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Introduction of DE-ALERT: Case study of Cell Broadcast Service accompanied by lab demo

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Prof. Wietfeld explaining the live demonstration during the lecture © CNI

CNI aims to illustrates the practical impact of the content of its lectures by continuously integrating case studies of emerging topics in its lectures. Within this week's lecture on Mobile Radio Networks, Prof. Wietfeld gave a brief live demonstration of the cell broadcast service, which is currently being introduced in Germany to provide faster and broader warning to the public in case of disasters such as floodings or fires. The technical capabilities of cell broadcasting have already been available with 2G networks and many countries have implemented the services ever since. The EU mandates the introduction in all EU countries as part of the EU-ALERT directive.


Currently, there is no universal warning system available for the German population. One solution to this problem will be cell broadcasts (the so-called DE-ALERT service), which can be used to warn all subscribers currently connected to a cellular cell without having to install a specific app such as NINA and KATWARN. Therefore, one of the advantages is that a larger share of the population may be reached. Moreover, the warnings are not simply push notifications but on-screen notifications which may optionally be accompanied by vibrations of the smartphone and an audio message. A first test of the functionality shall take place in 2022 during the German nationwide altert day: "Warntag 2022".  The exact date has not yet been announced. While the call broadcasting technology is generally mature, recent press coverage indicates that the introduction in Germany faces some interoperability problems due to different smartphone operating systems and software versions.  

To practically illustrate how such a service would work on real-life smartphones, Prof. Wietfeld discussed the technical background with his students and provided a brief live demonstration of such cell broadcasts within last week's Mobile Radio Networks 2 (MRN2) lecture. Using a commercial cellular network emulator, a current Android smartphone was placed in a so-called shielding box which is connected via HF cables to a LTE cell. After configuring and triggering the warning messages within the network emulator, the smartphone reliably displayed CMAS messages and ETWS notifications on top of other active apps on the smartphone once they were sent out by the network. At the same time, it generated sounds and vibrations or displayed the specific warning message of the network operator.

As part of its technology monitoring within the Competence Centre 5G.NRW, the CNI team further investigated whether current 5G-enabled smartphones are also able to receive Cell Broadcast Messages via 5G networks. Thus, CNI recreated such a system with an updated network emulator smartphone experimental setup. Similar to the 4G demonstration during the lecture, the same behavior was observed for 5G Non-Standalone (NSA).

Although the demonstrations focussed on selected smartphones types only and was not meant as an in-depth study of potential interoperability issues, it was shown that 4G as well as 5G cell broadcasts are generally feasible and suitable to extend public safety provisions beyond the voluntary use of warning apps.

Location & approach

The campus of TU Dort­mund University is located close to interstate junction Dort­mund West, where the Sauerlandlinie A 45 (Frankfurt-Dort­mund) crosses the Ruhrschnellweg B 1 / A 40. The best interstate exit to take from A 45 is “Dort­mund-Eichlinghofen” (closer to South Campus), and from B 1 / A 40 “Dort­mund-Dorstfeld” (closer to North Campus). Signs for the uni­ver­si­ty are located at both exits. Also, there is a new exit before you pass over the B 1-bridge leading into Dort­mund.

To get from North Campus to South Campus by car, there is the connection via Vogelpothsweg/Baroper Straße. We recommend you leave your car on one of the parking lots at North Campus and use the H-Bahn (suspended monorail system), which conveniently connects the two campuses.

TU Dort­mund University has its own train station (“Dort­mund Uni­ver­si­tät”). From there, suburban trains (S-Bahn) leave for Dort­mund main station (“Dort­mund Hauptbahnhof”) and Düsseldorf main station via the “Düsseldorf Airport Train Station” (take S-Bahn number 1, which leaves every 20 or 30 minutes). The uni­ver­si­ty is easily reached from Bochum, Essen, Mülheim an der Ruhr and Duisburg.

You can also take the bus or subway train from Dort­mund city to the uni­ver­si­ty: From Dort­mund main station, you can take any train bound for the Station “Stadtgarten”, usually lines U41, U45, U 47 and U49. At “Stadtgarten” you switch trains and get on line U42 towards “Hombruch”. Look out for the Station “An der Palmweide”. From the bus stop just across the road, busses bound for TU Dort­mund University leave every ten minutes (445, 447 and 462). Another option is to take the subway routes U41, U45, U47 and U49 from Dort­mund main station to the stop “Dort­mund Kampstraße”. From there, take U43 or U44 to the stop “Dort­mund Wittener Straße”. Switch to bus line 447 and get off at “Dort­mund Uni­ver­si­tät S”.

The AirportExpress is a fast and convenient means of transport from Dortmund Airport (DTM) to Dortmund Central Station, taking you there in little more than 20 minutes. From Dortmund Central Station, you can continue to the university campus by interurban railway (S-Bahn). A larger range of international flight connections is offered at Düsseldorf Airport (DUS), which is about 60 kilometres away and can be directly reached by S-Bahn from the university station.

The H-Bahn is one of the hallmarks of TU Dort­mund University. There are two stations on North Campus. One (“Dort­mund Uni­ver­si­tät S”) is directly located at the suburban train stop, which connects the uni­ver­si­ty directly with the city of Dort­mund and the rest of the Ruhr Area. Also from this station, there are connections to the “Technologiepark” and (via South Campus) Eichlinghofen. The other station is located at the dining hall at North Campus and offers a direct connection to South Campus every five minutes.

The facilities of TU Dortmund University are spread over two campuses, the larger Campus North and the smaller Campus South. Additionally, some areas of the university are located in the adjacent “Technologiepark”.

Site Map of TU Dortmund University (Second Page in English).