Bluetooth
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Bluetooth is a short-range
wireless Wireless communication (or just wireless, when the context allows) is the telecommunication, transfer of information between two or more points that do not use an electrical conductor as a medium by which to perform the transfer. The most common ...

wireless
technology standard used for exchanging data between fixed and mobile devices over short distances using
UHF Ultra high frequency (UHF) is the ITU designation for radio frequencies in the range between 300 megahertz The hertz (symbol: Hz) is the SI derived unit, derived unit of frequency in the International System of Units (SI) and is defin ...

UHF
radio wave Radio waves are a type of electromagnetic radiation In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is the natural science that studies ma ...
s in the ISM bands, from 2.402 GHz to 2.48GHz, and building
personal area network A personal area network (PAN) is a computer network A computer network is a group of computers that use a set of common communication protocols over digital signal, digital interconnections for the purpose of sharing resources located on or p ...
s (PANs). It was originally conceived as a wireless alternative to
RS-232 In telecommunications, RS-232, Recommended Standard (EIA), Recommended Standard 232 is a technical standard, standard originally introduced in 1960 for serial communication transmission of data. It formally defines signals connecting between a ...
data cables. Bluetooth is managed by the
Bluetooth Special Interest Group The Bluetooth Special Interest Group (Bluetooth SIG) is the standards organization A standards organization, standards body, standards developing organization (SDO), or standards setting organization (SSO) is an organization whose primary funct ...
(SIG), which has more than 35,000 member companies in the areas of telecommunication, computing, networking, and consumer electronics. The
IEEE The Institute of Electrical and Electronics Engineers (IEEE) is a professional association A professional association (also called a professional body, professional organization, or professional society) seeks to advocacy, further a particul ...
standardized Bluetooth as IEEE 802.15.1, but no longer maintains the standard. The Bluetooth SIG oversees development of the specification, manages the qualification program, and protects the trademarks. A manufacturer must meet Bluetooth SIG standards to market it as a Bluetooth device. A network of
patent A patent is a type of intellectual property that gives its owner the legal right to exclude others from making, using, or selling an invention for a limited period of years in exchange for publishing an sufficiency of disclosure, enabling disclo ...

patent
s apply to the technology, which are licensed to individual qualifying devices. , Bluetooth
integrated circuit An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuits on one small flat piece (or "chip") of semiconductor material, usually silicon. Transistor count, Larg ...

integrated circuit
chips ship approximately million units annually.


Etymology

The name “Bluetooth” was proposed in 1997 by Jim Kardach of
Intel Intel Corporation is an American multinational corporation and technology company headquartered in Santa Clara, California, Santa Clara, California. It is the world's largest semiconductor chip manufacturer by revenue, and is the developer of ...

Intel
, who developed a system that would allow mobile phones to communicate with computers. At the time of this proposal, he was reading
Frans G. Bengtsson Frans Gunnar Bengtsson (4 October 1894 – 19 December 1954) was a Swedish novelist, essayist, poet and biographer. He was born in Tåssjö (now in Ängelholm Municipality) in Skåne Scania ( sv, Skåne ()), is the southernmost of the his ...

Frans G. Bengtsson
's historical novel ''
The Long Ships ''The Long Ships'' or ''Red Orm'' (original Swedish: ''Röde Orm'' meaning ''Red Serpent'' or ''Red Snake'') is an adventure novel by the Swedish writer Frans G. Bengtsson. The narrative is set in the late 10th century and follows the adventur ...
'' about Vikings and the 10th-century Danish King
Harald Bluetooth Harald "Bluetooth" Gormsson ( non, Haraldr Gormsson; da, Harald Blåtand Gormsen, died c. 985/86) was a king of Denmark Denmark ( da, Danmark, ), officially the Kingdom of Denmark, da, Kongeriget Danmark, . See also: The unity of the Real ...
. Bluetooth is the
Anglicised Linguistic anglicisation (or anglicization, occasionally anglification, anglifying, or Englishing) is the practice of modifying foreign words, names, and phrases to make them easier to spell, pronounce, or understand in English language, English. ...
version of the Scandinavian ''Blåtand''/''Blåtann'' (or in
Old Norse Old Norse, Old Nordic, or Old Scandinavian is a stage of development of North Germanic languages, North Germanic dialects before their final divergence into separate Nordic languages. Old Norse was spoken by inhabitants of Scandinavia and th ...
''blátǫnn''). It was the
epithet An epithet (, ) is a byname, or a descriptive term (word or phrase), accompanying or occurring in place of a name and having entered common usage. It has various shades of meaning when applied to seemingly real or fictitious people, divinities, o ...
of King Harald Bluetooth who united dissonant Danish tribes into a single kingdom, the implication being that Bluetooth unites communication protocols.


Logo

The Bluetooth logo is a
bind rune A bind rune ( is, bandrún) is a ligature of two or more runes. They are extremely rare in Viking Age inscriptions, but are common in earlier ( Proto-Norse) and later (medieval) inscriptions.Enoksen, Lars Magnar (1998). ''Runor: historia, tydni ...
merging the
Younger Futhark The Younger Futhark, also called Scandinavian runes, is a runic alphabet and a reduced form of the Elder Futhark, with only 16 characters, in use from about the 9th century, after a "transitional period" during the 7th and 8th centuries. The r ...
runes Runes are the letters in a set of related alphabet An alphabet is a standardized set of basic written symbols or graphemes (called letter (alphabet), letters) that represent the phonemes of certain spoken languages. Not all writing syste ...
 (ᚼ,
Hagall
Hagall
) and  (ᛒ,
Bjarkan
Bjarkan
), Harald's initials.


History

The development of the "short-link" radio technology, later named Bluetooth, was initiated in 1989 by Nils Rydbeck, CTO at
Ericsson Mobile (lit. ''Telephone Stock Company of LM Ericsson''), commonly known as Ericsson, is a Swedish multinational networking and telecommunications company headquartered in Stockholm Stockholm is the Capital city, capital of Sweden. It has t ...
in
Lund Lund (, , ) is a city in the southern Swedish provinces of Sweden, province of Scania, across the Øresund, Öresund strait from Copenhagen. The town had 91,940 inhabitants out of a municipal total of 121,510 . It is the seat of Lund Municipalit ...

