Emergency Warning¶

Cellular Networks cannot only be used for individual 1:1 communication between peers, but also provide limited broadcast capabilities that can be used to deliver emergency warnings, e.g. in case of natural disasters such as earthquakes.

Contrary to various frequently-propagated solutions on the application layer (such as apps for smartphones), the broadcast mechanisms built into cellular networks are able to reach every mobile subscriber simultaneously within very few seconds. It's true broadcast, not point-to-point communication with individual phones.

Many countries and regions have specified emergency warning systems based on the underlying technology in cellular networks, including:

• ETWS, the Earthquake and Tsunami Warning System
• KPAS, the Korean Public Alerting System
• WEA, the US-American Wireless Emergency Alert system
• EU-Alert, the EU public alerting system (with national implementations such as NL-Alert, UK-Alert)

These are the technological building blocks to Cellular Emergency warnings:

1. Cell_Broadcast (in 2G) and Service_Area_Broadcast (in 3G), which provide the ability to send broadcast messages from the network to many/all subscribers in a given coverage area
2. ETWS Primary Notifications, which provide an ultra-fast mechanism to inform all subscribers of an emergency (without the ability to include text), whether or not they are currently idle/camping, in an active dedicated channel or in packet transfer mode
3. PWS (Public Warning System), the successor of the above technologies in 4G/LTE.

Starting in 2019, due to a grant from the German ministry of Education and Research, Osmocom has gained support for Cell_Broadcast and ETWS.

In order to use the results in an all-Osmocom network, you need the following:

1. complete Osmocom network with recent software from September 2019 or later
2. ensure your BTSs are configured (in the BSC) to have a CBCH (Cell Broadcast Channel) as part of their CCCH configuration. Consult the OsmoBTS user manual in case of doubt.
3. configure your BSC to connect to the CBC using the VTY commands for CBSP remote-ip/remote-port. Consult the OsmoBSC user manual in case of doubt.
4. add one instance of osmo-cbc to your network

OsmoCBC now provide a REST/JSON interface based on which external programs (so-called CBEs) can request the transmission of cell broadcast and emergency messages.