Cell broadcast

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Standard cell broadcast configuration menu on Android 8.0

Cell Broadcast , also known as SMS-CB , is a cellular service that has been used by Asian, American and European network operators since 1999 to send messages similar to SMS-MO to all recipients within a radio cell . Unlike SMS-MO messages, which are only addressed to one recipient, a cell broadcast message is sent from the base station to all cell phones that are located in this radio cell and have activated the service. It is standardized by the 3rd Generation Partnership Project (3GPP) and part of 2G , 3G , 4G and 5GStandards. The service is relatively robust due to its anchoring in the standards, few external dependencies and the technically simple structure.

The messages consist of alphanumeric characters, including non-Latin alphabets. This means that web links can be specified, but graphics cannot be sent. Multilingualism is possible, but limited by the message length of 1395 characters. A cell broadcast message is an unconfirmed push service , so no cell phone numbers are required and there is a certain degree of anonymity. Accordingly, the sender of the messages does not know who received them. The latest generation of cell broadcast systems should be able to send a message to hundreds of thousands of cells in a few seconds and thus to reach millions of mobile radio subscribers.

Technical implementation

Cell broadcast is developed by the GSM committee of ETSI and 3GPP and is part of the 2G, 3G, 4G and 5G cellular standards (specification 3GPP TS 23.041).

A Cell Broadcast Center (CBC) is connected to one of the following:

  • BSC in GSM networks (described in the 3GPP standard TS 48.049)
  • RNC in UMTS networks (described in the 3GPP standard TS 25.419)
  • MME in LTE networks (described in the 3GPP standard TS 29.168)
  • AMF in 5G networks. (described in 3GPP standard TS 29.518)

Due to the coding used, the transmissions correspond to a maximum of 82 bytes or 93 characters; by concatenating 15 messages one reaches 1395 characters. Characters can be represented with the UCS-2 coding (similar to UTF-16). Cell broadcast is not affected by the network traffic load because the communication is unidirectional . This is particularly beneficial during disasters, when peak loads cause the cellular network to slow down significantly and data (social media, warning apps), SMS-MO and voice calls (mass call events) do not work as usual.

Examples

Examples of warning systems that use cell broadcast as the primary mobile alarm channel:

EU-Alert / NL-Alert Cell Broadcast in the Venlo area ( Netherlands ) on August 7, 2018 due to a major fire

Usage history

In Germany, the function is not activated for all operators, but practically all cell phones and smartphones support cell broadcast. At times there were channels with different topics such as news ( ProSieben , Handelsblatt ), online offers (snap123 on channel 123 in the D2 network) and weather forecasts. Since these are withdrawing more and more, many providers only have basic topics available (location determination, tariff information ). Since CB is free for the user, these services were mostly financed by sponsors.

In general, channel 50 is used in many countries by a wide variety of mobile radio providers for location information. For example, the local area code, which is relevant for certain tariffs, was transmitted on Vodafone on CB channels 50 and 100; on April 1, 2009 this information was discontinued. Vodafone in Germany offered the so-called Vodafone ticker; this required cell phones equipped with a special client; this has been referred to as "extended cell broadcast". The vodafone ticker service was discontinued on December 31, 2006 and resumed on January 1, 2008. On channel 837, Vodafone transmits the date and time at irregular intervals, accurate to ten minutes, and on channel 833 the network element designation (as of June 2008). O₂ sends the position of the base station in Gauß-Krüger coordinates on channel 221 . This means that the mobile phones know the location of the base station and can display home and a house if the phone is in the home zone - i.e. H. in the base station defined as the home zone - or city , if it is in the city zone . The first six digits, supplemented by zero, result in the easting value, the last six digits with an appended zero the northing value. Telekom Deutschland has stopped sending cell broadcast messages after a test run. E-Plus never introduced this service.

In Switzerland, Swisscom sends the name of the region or city in which you are on channel 50. Larger cities are usually divided into several geographical areas (e.g. Zurich Airport, Zurich North-West, Zurich West, etc.).

After the floods in Western and Central Europe in 2021 , there were calls to use the service in Germany to warn the population in the event of disasters.

Web links

Individual evidence

  1. ↑ Dafu - data radio in Germany (Cell Broadcast). Retrieved September 10, 2020 .
  2. ↑ 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC): Technical realization of Cell Broadcast Service (CBS). September 2020, accessed on October 17, 2020 .
  3. ↑ a b Beleving NL-Alert bij burgers. July 2, 2020, accessed October 20, 2020 (Dutch).
  4. ↑ Marion Choppin: GeoSafe. Intersec, accessed October 17, 2020 (UK English).
  5. ^ Mobile Network Public Warning Systems and the Rise of Cell Broadcast. GSMA , January 2013, accessed October 16, 2020 .
  6. ^ Fire and explosion in Venlo . In: RP online . Retrieved August 7, 2018.
  7. ^ Lithuania Public Warning and Information System .
  8. ↑ UK EU alert system active in 2021 .
  9. ↑ Italy EU Alert System active 2020 .
  10. ^ Taiwan Public Warning Cell Broadcast Service .
  11. ↑ Peruvian public warning system SISMATE .
  12. ↑ Cell broadcast. In: Android wiki. Android / Google, accessed October 17, 2020 .
  13. ↑ About emergency and government alerts on iPhone and Apple Watch. Apple Inc., August 14, 2019, accessed October 17, 2020 .
  14. ↑ Vodafone switches off Cellbroadcast service , teltarif.de, March 27, 2009.
  15. ↑ Incomplete list of cell broadcast location reports from Swisscom on channel 50. Accessed on July 22, 2021 .
  16. ^ Sascha Lobo : The bureaucratic mockery of the 21st century. In: spiegel.de , July 21, 2021.
  17. ↑ Matthias Koch: The Cell Broadcast Scandal: The Flood Dead Could Still Live . In: rnd.de , July 21, 2021.
  18. ↑ Achim Sawall: Telekom wants to set up cell broadcast warning system . In: golem.de , July 21, 2021.