Lund
, Sweden. The purpose was to develop wireless headsets, according to two inventions by Johan Ullman, and . Nils Rydbeck tasked Tord Wingren with specifying and Dutchman
Jaap HaartsenJacobus Cornelis Haartsen (born 13 February 1963, The Hague, Netherlands) is a Dutch people, Dutch electrical engineer, researcher, inventor and entrepreneur best known for his role in producing the specification for Bluetooth. He obtained his maste ...
and Sven Mattisson with developing. Both were working for Ericsson in Lund. In 1990, Jaap Haartsen was nominated by the European Patent Office for the European Inventor Award. From 1997 Örjan Johansson became the project leader and propelled the technology and standardization. In 1997, Adalio Sanchez, then head of IBM ThinkPad product R&D, approached Nils Rydbeck about collaborating on integrating a
mobile phone A mobile phone, cellular phone, cell phone, cellphone, handphone, or hand phone, sometimes shortened to simply mobile, cell or just phone, is a portable telephone that can make and receive telephone call, calls over a radio frequency link wh ...

mobile phone
into a ThinkPad notebook. The two assigned engineers from Ericsson and IBM to study the idea. The conclusion was that power consumption on cellphone technology at that time was too high to allow viable integration into a notebook and still achieve adequate battery life. Instead, the two companies agreed to integrate Ericsson's short-link technology on both a ThinkPad notebook and an Ericsson phone to accomplish the goal. Since neither IBM ThinkPad notebooks nor Ericsson phones were the market share leaders in their respective markets at that time, Adalio Sanchez and Nils Rydbeck agreed to make the short-link technology an open industry standard to permit each player maximum market access. Ericsson contributed the short-link radio technology, and IBM contributed patents around the logical layer. Adalio Sanchez of IBM then recruited Stephen Nachtsheim of Intel to join and then Intel also recruited Toshiba and Nokia. In May 1998, the Bluetooth SIG was launched with IBM and Ericsson as the founding signatories and a total of five members: Ericsson, Intel, Nokia, Toshiba and IBM. The first consumer Bluetooth device was launched in 1999. It was a hands-free mobile headset that earned the "Best of show Technology Award" at COMDEX. The first Bluetooth mobile phone was the Ericsson T36 but it was the revised T39 model that actually made it to store shelves in 2001. In parallel, IBM introduced the IBM ThinkPad A30 in October 2001 which was the first notebook with integrated Bluetooth. Bluetooth's early incorporation into consumer electronics products continued at Vosi Technologies in Costa Mesa, California, USA, initially overseen by founding members Bejan Amini and Tom Davidson. Vosi Technologies had been created by real estate developer Ivano Stegmenga, with United States Patent 608507, for communication between a cellular phone and a vehicle's audio system. At the time, Sony/Ericsson had only a minor market share in the cellular phone market, which was dominated in the USA by Nokia and Motorola. Due to ongoing negotiations for an intended licensing agreement with Motorola beginning in the late 1990s, Vosi could not publicly disclose the intention, integration and initial development of other enabled devices which were to be the first “
Smart Home ''SMart'' was a British CBBC CBBC (short for Children's BBC, also known as the CBBC Channel) is a British free-to-air children's television Children's television series are television programs designed for children, normally scheduled for br ...
” internet connected devices. Vosi needed a means for the system to communicate without a wired connection from the vehicle to the other devices in the network. Bluetooth was chosen, since WiFi was not yet readily available or supported in the public market. Vosi had begun to develop the Vosi Cello integrated vehicular system and some other internet connected devices, one of which was intended to be a table-top device named the Vosi Symphony, networked with Bluetooth. Through the negotiations with Motorola, Vosi introduced and disclosed its intent to integrate Bluetooth in its devices. In the early 2000s
legal battle
ensued between Vosi and Motorola, which indefinitely suspended release of the devices. Later, Motorola implemented it in their devices which initiated the significant propagation of Bluetooth in the public market due to its large market share at the time.


Implementation

Bluetooth operates at frequencies between 2.402 and 2.480GHz, or 2.400 and 2.4835GHz including
guard band In radio, a guard band is an unused part of the radio spectrum The radio spectrum is the part of the electromagnetic spectrum The electromagnetic spectrum is the range of frequencies (the spectrum A spectrum (plural ''spectra'' or ''spec ...
s 2MHz wide at the bottom end and 3.5MHz wide at the top. This is in the globally unlicensed (but not unregulated) industrial, scientific and medical ( ISM) 2.4GHz short-range radio frequency band. Bluetooth uses a radio technology called
frequency-hopping spread spectrum Frequency-hopping spread spectrum (FHSS) is a method of transmitting radio signals by rapidly changing the carrier frequency among many distinct frequencies occupying a large spectral band. The changes are controlled by a code known to both tra ...
. Bluetooth divides transmitted data into packets, and transmits each packet on one of 79 designated Bluetooth channels. Each channel has a bandwidth of 1MHz. It usually performs 1600hops per second, with adaptive frequency-hopping (AFH) enabled. Bluetooth Low Energy uses 2MHz spacing, which accommodates 40 channels. Originally,
Gaussian frequency-shift keying Frequency-shift keying (FSK) is a frequency modulation Frequency modulation (FM) is the encoding of information Information can be thought of as the resolution of uncertainty; it answers the question of "What an entity is" and thus de ...
(GFSK) modulation was the only modulation scheme available. Since the introduction of Bluetooth 2.0+EDR, π/4- (differential quadrature phase-shift keying) and 8-DPSK modulation may also be used between compatible devices. Devices functioning with GFSK are said to be operating in basic rate (BR) mode, where an instantaneous
bit rate In telecommunications and computing, bit rate (bitrate or as a variable ''R'') is the number of bits that are conveyed or processed per unit of time. The bit rate is expressed in the unit Data rate units, bit per second unit (symbol: ''bit/s'' ...
of 1
Mbit/s In telecommunications Telecommunication is the transmission of information by various types of technologies over wire, radio, Optical system, optical, or other Electromagnetism, electromagnetic systems. It has its origin in the desire of huma ...
is possible. The term Enhanced Data Rate (EDR) is used to describe π/4-DPSK and 8-DPSK schemes, each giving 2 and 3Mbit/s respectively. The combination of these (BR and EDR) modes in Bluetooth radio technology is classified as a ''BR/EDR radio''. In 2019, Apple published an extensio

called HDR which supports data rates up to 8Mbit/s. Bluetooth is a packet switching, packet-based protocol with a master/slave architecture. One master may communicate with up to seven slaves in a
piconet A piconet is an ad hoc network that links a wireless user group of devices using Bluetooth Bluetooth is a short-range wireless technology standard used for exchanging data between fixed and mobile devices over short distances using Ultra high ...

piconet
. All devices within a given piconet use the clock provided by the master as the base for packet exchange. The master clock ticks with a period of 312.5 μs, two clock ticks then make up a slot of 625µs, and two slots make up a slot pair of 1250µs. In the simple case of single-slot packets, the master transmits in even slots and receives in odd slots. The slave, conversely, receives in even slots and transmits in odd slots. Packets may be 1, 3, or 5 slots long, but in all cases, the master's transmission begins in even slots and the slave's in odd slots. The above excludes Bluetooth Low Energy, introduced in the 4.0 specification, which uses the same spectrum but somewhat differently.


