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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.
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 Wireless Emergency Alerts standards, WEA - formerly known as CMAS in North America, EU-Alert in Europe, LAT-Alert in South America, Earthquake 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.
General Packet Radio Service (GPRS), also called 2.5G, is a mobile data standard on the 2G cellular communication network's global system for mobile communications (GSM). Networks and mobile devices with GPRS started to roll out around the year 2001. At the time of introduction it offered for the first time seamless mobile data transmission using packet data for an "always-on" connection, providing improved Internet access for web, email, WAP services, and Multimedia Messaging Service (MMS).
Short Message Service, commonly abbreviated as SMS, is a text messaging service component of most telephone, Internet and mobile device systems. It uses standardized communication protocols that let mobile phones exchange short text messages, typically transmitted over cellular networks.
In telecommunication, a public land mobile network (PLMN) is a combination of wireless communication services offered by a specific operator in a specific country. A PLMN typically consists of several cellular technologies like GSM/2G, UMTS/3G, LTE/4G, NR/5G, offered by a single operator within a given country, often referred to as a cellular network.
The GPRS core network is the central part of the general packet radio service (GPRS) which allows 2G, 3G and WCDMA mobile networks to transmit Internet Protocol (IP) packets to external networks such as the Internet. The GPRS system is an integrated part of the GSM network switching subsystem.
Mobility management is one of the major functions of a GSM or a UMTS network that allows mobile phones to work. The aim of mobility management is to track where the subscribers are, allowing calls, SMS and other mobile phone services to be delivered to them.
Unstructured Supplementary Service Data (USSD), sometimes referred to as "quick codes" or "feature codes", is a communications protocol used by GSM cellular telephones to communicate with the mobile network operator's computers. USSD can be used for WAP browsing, prepaid callback service, mobile-money services, location-based content services, menu-based information services, and as part of configuring the phone on the network. The service does not require a messaging app, and does not incur charges.
An emergency population warning is a method where by local, regional, or national authorities can contact members of the public to warn them of an impending emergency. These warnings may be necessary for a number of reasons, including:
Multimedia Broadcast Multicast Services (MBMS) is a point-to-multipoint interface specification for existing 3GPP cellular networks, which is designed to provide efficient delivery of broadcast and multicast services, both within a cell as well as within the core network. For broadcast transmission across multiple cells, it defines transmission via single-frequency network configurations. The specification is referred to as Evolved Multimedia Broadcast Multicast Services (eMBMS) when transmissions are delivered through an LTE network. eMBMS is also known as LTE Broadcast.
The Short Message Service is realised by the use of the Mobile Application Part (MAP) of the SS7 protocol, with Short Message protocol elements being transported across the network as fields within the MAP messages. These MAP messages may be transported using "traditional" TDM based signalling, or over IP using SIGTRAN and an appropriate adaptation layer.
In telecommunications, 5G is the fifth-generation technology standard for cellular networks, which cellular phone companies began deploying worldwide in 2019, and is the successor to 4G technology that provides connectivity to most current mobile phones.
In mobile telephony GSM 03.38 or 3GPP 23.038 is a character encoding used in GSM networks for SMS, CB and USSD. The 3GPP TS 23.038 standard defines GSM 7-bit default alphabet which is mandatory for GSM handsets and network elements, but the character set is suitable only for English and a number of Western-European languages. Languages such as Chinese, Korean or Japanese must be transferred using the 16-bit UCS-2 character encoding. A limited number of languages, like Portuguese, Spanish, Turkish and a number of languages used in India written with a Brahmic scripts may use 7-bit encoding with national language shift table defined in 3GPP 23.038. For binary messages, 8-bit encoding is used.
Wireless Emergency Alerts, is an alerting network in the United States designed to disseminate emergency alerts to mobile devices such as cell phones and pagers. Organizations are able to disseminate and coordinate emergency alerts and warning messages through WEA and other public systems by means of the Integrated Public Alert and Warning System.
The Integrated Public Alert and Warning System (IPAWS) is an architecture that unifies the United States' Emergency Alert System, National Warning System, Wireless Emergency Alerts, and NOAA Weather Radio, under a single platform. IPAWS was designed to modernize these systems by enabling alerts to be aggregated over a network and distributed to the appropriate system for public dissemination.
Data Coding Scheme is a one-octet field in Short Messages (SM) and Cell Broadcast Messages (CB) which carries a basic information how the recipient handset should process the received message. The information includes:
Emergency Mobile Alerts (EMA) is an alerting network in New Zealand designed to disseminate emergency alerts to mobile devices. Emergency Mobile Alerts are messages about emergencies sent by New Zealand authorised emergency agencies to capable mobile phones. The alerts are sent to participating wireless providers who will distribute the alerts to their customers with compatible devices via Cell Broadcast, a technology best suitable for public warning as it simultaneously delivers messages to all phones using a Mobile Cell tower. Similar solutions are implemented in the United States, The Netherlands (NL-Alert), European Union (EU-Alert), Canada, Japan, Taiwan, Chile, Philippines. One2many B.V. provides this modern Emergency Mobile Alert system including the Cell Broadcast systems and the CAP based centralised Public Warning management system.
Reverse 1-1-2 is a public safety communications technology used by public safety organizations throughout the world to communicate with groups of people in a defined geographic area. Reverse 1-1--2 allows authorities to rapidly warn those in danger, directly through their mobile phones.
EU-Alert is the generic term for the European Public Warning Service based upon Cell Broadcast technology.
Emergency Cell Broadcast System (ECBS) is an alert broadcast system in the Philippines, designed to disseminate emergency alerts and warnings to mobile devices via cell broadcast services (CBS)
The United Kingdom's mobile phone alert system is an emergency population warning system that uses cell broadcast. The coalition government first considered the technology in 2013-2015 but the project was shelved due to concerns over the cost, following the coronavirus pandemic the first test alert sent in May 2021. The warning system is intended for use in major incidents such as flooding or terror attacks. The Emergency Alert System was launched on 19 March 2023, and tested on a nationwide basis for the first time on 23 April 2023.