Satellite Emergency Alerts for UE Reception Without Terrestrial Coverage
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Solution Overview
Problem
User equipment (UE) is unable to receive wireless emergency alerts when terrestrial coverage is not available and is not subscribed to a satellite service.
Innovation Solution
UE initiates a radio access technology (RAT) scan to identify an emergency alert (EA) PLMN provided by a satellite service, passively monitors the EA PLMN for a System Information Block 12 (SIB12) broadcast message, and provides the emergency alert upon reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If UE performs RAT scan to identify available PLMN, then terrestrial network coverage is detected, but emergency alert reception is not possible without terrestrial coverage
Solution Approach 1:
The UE is configured to perform both terrestrial PLMN scanning and satellite EA PLMN scanning using the same radio frequency interface. When terrestrial coverage is unavailable, the UE automatically transitions to scanning for satellite-provided EA PLMNs, allowing the device to universally access emergency alert services across both terrestrial and non-terrestrial coverage areas without requiring separate hardware systems.
2Reliability
If UE is not subscribed to satellite service, then terrestrial service restrictions apply, but emergency alert reception via satellite is blocked
Solution Approach 1:
The emergency alert reception capability is extracted from the satellite service subscription requirement. The UE scans specifically for EA PLMNs and can receive emergency alerts from satellite networks without needing a full satellite service subscription. This separates the emergency alert function from the broader satellite service, allowing unrestricted access to critical emergency information while maintaining service provider control over other satellite features.
3Reliability
If UE passively monitors EA PLMN for SIB12 message, then emergency alert is received, but time and energy are consumed during monitoring
Solution Approach 1:
The UE implements periodic scanning of EA PLMNs rather than continuous monitoring. The device performs RAT scan cycles at defined intervals, checking for available EA PLMNs and their SIB12 emergency alert messages only when needed. This periodic approach reduces energy consumption compared to continuous monitoring while ensuring timely detection of emergency alerts, as the UE can quickly scan and identify alert messages during each scan cycle.
Data Source
AI summary
Systems and methods are provided for providing wireless emergency alerts (e.g., weather alerts, missing persons alerts, earthquake alerts, etc.) to UEs even when terrestrial coverage is not available. For example, a UE typically performs a RAT scan to identify an available PLMN. In some aspects, the UE is capable of receiving satellite signals but is not subscribed to a satellite service. If the RAT cycle completes without identifying an available PLMN, the UE begins searching for an EA PLMN provided by a satellite service. Upon detecting the EA PLMN, the UE passively monitors the EA PLMN for a SIB12 broadcast message for a configurable amount of time. Upon receiving the SIB12 broadcast message comprising an emergency alert, the UE provides the emergency alert (such as via an audible sound via speakers of the UE or on a display via a user interface of the UE).