Communication and connection

A master BR/EDR Bluetooth device can communicate with a maximum of seven devices in a piconet (an ad hoc computer network using Bluetooth technology), though not all devices reach this maximum. The devices can switch roles, by agreement, and the slave can become the master (for example, a headset initiating a connection to a phone necessarily begins as master—as an initiator of the connection—but may subsequently operate as the slave). The Bluetooth Core Specification provides for the connection of two or more piconets to form a
scatternet Image:BluetoothScatternet-de.svg, Scatternet (master (device), master=red, slave (device), slave=green, parking=blue) A scatternet is a type of ad hoc computer network consisting of two or more piconets. The terms "scatternet" and "piconet" are typ ...

scatternet
, in which certain devices simultaneously play the master role in one piconet and the slave role in another. At any given time, data can be transferred between the master and one other device (except for the little-used broadcast mode). The master chooses which slave device to address; typically, it switches rapidly from one device to another in a round-robin fashion. Since it is the master that chooses which slave to address, whereas a slave is (in theory) supposed to listen in each receive slot, being a master is a lighter burden than being a slave. Being a master of seven slaves is possible; being a slave of more than one master is possible. The specification is vague as to required behavior in scatternets.


Uses

Bluetooth is a standard wire-replacement communications protocol primarily designed for low power consumption, with a short range based on low-cost
transceiver In Radio, radio communication, a transceiver is a device that is able to both transmit and receive information through a transmission medium. It is a combination of a transmitter, ''trans''mitter and a Radio receiver, re''ceiver'', hence the name ' ...

transceiver
microchips An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuit File:PExdcr01CJC.jpg, 200px, A circuit built on a printed circuit board (PCB). An electronic circuit i ...

microchips
in each device. Because the devices use a radio (broadcast) communications system, they do not have to be in visual line of sight of each other; however, a '' quasi optical'' wireless path must be viable.Newton, Harold. (2007). ''Newton’s telecom dictionary.'' New York: Flatiron Publishing. Range is power-class-dependent, but effective ranges vary in practice. See the table "Ranges of Bluetooth devices by class". Officially Class 3 radios have a range of up to , Class 2, most commonly found in mobile devices, , and Class 1, primarily for industrial use cases,. Bluetooth Marketing qualifies that Class 1 range is in most cases , and Class 2 range . The actual range achieved by a given link will depend on the qualities of the devices at both ends of the link, as well as the air conditions in between, and other factors. The effective range varies depending on propagation conditions, material coverage, production sample variations, antenna configurations and battery conditions. Most Bluetooth applications are for indoor conditions, where attenuation of walls and signal fading due to signal reflections make the range far lower than specified line-of-sight ranges of the Bluetooth products. Most Bluetooth applications are battery-powered Class 2 devices, with little difference in range whether the other end of the link is a Class 1 or Class 2 device as the lower-powered device tends to set the range limit. In some cases the effective range of the data link can be extended when a Class 2 device is connecting to a Class 1 transceiver with both higher sensitivity and transmission power than a typical Class 2 device. Mostly, however, the Class 1 devices have a similar sensitivity to Class 2 devices. Connecting two Class 1 devices with both high sensitivity and high power can allow ranges far in excess of the typical 100m, depending on the throughput required by the application. Some such devices allow open field ranges of up to 1 km and beyond between two similar devices without exceeding legal emission limits. The Bluetooth Core Specification mandates a range of not less than , but there is no upper limit on actual range. Manufacturers' implementations can be tuned to provide the range needed for each case.


Bluetooth profile

To use Bluetooth wireless technology, a device must be able to interpret certain Bluetooth profiles, which are definitions of possible applications and specify general behaviors that Bluetooth-enabled devices use to communicate with other Bluetooth devices. These profiles include settings to parameterize and to control the communication from the start. Adherence to profiles saves the time for transmitting the parameters anew before the bi-directional link becomes effective. There are a wide range of Bluetooth profiles that describe many different types of applications or use cases for devices.


List of applications

* Wireless control and communication between a mobile phone and a
handsfree Hands-free phone kit fitted to a Saab 9-5. Handsfree is an adjective describing equipment that can be used without the use of hands (for example via voice command Speech recognition is an interdisciplinary Interdisciplinarity or interdisc ...

handsfree
headset. This was one of the earliest applications to become popular. * Wireless control of and communication between a mobile phone and a Bluetooth compatible car stereo system (and sometimes between the SIM card and the car phone). *Wireless communication between a smartphone and a smart lock for unlocking doors. * Wireless control of and communication with iOS and Android device phones, tablets and portable
wireless speaker Wireless speakers are loudspeakers that receive audio signals using radio frequency (RF) waves rather than over audio cables. The two most popular RF frequencies that support audio transmission to wireless loudspeakers include a variation of WiFi ...
s. * Wireless and
Intercom An intercom ("intercommunication device") or interphone is a stand-alone voice communications system for use within a building or small collection of buildings, functioning independently of the public telephone network. Intercoms are generally m ...

Intercom
. Idiomatically, a headset is sometimes called "a Bluetooth". * Wireless streaming of audio to
headphones Headphones are a pair of small Electrodynamic speaker driver, loudspeaker drivers worn on or around the head over a user's ears. They are electroacoustics (acoustical engineering), electroacoustic transducers, which convert an electrical sign ...

headphones
with or without communication capabilities. * Wireless streaming of data collected by Bluetooth-enabled fitness devices to phone or PC. * Wireless networking between PCs in a confined space and where little bandwidth is required. * Wireless communication with PC input and output devices, the most common being the
mouse A mouse, plural mice, is a small mammal Mammals (from Latin language, Latin , 'breast') are a group of vertebrate animals constituting the class (biology), class Mammalia (), and characterized by the presence of mammary glands which i ...

mouse
, keyboard and printer. * Transfer of files, contact details, calendar appointments, and reminders between devices with
OBEX OBEX (abbreviation of OBject EXchange, also termed IrOBEX) is a communications protocol that facilitates the exchange of binary objects between devices. It is maintained by the Infrared Data Association but has also been adopted by the Bluetooth ...

