLMN during disasters, then service availability improves, but network security and control deteriorate

Engineering Contradiction:

Improveservice availabilityVSAvoidnetwork control

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

Alternative PLMNs perform preliminary actions by pre-configuring their acceptance policies for disaster inbound roamers and broadcasting their PLMN identifiers in the disaster roaming PLMN list. This advance configuration allows UEs to connect during disasters while maintaining network control, as alternative PLMNs are already prepared to authenticate and manage disaster roaming sessions

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent applies local quality by enabling disaster roaming functionality selectively in alternative PLMNs that have explicitly indicated their willingness to accept disaster inbound roamers. Not all PLMNs participate in disaster roaming, and each alternative PLMN maintains its own local policies and control mechanisms, allowing service availability to improve in participating networks while maintaining security through localized decision-making

Inventive Principle:

Principle #3Local quality

3Reliability

If the system implements comprehensive disaster notification and alternative PLMN selection, then UE service continuity improves, but information management complexity increases

Engineering Contradiction:

ImproveUE service continuityVSAvoidinformation management

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The patent segments information management by dividing the disaster roaming process into distinct components: the disaster roaming PLMN list (maintained by UEs), the alternative PLMN acceptance indicators (broadcast by alternative PLMNs), and the home PLMN status information. This segmentation allows each component to be managed independently, reducing overall information management complexity while ensuring comprehensive disaster notification and alternative PLMN selection

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent extracts critical disaster roaming information (alternative PLMN identifiers and acceptance status) from the complex network environment and consolidates it into the compact disaster roaming PLMN list. This extracted list contains only the essential information needed for disaster roaming decisions, separating critical data from unnecessary information and simplifying UE processing during emergencies

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS12556902B2Notification of disaster condition and alternative PLMNs

Publication Date: 2026.02.17 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

Systems and methods for enabling notification of disaster conditions and alternative Public Land Mobile Networks (PLMNs) to network nodes are disclosed. In one embodiment, a method performed by a User Equipment (UE) for responding to a disaster condition in a first PLMN, comprises determining that a first PLMN is not available; determining that a second PLMN is available for disaster roaming; and attempting to register with the second PLMN, responsive to determining that the first PLMN is not available due to the disaster condition and determining that a second PLMN is available for disaster roaming. In this way, a UE is informed of the failure of its currently used PLMN due to a disaster condition and a service may be provided in another PLMN, where the UE under normal conditions may not be allowed to receive a service from the second PLMN.