GNSS-based emergency message service: Lessons learned and future prospects

Integrating navigation and communication for emergency message services through Global Navigation Satellite System (GNSS) signals is under consideration in Europe and Japan. A GNSS satellite continuously transmits ranging signals and messages. These messages include information about the satellite's orbit, ionospheric conditions, satellite health, etc. In a next generation of these systems or utilizing spare bits available in the current systems, data bandwidth could be utilized to transmit additional information, for example during large scale emergency situations. Recently the use of GNSS in mobile telephones has increased. The GNSS receivers applied in these devices could be utilized to distribute information in a specific area, and thus utilized for alarming and informing the population at the time of an emergency. The GNSS based emergency message services could combine the advantages of both satellite communication and mobile telephone based services as it has high resilience (less dependent of ground infrastructure), its trustworthiness as it is institutionally owned, and its sensitivity to the location of the user and its potentially lower operational cost compared to other systems. Utilizing real signals from the first QZSS satellite, we confirmed the reception status of the emergency message in the urban area in order to deliver the disaster information during a large scale disaster. In addition, we examined the effect of the transmission interval of the emergency message on the distribution of the disaster information as we deliver the emergency message in-between the navigation messages.