OBEX
and sharing directories via FTP. * Replacement of previous wired
RS-232 In telecommunications, RS-232, Recommended Standard (EIA), Recommended Standard 232 is a technical standard, standard originally introduced in 1960 for serial communication transmission of data. It formally defines signals connecting between a ...
serial communications in test equipment, GPS receivers, medical equipment, bar code scanners, and traffic control devices. * For controls where
infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is the natur ...

infrared
was often used. * For low bandwidth applications where higher
USB Universal Serial Bus (USB) is an industry standard that establishes specifications for cables and connectors and protocols for connection, communication and power supply (Interface (computing), interfacing) between computers, peripherals and ...

USB
bandwidth is not required and cable-free connection desired. * Sending small advertisements from Bluetooth-enabled advertising hoardings to other, discoverable, Bluetooth devices. * Wireless bridge between two Industrial Ethernet (e.g.,
PROFINET Profinet (usually styled as PROFINET, as a portmanteau for Process Field Net) is an industry technical standard for data communication over Industrial Ethernet, designed for collecting data from, and controlling equipment in Automation#Industrial a ...
) networks. * Seventh and eighth generation
game consoles A video game console is an electronic or computer A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations automatically. Modern computers can perform generic sets of operations known as C ...
such as
Nintendo is a Japanese multinational Multinational may refer to: * Multinational corporation, a corporate organization operating in multiple countries * Multinational force, a military body from multiple countries * Multinational state, a sovereign s ...

Nintendo
's
Wii The Wii ( ) is a home video game console A home video game console is a video game console that is designed to be connected to a display device, such as a television, and an external power source as to play video games. Home consoles ar ...

Wii
, and
Sony , commonly known as Sony and stylized as SONY, is a Japanese multinational Multinational may refer to: * Multinational corporation, a corporate organization operating in multiple countries * Multinational force, a military body from multi ...

Sony
's
PlayStation 3 The PlayStation 3 (PS3) is a home video game console developed by Sony Computer Entertainment. It is the successor to PlayStation 2, and is part of the PlayStation brand of consoles. It was first released on November 11, 2006 in Japan, Novem ...
use Bluetooth for their respective wireless controllers. * Dial-up internet access on personal computers or PDAs using a data-capable mobile phone as a wireless modem. * Short-range transmission of health sensor data from medical devices to mobile phone, set-top box or dedicated
telehealth Telehealth is the distribution of Health care, health-related services and information via electronic information and Telecommunication, telecommunication technologies. It allows long-distance patient and clinician contact, care, advice, reminders, ...
devices. * Allowing a
DECT#REDIRECT Digital enhanced cordless telecommunications {{Redirect category shell, {{R from move ...
phone to ring and answer calls on behalf of a nearby mobile phone. * Real-time location systems (RTLS) are used to track and identify the location of objects in real time using "Nodes" or "tags" attached to, or embedded in, the objects tracked, and "Readers" that receive and process the wireless signals from these tags to determine their locations. * Personal security application on mobile phones for prevention of theft or loss of items. The protected item has a Bluetooth marker (e.g., a tag) that is in constant communication with the phone. If the connection is broken (the marker is out of range of the phone) then an alarm is raised. This can also be used as a
man overboard "Man overboard!" is an exclamation given aboard a vessel to indicate that a member of the crew or a passenger has fallen off of the ship into the water and is in need of immediate rescue. Whoever sees the person's fall is to shout, "Man overboar ...
alarm. A product using this technology has been available since 2009. *
Calgary Calgary ( ) is a city in the western provinces and territories of Canada, Canadian province of Alberta. With a population of 1,239,220, Calgary is the List of cities in Alberta#List, most populous city in Alberta, and the List of the largest mu ...

Calgary
,
Alberta ("Strong and free") , image_map = Alberta in Canada 2.svg , Label_map = yes , coordinates = , official_lang = English , capital = Edmonton Edmonton () is the capital ci ...

Alberta
, Canada's Roads Traffic division uses data collected from travelers' Bluetooth devices to predict travel times and road congestion for motorists. * Wireless transmission of audio (a more reliable alternative to FM transmitters) * Live video streaming to the visual cortical implant device by Nabeel Fattah in Newcastle university 2017. * Connection of
motion controller Wii Remote with original strap. In video game A video game is an electronic game that involves interaction with a user interface or input device such as a joystick, game controller, controller, computer keyboard, keyboard, or motion sensing ...
s to a PC when using VR headsets


Bluetooth vs Wi-Fi (IEEE 802.11)

Bluetooth and
Wi-Fi Wi-Fi () is a family of wireless network Communication protocol, protocols, based on the IEEE 802.11 family of standards, which are commonly used for Wireless LAN, local area networking of devices and Internet access, allowing nearby digital de ...

Wi-Fi
(Wi-Fi is the brand name for products using
IEEE 802.11 IEEE 802.11 is part of the IEEE 802 IEEE 802 is a family of Institute of Electrical and Electronics Engineers The Institute of Electrical and Electronics Engineers (IEEE) is a professional association for electronic engineering and electri ...
standards) have some similar applications: setting up networks, printing, or transferring files. Wi-Fi is intended as a replacement for high-speed cabling for general
local area network A local area network (LAN) is a computer network that interconnects computers within a limited area such as a residence, school, laboratory, university campus or office building. By contrast, a wide area network (WAN) not only covers a larger ...
access in work areas or home. This category of applications is sometimes called
wireless local area network A wireless LAN (WLAN) is a wireless computer network that links two or more devices using wireless communication to form a local area network (LAN) within a limited area such as a home, school, computer laboratory, campus, or office building. ...
s (WLAN). Bluetooth was intended for portable equipment and its applications. The category of applications is outlined as the wireless
personal area network A personal area network (PAN) is a computer network A computer network is a group of computers that use a set of common communication protocols over digital signal, digital interconnections for the purpose of sharing resources located on or p ...
(WPAN). Bluetooth is a replacement for cabling in various personally carried applications in any setting and also works for fixed location applications such as smart energy functionality in the home (thermostats, etc.). Wi-Fi and Bluetooth are to some extent complementary in their applications and usage. Wi-Fi is usually access point-centered, with an asymmetrical client-server connection with all traffic routed through the access point, while Bluetooth is usually symmetrical, between two Bluetooth devices. Bluetooth serves well in simple applications where two devices need to connect with a minimal configuration like a button press, as in headsets and remote controls, while Wi-Fi suits better in applications where some degree of client configuration is possible and high speeds are required, especially for network access through an access node. However, Bluetooth access points do exist, and ad hoc connections are possible with Wi-Fi though not as simply as with Bluetooth.
Wi-Fi DirectWi-Fi Direct (formerly Wi-Fi Peer-to-Peer) is a Wi-Fi Wi-Fi () is a family of wireless network protocols, based on the IEEE 802.11 family of standards, which are commonly used for local area network A local area network (LAN) is a comput ...

