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Method of sending messages to multiple mobile phone users From Wikipedia, the free encyclopedia
Cell Broadcast (CB) is a method of sending short messages to multiple mobile telephone users in a defined area at the same time. It is defined by the ETSI's GSM committee and 3GPP and is part of the 2G, 3G, 4G LTE (telecommunication) and 5G standards.[1] It is also known as Short Message Service-Cell Broadcast (SMS-CB or CB SMS).[2][3] Unlike Short Message Service-Point to Point (SMS-PP), Cell Broadcast is a one-to-many geo-targeted and geo-fenced messaging service.
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Cell Broadcast messaging was first demonstrated in Paris in 1997. Some mobile operators used Cell Broadcast for communicating the area code of the antenna cell to the mobile user (via channel 050),[4] for nationwide or citywide alerting, weather reports, mass messaging, location-based news, etc. Cell broadcast has been widely deployed since 2008 by major Asian, US, Canadian, South American and European network operators. Not all operators have the Cell Broadcast messaging function activated in their network yet, but most of the currently used handsets support cell broadcast, however on many devices it is disabled by default and there isn't a standardised interface to enable the feature.[1]
One Cell Broadcast message can reach a large number of telephones at once. Cell Broadcast messages are directed to specific radio cells of a mobile phone network, rather than to a specific telephone.[5] The latest generation of Cell Broadcast Systems (CBS) can send to the whole mobile network (e.g. 1,000,000 cells) in less than 10 seconds, reaching millions of mobile subscribers at the same time. A Cell Broadcast message is an unconfirmed push service, meaning that the originators of the messages do not know who has received the message, allowing for services based on anonymity.[1] Cell Broadcast is compliant with the latest EU General Data Protection Regulation (GDPR) as mobile phone numbers are not required by CB. The originator (alerting authority) of the Cell Broadcast message can request the success rate of a message. In such a case the Cell Broadcast System will respond with the number of addressed cells and the number of cells that have broadcast the Cell Broadcast (alert) message.
Each radio cell covers a certain geographic area, typically a few kilometers in diameter, so by only sending the Cell Broadcast message to specific radio cells, the broadcast can be limited to a specific area (geotargeting). This is useful for messages that are only relevant in a specific area, such as flood warnings.
The CB message parameters contain the broadcasting schedule. If the start-time is left open, the CBC system will assume an immediate start, which will be the case for Public Warning messages. If the end-time is left open, the message will be repeated indefinitely. A subsequent cancel message shall be used to stop this message. The repetition rate can be set between 2 seconds and to values beyond 30 minutes. Each repeated CB message will have the same message identifier (indicating the source of the message), and the same serial number. Using this information, the mobile telephone is able to identify and ignore broadcasts of already received messages.
A Cell Broadcast message page is composed of 82 octets, which, using the default character set, can encode 93 characters. Up to 15 of these pages may be concatenated to form a Cell Broadcast message[1] (hence maximum length of one Cell Broadcast message is therefore 1395 characters).[3]
A Cell Broadcast Centre (CBC), a system which is the source of SMS-CB message, is connected to a Base Station Controller (BSC) in GSM networks, to a Radio Network Controller (RNC) in UMTS networks, to a Mobility Management Entity (MME) in LTE (telecommunication) networks or to a core Access and Mobility management Function (AMF) in 5G networks.
The technical implementation of the Cell Broadcast service is described in the 3GPP specification TS 23.041 [6]
A CBC sends CB messages, a list of cells where messages are to be broadcast, and the requested repetition rate and number of times they shall be broadcast to the BSC/RNC/MME/AMF. The BSC's/RNC's/MME/AMF responsibility is to deliver the CB messages to the base stations (BTSs), Node Bs, ENodeBs and gNodeBs which handle the requested cells.
Cell Broadcast is not affected by traffic load; therefore, it is very suitable during a disaster when load spikes of data (social media and mobile app), regular SMS and voice calls usage (mass call events) tend to significantly congest mobile networks, as multiple events have shown.
Broadcast messages are used in most countries to send emergency alerts, using as input a CAP (Common Alerting Protocol) message as specified by OASIS (organization) or Wireless Emergency Alerts (WEA) C-interface protocol, which has been specified jointly by the Alliance for Telecommunications Industry Solutions (ATIS) and the Telecommunications Industry Association (TIA).
Advantages of using Cell Broadcast for Public warning are:
A point of criticism in the past on Cell Broadcast was that there was no uniform user experience on all mobile devices in a country.[1]
Wireless Emergency Alerts and Government alerts using Cell Broadcast are supported in most models of mobile telephones. Some smart phones have a configuration menu that offer opt-out capabilities for certain public warning severity levels.[4][7]
In case a national civil defence organisation is adopting one of the 3GPP's Public Warning System standards, PWS - also known as CMAS in North America, EU-Alert in Europe, LAT-Alert in South America, Earthquake and Tsunami Warning System in Japan, each subscriber in that country either making use of the home network or its roaming automatically makes use of the embedded Public warning Cell Broadcast feature present in every Android (operating system)[4] and iOS mobile device.[7]
In countries[who?] that have selected Cell Broadcast to transmit public warning messages, up to 99% of the handsets receive the cell broadcast message (reaching between 85-95% of the entire population as not all people have a mobile phone) within seconds after the government authorities have submitted the message; see as examples Emergency Mobile Alert (New Zealand), Wireless Emergency Alerts (USA) and NL-Alert (Netherlands).
Many countries and regions have implemented location-based alert systems based on cell broadcast. The alert messages to the population, already broadcast by various media, are relayed over the mobile network using cell broadcast.
The following countries and regions have selected Cell Broadcast to use for their national public warning system but are currently in the process of implementing.
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