Designing an efficient communications protocol to deliver alert messages to the population during crisis through GNSS

Multi-channel Early Warning Systems are currently used to warn the population at risk and reduce the impact of crisis. Nevertheless, satellite networks, which offer robust and reliable communication solutions during major disaster events, are not yet being fully considered for direct communication to the citizens. The paper will address solutions for the transmission of alert messages to warn/inform the population in risk during crisis through GNSS. The solution proposed is based on a protocol for alert messages that is compatible with the Common Alert Protocol (CAP), but lightweight in comparison with CAP, so that it can be applied over a variety of communication links, i.e. over different communication standards, even in very narrow band channels, such as Satellite-Based Augmentation System (SBAS). The paper will analyse the opportunities and implications of using GNSS to disseminate alert messages to the population and propose the principles for a flexible protocol that allows the translation of CAP messages (XML-based) into a very flexible and lightweight protocol for transmission in very narrow band channels.