Wi-Fi Direct
was recently developed to add a more Bluetooth-like ad hoc functionality to Wi-Fi.


Devices

Bluetooth exists in numerous products such as telephones,
speakers Speaker may refer to: Roles * Speaker (politics), the presiding officer in a legislative assembly * Public speaker, one who gives a speech or lecture * A person producing speech, sometimes also called a speaker-hearer Electronics * Loudspeaker, a ...
, tablets, media players, robotics systems, laptops, and console gaming equipment as well as some high definition headsets,
modem A modulator-demodulator, or simply a modem, is a hardware device that converts data from a digital format, intended for communication directly between devices with specialized wiring, into one suitable for a transmission medium such as telep ...

modem
s,
hearing aid A hearing aid is a device designed to improve hearing by making sound audible to a person with hearing loss Hearing loss is a partial or total inability to Hearing, hear. Hearing loss may be present at birth or acquired at any time afterwards. ...
s and even watches. Given the variety of devices which use the Bluetooth, coupled with the contemporary deprecation of headphone
jack Jack may refer to: Places * Jack, Alabama Jack is an unincorporated community File:Entering Heinola, Minnesota.jpg, Sign at Heinola, Minnesota, Heinola, an unincorporated community in Otter Tail County, Minnesota An unincorporated area is a re ...
s by Apple, Google, and other companies, and the lack of regulation by the FCC, the technology is prone to interference. Nonetheless Bluetooth is useful when transferring information between two or more devices that are near each other in low-bandwidth situations. Bluetooth is commonly used to transfer sound data with telephones (i.e., with a Bluetooth headset) or byte data with hand-held computers (transferring files). Bluetooth protocols simplify the discovery and setup of services between devices. Bluetooth devices can advertise all of the services they provide. This makes using services easier, because more of the security,
network address A network address is an identifier for a node In general, a node is a localized swelling (a "knot A knot is an intentional complication in Rope, cordage which may be practical or decorative, or both. Practical knots are classified by function, ...
and permission configuration can be automated than with many other network types.


Computer requirements

A personal computer that does not have embedded Bluetooth can use a Bluetooth adapter that enables the PC to communicate with Bluetooth devices. While some
desktop computer A desktop computer is a personal computer File:Crystal Project computer.png, upright=0.9, An artist's depiction of a 2000s-era desktop-style personal computer, which includes a metal case with the computing components, a display monitor and ...
s and most recent laptops come with a built-in Bluetooth radio, others require an external adapter, typically in the form of a small USB "
dongle A dongle is a small piece of computer hardware that connects to a port The Porticciolo del Cedas port in Barcola The thumb is the first digit of the hand, next to the index finger. When a person is standing in the medical anatomical position ...

dongle
." Unlike its predecessor,
IrDA The Infrared Data Association (IrDA) is an industry-driven interest group that was founded in 1994 by around 50 companies. IrDA provides specifications for a complete set of protocols for wireless infrared communications, and the name "IrDA" also r ...
, which requires a separate adapter for each device, Bluetooth lets multiple devices communicate with a computer over a single adapter.


Operating system implementation

For
Microsoft Microsoft Corporation is an American multinational corporation, multinational technology company with headquarters in Redmond, Washington. It develops, manufactures, licenses, supports, and sells Software, computer software, consumer electroni ...

Microsoft
platforms, Windows XP Service Pack 2 and SP3 releases work natively with Bluetooth v1.1, v2.0 and v2.0+EDR. Previous versions required users to install their Bluetooth adapter's own drivers, which were not directly supported by Microsoft. Microsoft's own Bluetooth dongles (packaged with their Bluetooth computer devices) have no external drivers and thus require at least Windows XP Service Pack 2. Windows Vista RTM/SP1 with the Feature Pack for Wireless or Windows Vista SP2 work with Bluetooth v2.1+EDR. Windows 7 works with Bluetooth v2.1+EDR and Extended Inquiry Response (EIR). The Windows XP and Windows Vista/Windows 7 Bluetooth stacks support the following Bluetooth profiles natively: PAN, SPP,
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, HID, HCRP. The Windows XP stack can be replaced by a third party stack that supports more profiles or newer Bluetooth versions. The Windows Vista/Windows 7 Bluetooth stack supports vendor-supplied additional profiles without requiring that the Microsoft stack be replaced. It is generally recommended to install the latest vendor driver and its associated stack to be able to use the Bluetooth device at its fullest extent.
Apple An apple is an edible fruit produced by an apple tree (''Malus domestica''). Apple fruit tree, trees are agriculture, cultivated worldwide and are the most widely grown species in the genus ''Malus''. The tree originated in Central Asia, wher ...
products have worked with Bluetooth since Mac OSX v10.2, which was released in 2002.
Linux Linux ( or ) is a family of free and open-source software, open-source Unix-like operating systems based on the Linux kernel, an Kernel (computing), operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is t ...

Linux
has two popular s, BlueZ and Fluoride. The BlueZ stack is included with most Linux kernels and was originally developed by
Qualcomm Qualcomm () is an American multinational corporation headquartered in San Diego, California, and Delaware General Corporation Law, incorporated in Delaware. It creates semiconductors, software, and services related to wireless technology. It own ...

Qualcomm
. Fluoride, earlier known as Bluedroid is included in Android OS and was originally developed by
Broadcom Broadcom Inc. is an American designer, developer, manufacturer and global supplier of a wide range of semiconductor and infrastructure software products. Broadcom's product offerings serve the data center, networking, software, broadband, wirele ...

Broadcom
. There is also Affix stack, developed by
Nokia Nokia Corporation (natively Nokia Oyj, referred to as Nokia; stylized as NOKIA) is a Finnish multinational corporation, multinational telecommunications, information technology company, information technology, and consumer electronics company, ...

Nokia
. It was once popular, but has not been updated since 2005.
FreeBSD FreeBSD is a free and open-source Free and open-source software (FOSS) is software Software is a collection of Instruction (computer science), instructions and data (computing), data that tell a computer how to work. This is in contrast ...

