Disaster Roaming Search for User Equipment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In disaster scenarios where the core network is damaged but base stations remain operational, user equipment (UE) may not be aware of the service unavailability, leading to prolonged service disruptions due to unsuccessful registration with the Registered PLMN, which cannot provide normal mobile network services.
Innovation Solution
The UE initiates a disaster roaming search upon receiving a System Information Block (SIB) indicating a disaster or availability of disaster roaming, and adjusts its cell selection criteria to register with a second PLMN, including setting a camp threshold to ensure connectivity with a working PLMN.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If UE continues to attempt registration with the Registered PLMN after disaster conditions occur, then the UE maintains connection to the base station, but the service availability deteriorates due to core network damage
Solution Approach 1:
The system performs preliminary actions by detecting disaster conditions through SIB messages before service failure occurs. The network proactively notifies UEs of disaster conditions and provides lists of alternative PLMNs, enabling UEs to switch before attempting registration fails, thus preventing service unavailability rather than recovering from it
Solution Approach 2:
The system implements feedback mechanisms where the network sends SIB messages containing disaster condition information and alternative PLMN lists to UEs. This feedback loop allows UEs to receive real-time information about network status and automatically switch to alternative PLMNs based on the provided guidance, maintaining service availability
2Adaptability or versatility
If UE performs PLMN search and selection procedures, then the UE can find alternative networks, but the service restoration time increases due to unsuccessful registration attempts
Solution Approach 1:
The network provides preliminary information about alternative PLMNs and their suitability for disaster roaming before the UE needs to switch. The SIB messages contain pre-configured lists of alternative PLMNs, allowing UEs to immediately connect to suitable networks without performing extensive search and selection procedures, thus reducing switching time
Solution Approach 2:
The system changes the parameter of PLMN selection by providing prioritized lists of alternative PLMNs with specific selection criteria. Instead of allowing UEs to perform generic PLMN searches, the network directs UEs to specific alternative networks based on disaster conditions, changing the selection parameters from broad search to targeted connection
Data Source
AI summary
A method for disaster roaming includes initiating disaster roaming search by user equipment (UE) if one of following conditions occurs: the UE receives System Information Block (SIB) from a first Public Land Mobile Network (PLMN), the UE receives a message and/or an information element from the first PLMN indicating an occurrence of a disaster or availability of disaster roaming, and the UE determines out-of-service (OOS) from the first PLMN. The SIB includes at least one disaster roaming information element. The method further includes searching by the UE for a second PLMN to register.