FreeBSD
has included Bluetooth since its v5.0 release, implemented through netgraph. NetBSD has included Bluetooth since its v4.0 release. Its Bluetooth stack was ported to OpenBSD as well, however OpenBSD later removed it as unmaintained. DragonFly BSD has had NetBSD's Bluetooth implementation since 1.11 (2008). A netgraph-based implementation from
FreeBSD FreeBSD is a free and open-source Free and open-source software (FOSS) is software Software is a collection of Instruction (computer science), instructions and data (computing), data that tell a computer how to work. This is in contrast ...

FreeBSD
has also been available in the tree, possibly disabled until 2014-11-15, and may require more work.


Specifications and features

The specifications were formalized by the
Bluetooth Special Interest Group The Bluetooth Special Interest Group (Bluetooth SIG) is the standards organization A standards organization, standards body, standards developing organization (SDO), or standards setting organization (SSO) is an organization whose primary funct ...
(SIG) and formally announced on 20 May 1998. Today it has a membership of over 30,000 companies worldwide. It was established by Ericsson, IBM,
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,
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Nokia
and Toshiba, and later joined by many other companies. All versions of the Bluetooth standards support Backward compatibility, downward compatibility. That lets the latest standard cover all older versions. The Bluetooth Core Specification Working Group (CSWG) produces mainly 4 kinds of specifications: * The Bluetooth Core Specification, release cycle is typically a few years in between * Core Specification Addendum (CSA), release cycle can be as tight as a few times per year * Core Specification Supplements (CSS), can be released very quickly * Errata (Available with a user account
Errata login


Bluetooth 1.0 and 1.0B

Versions 1.0 and 1.0B had many problems, and manufacturers had difficulty making their products interoperable. Versions 1.0 and 1.0B also included mandatory Bluetooth hardware device address (BD_ADDR) transmission in the Connecting process (rendering anonymity impossible at the protocol level), which was a major setback for certain services planned for use in Bluetooth environments.


Bluetooth 1.1

* Ratified as IEEE 802.15#Task group 1 (WPAN/Bluetooth), IEEE Standard 802.15.1–2002 * Many errors found in the v1.0B specifications were fixed. * Added possibility of non-encrypted channels. * Received Signal Strength Indicator (RSSI).


Bluetooth 1.2

Major enhancements include: * Faster Connection and Discovery * ''Adaptive
frequency-hopping spread spectrum Frequency-hopping spread spectrum (FHSS) is a method of transmitting radio signals by rapidly changing the carrier frequency among many distinct frequencies occupying a large spectral band. The changes are controlled by a code known to both tra ...
(AFH)'', which improves resistance to radio frequency interference by avoiding the use of crowded frequencies in the hopping sequence. * Higher transmission speeds in practice than in v1.1, up to 721 kbit/s. * Extended Synchronous Connections (eSCO), which improve voice quality of audio links by allowing retransmissions of corrupted packets, and may optionally increase audio latency to provide better concurrent data transfer. * Bluetooth protocols#Host/controller interface (HCI), Host Controller Interface (HCI) operation with three-wire Universal asynchronous receiver/transmitter, UART. * Ratified as IEEE 802.15#Task group 1 (WPAN/Bluetooth), IEEE Standard 802.15.1–2005 * Introduced Flow Control and Retransmission Modes for L2CAP.


Bluetooth 2.0 + EDR

This version of the Bluetooth Core Specification was released before 2005. The main difference is the introduction of an Enhanced Data Rate (EDR) for faster Bit rate, data transfer. The bit rate of EDR is 3Mbit/s, although the maximum data transfer rate (allowing for inter-packet time and acknowledgements) is 2.1Mbit/s. EDR uses a combination of Gaussian frequency-shift keying, GFSK and phase-shift keying modulation (PSK) with two variants, π/4- and 8-DPSK. EDR can provide a lower power consumption through a reduced duty cycle. The specification is published as ''Bluetooth v2.0 + EDR'', which implies that EDR is an optional feature. Aside from EDR, the v2.0 specification contains other minor improvements, and products may claim compliance to "Bluetooth v2.0" without supporting the higher data rate. At least one commercial device states "Bluetooth v2.0 without EDR" on its data sheet.


Bluetooth 2.1 + EDR

Bluetooth Core Specification Version 2.1 + EDR was adopted by the Bluetooth SIG on 26 July 2007. The headline feature of v2.1 is #Pairing, secure simple pairing (SSP): this improves the pairing experience for Bluetooth devices, while increasing the use and strength of security. Version 2.1 allows various other improvements, including ''extended inquiry response'' (EIR), which provides more information during the inquiry procedure to allow better filtering of devices before connection; and sniff subrating, which reduces the power consumption in low-power mode.


Bluetooth 3.0 + HS

Version 3.0 + HS of the Bluetooth Core Specification was adopted by the Bluetooth SIG on 21 April 2009. Bluetooth v3.0 + HS provides theoretical data transfer speeds of up to 24 Mbit/s, though not over the Bluetooth link itself. Instead, the Bluetooth link is used for negotiation and establishment, and the high data rate traffic is carried over a colocated IEEE 802.11, 802.11 link. The main new feature is AMP (Alternative MAC/PHY), the addition of IEEE 802.11, 802.11 as a high-speed transport. The high-speed part of the specification is not mandatory, and hence only devices that display the "+HS" logo actually support Bluetooth over 802.11 high-speed data transfer. A Bluetooth v3.0 device without the "+HS" suffix is only required to support features introduced in Core Specification Version 3.0 or earlier Core Specification Addendum 1. ; #L2CAP, L2CAP Enhanced modes: Enhanced Retransmission Mode (ERTM) implements reliable L2CAP channel, while Streaming Mode (SM) implements unreliable channel with no retransmission or flow control. Introduced in Core Specification Addendum 1. ; Alternative MAC/PHY: Enables the use of alternative Media Access Control, MAC and PHYs for transporting Bluetooth profile data. The Bluetooth radio is still used for device discovery, initial connection and profile configuration. However, when large quantities of data must be sent, the high-speed alternative MAC PHY 802.11 (typically associated with Wi-Fi) transports the data. This means that Bluetooth uses proven low power connection models when the system is idle, and the faster radio when it must send large quantities of data. AMP links require enhanced L2CAP modes. ; Unicast Connectionless Data: Permits sending service data without establishing an explicit L2CAP channel. It is intended for use by applications that require low latency between user action and reconnection/transmission of data. This is only appropriate for small amounts of data. ; Enhanced Power Control: Updates the power control feature to remove the open loop power control, and also to clarify ambiguities in power control introduced by the new modulation schemes added for EDR. Enhanced power control removes the ambiguities by specifying the behavior that is expected. The feature also adds closed loop power control, meaning RSSI filtering can start as the response is received. Additionally, a "go straight to maximum power" request has been introduced. This is expected to deal with the headset link loss issue typically observed when a user puts their phone into a pocket on the opposite side to the headset.


Ultra-wideband

The high-speed (AMP) feature of Bluetooth v3.0 was originally intended for Ultra-wideband, UWB, but the WiMedia Alliance, the body responsible for the flavor of UWB intended for Bluetooth, announced in March 2009 that it was disbanding, and ultimately UWB was omitted from the Core v3.0 specification. On 16 March 2009, the WiMedia Alliance announced it was entering into technology transfer agreements for the WiMedia Ultra-wideband (UWB) specifications. WiMedia has transferred all current and future specifications, including work on future high-speed and power-optimized implementations, to the Bluetooth Special Interest Group (SIG), Wireless USB Promoter Group and the USB Implementers Forum. After successful completion of the technology transfer, marketing, and related administrative items, the WiMedia Alliance ceased operations. In October 2009 the
Bluetooth Special Interest Group The Bluetooth Special Interest Group (Bluetooth SIG) is the standards organization A standards organization, standards body, standards developing organization (SDO), or standards setting organization (SSO) is an organization whose primary funct ...
suspended development of UWB as part of the alternative MAC/PHY, Bluetooth v3.0 + HS solution. A small, but significant, number of former WiMedia Alliance, WiMedia members had not and would not sign up to the necessary agreements for the intellectual property, IP transfer. The Bluetooth SIG is now in the process of evaluating other options for its longer term roadmap.


Bluetooth 4.0

The Bluetooth SIG completed the Bluetooth Core Specification version 4.0 (called Bluetooth Smart) and has been adopted . It includes ''Classic Bluetooth'', ''Bluetooth high speed'' and '' Bluetooth Low Energy'' (BLE) protocols. Bluetooth high speed is based on Wi-Fi, and Classic Bluetooth consists of legacy Bluetooth protocols. Bluetooth Low Energy, previously known as Wibree, is a subset of Bluetooth v4.0 with an entirely new protocol stack for rapid build-up of simple links. As an alternative to the Bluetooth standard protocols that were introduced in Bluetooth v1.0 to v3.0, it is aimed at very low power applications powered by a Button cell, coin cell. Chip designs allow for two types of implementation, dual-mode, single-mode and enhanced past versions. The provisional names ''Wibree'' and ''Bluetooth ULP'' (Ultra Low Power) were abandoned and the BLE name was used for a while. In late 2011, new logos "Bluetooth Smart Ready" for hosts and "Bluetooth Smart" for sensors were introduced as the general-public face of BLE. Compared to ''Classic Bluetooth'', Bluetooth Low Energy is intended to provide considerably reduced power consumption and cost while maintaining a #Radio interface, similar communication range. In terms of lengthening the battery life of Bluetooth devices, represents a significant progression. * In a single-mode implementation, only the low energy protocol stack is implemented. Dialog Semiconductor, STMicroelectronics, AMICCOM, CSR plc, CSR, Nordic Semiconductor and Texas Instruments have released single mode Bluetooth Low Energy solutions. * In a dual-mode implementation, Bluetooth Smart functionality is integrated into an existing Classic Bluetooth controller. , the following semiconductor companies have announced the availability of chips meeting the standard: Qualcomm Atheros, Qualcomm-Atheros, CSR plc, CSR,
Broadcom Broadcom Inc. is an American designer, developer, manufacturer and global supplier of a wide range of semiconductor and infrastructure software products. Broadcom's product offerings serve the data center, networking, software, broadband, wirele ...

Broadcom
and Texas Instruments. The compliant architecture shares all of Classic Bluetooth's existing radio and functionality resulting in a negligible cost increase compared to Classic Bluetooth. Cost-reduced single-mode chips, which enable highly integrated and compact devices, feature a lightweight Link Layer providing ultra-low power idle mode operation, simple device discovery, and reliable point-to-multipoint data transfer with advanced power-save and secure encrypted connections at the lowest possible cost. General improvements in version 4.0 include the changes necessary to facilitate BLE modes, as well the Generic Attribute Profile (GATT) and Security Manager (SM) services with Advanced Encryption Standard, AES Encryption. Core Specification Addendum 2 was unveiled in December 2011; it contains improvements to the audio Host Controller Interface and to the High Speed (802.11) Protocol Adaptation Layer. Core Specification Addendum 3 revision 2 has an adoption date of 24 July 2012. Core Specification Addendum 4 has an adoption date of 12 February 2013.


Bluetooth 4.1

The Bluetooth SIG announced formal adoption of the Bluetooth v4.1 specification on 4 December 2013. This specification is an incremental software update to Bluetooth Specification v4.0, and not a hardware update. The update incorporates Bluetooth Core Specification Addenda (CSA 1, 2, 3 & 4) and adds new features that improve consumer usability. These include increased co-existence support for LTE, bulk data exchange rates—and aid developer innovation by allowing devices to support multiple roles simultaneously. New features of this specification include: * Mobile Wireless Service Coexistence Signaling * Train Nudging and Generalized Interlaced Scanning * Low Duty Cycle Directed Advertising * L2CAP Connection Oriented and Dedicated Channels with Credit-Based Flow Control * Dual Mode and Topology * LE Link Layer Topology * 802.11n PAL * Audio Architecture Updates for Wide Band Speech * Fast Data Advertising Interval * Limited Discovery Time Notice that some features were already available in a Core Specification Addendum (CSA) before the release of v4.1.


Bluetooth 4.2

Released on 2 December 2014, it introduces features for the Internet of Things. The major areas of improvement are: * Bluetooth Low Energy, Low Energy Cryptographic protocol, Secure Connection with Data packet, Data Packet Length Extension * Link layer, Link Layer Privacy with Extended Scanner Filter Policies * Internet Protocol Support Profile (IPSP) IPv6, version 6 ready for Bluetooth Low Energy, Bluetooth Smart Internet of things, things to support connected home Older Bluetooth hardware may receive 4.2 features such as Data Packet Length Extension and improved privacy via firmware updates.


Bluetooth 5

The Bluetooth SIG released Bluetooth 5 on 6 December 2016. Its new features are mainly focused on new Internet of Things technology. Sony was the first to announce Bluetooth 5.0 support with its Xperia XZ Premium in Feb 2017 during the Mobile World Congress 2017. The Samsung Galaxy S8 launched with Bluetooth 5 support in April 2017. In September 2017, the iPhone 8, 8 Plus and iPhone X launched with Bluetooth 5 support as well.
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also integrated Bluetooth 5 in its new HomePod offering released on 9 February 2018. Marketing drops the point number; so that it is just "Bluetooth 5" (unlike Bluetooth 4.0); the change is for the sake of "Simplifying our marketing, communicating user benefits more effectively and making it easier to signal significant technology updates to the market." Bluetooth 5 provides, for , options that can double the speed (2Mbit/s burst) at the expense of range, or up to fourfold the range at the expense of data rate. The increase in transmissions could be important for Internet of Things devices, where many nodes connect throughout a whole house. Bluetooth 5 increases capacity of connectionless services such as location-relevant navigation of low-energy Bluetooth connections. The major areas of improvement are: * Slot Availability Mask (SAM) * 2 Mbit/s PHY for * LE Long Range * High Duty Cycle Non-Connectable Advertising * LE Advertising Extensions * LE Channel Selection Algorithm #2 Features Added in CSA5 – Integrated in v5.0: * Higher Output Power The following features were removed in this version of the specification: * Park State


Bluetooth 5.1

The Bluetooth SIG presented Bluetooth 5.1 on 21 January 2019. The major areas of improvement are: * Angle of Arrival (AoA) and Angle of Departure (AoD) which are used for locating and tracking of devices * Advertising Channel Index * GATT Caching * Minor Enhancements batch 1: ** HCI support for debug keys in LE Secure Connections ** Sleep clock accuracy update mechanism ** ADI field in scan response data ** Interaction between QoS and Flow Specification ** Block Host channel classification for secondary advertising ** Allow the SID to appear in scan response reports ** Specify the behavior when rules are violated * Periodic Advertising Sync Transfer Features Added in Core Specification Addendum (CSA) 6 – Integrated in v5.1: * Models * Bluetooth mesh#Mesh models, Mesh-based model hierarchy The following features were removed in this version of the specification: * Unit keys


Bluetooth 5.2

On 31 December 2019, the Bluetooth SIG published the Bluetooth Core Specification Version 5.2. The new specification adds new features: * LE Audio: Announced in January 2020 at Consumer Electronics Show, CES by the Bluetooth Special Interest Group, Bluetooth SIG, LE Audio will run on the Bluetooth Low Energy radio lowering battery consumption, and allow the protocol to carry sound and add features such as one set of headphones connecting to multiple audio sources or multiple headphones connecting to one source. It uses a new LC3 (codec), LC3 codec. BLE Audio will also add support for hearing aids. * Enhanced Attribute Protocol (EATT), an improved version of the Attribute Protocol (ATT) * LE Power Control * LE Isochronous Channels


Technical information


Architecture


Software

Seeking to extend the compatibility of Bluetooth devices, the devices that adhere to the standard use an interface called HCI (Host Controller Interface) between the host device (e.g. laptop, phone) and the Bluetooth device (e.g. Bluetooth wireless headset). High-level protocols such as the SDP (Protocol used to find other Bluetooth devices within the communication range, also responsible for detecting the function of devices in range), RFCOMM (Protocol used to emulate serial port connections) and TCS (Telephony control protocol) interact with the baseband controller through the L2CAP Protocol (Logical Link Control and Adaptation Protocol). The L2CAP protocol is responsible for the segmentation and reassembly of the packets.


Hardware

The hardware that makes up the Bluetooth device is made up of, logically, two parts; which may or may not be physically separate. A radio device, responsible for modulating and transmitting the signal; and a digital controller. The digital controller is likely a CPU, one of whose functions is to run a Link Controller; and interfaces with the host device; but some functions may be delegated to hardware. The Link Controller is responsible for the processing of the baseband and the management of ARQ and physical layer FEC protocols. In addition, it handles the transfer functions (both asynchronous and synchronous), audio coding (e.g. SBC (codec)) and data encryption. The CPU of the device is responsible for attending the instructions related to Bluetooth of the host device, in order to simplify its operation. To do this, the CPU runs software called Link Manager that has the function of communicating with other devices through the LMP protocol. A Bluetooth device is a short-range device, short-range
wireless Wireless communication (or just wireless, when the context allows) is the telecommunication, transfer of information between two or more points that do not use an electrical conductor as a medium by which to perform the transfer. The most common ...

wireless
device. Bluetooth devices are semiconductor device fabrication, fabricated on RF CMOS
integrated circuit An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuits on one small flat piece (or "chip") of semiconductor material, usually silicon. Transistor count, Larg ...

integrated circuit
(RF circuit) chips.


Bluetooth protocol stack

Bluetooth is defined as a layer protocol architecture consisting of core protocols, cable replacement protocols, telephony control protocols, and adopted protocols.Stallings, William. (2005). ''Wireless communications & networks.'=' Upper Saddle River, NJ: Pearson Prentice Hall.'' Mandatory protocols for all Bluetooth stacks are LMP, L2CAP and SDP. In addition, devices that communicate with Bluetooth almost universally can use these protocols: Bluetooth protocols#Host Controller Interface (HCI), HCI and RFCOMM.


Link Manager

The Link Manager (LM) is the system that manages establishing the connection between devices. It is responsible for the establishment, authentication and configuration of the link. The Link Manager locates other managers and communicates with them via the management protocol of the LMP link. To perform its function as a service provider, the LM uses the services included in the Link Controller (LC). The Link Manager Protocol basically consists of several PDUs (Protocol Data Units) that are sent from one device to another. The following is a list of supported services: * Transmission and reception of data. * Name request * Request of the link addresses. * Establishment of the connection. * Authentication. * Negotiation of link mode and connection establishment.


Host Controller Interface

The Host Controller Interface provides a command interface for the controller and for the link manager, which allows access to the hardware status and control registers. This interface provides an access layer for all Bluetooth devices. The HCI layer of the machine exchanges commands and data with the HCI firmware present in the Bluetooth device. One of the most important HCI tasks that must be performed is the automatic discovery of other Bluetooth devices that are within the coverage radius.


Logical Link Control and Adaptation Protocol

The ''Logical Link Control and Adaptation Protocol'' (L2CAP) is used to multiplex multiple logical connections between two devices using different higher level protocols. Provides segmentation and reassembly of on-air packets. In ''Basic'' mode, L2CAP provides packets with a payload configurable up to 64 kB, with 672 bytes as the default Maximum transmission unit, MTU, and 48 bytes as the minimum mandatory supported MTU. In ''Retransmission and Flow Control'' modes, L2CAP can be configured either for isochronous data or reliable data per channel by performing retransmissions and CRC checks. Bluetooth Core Specification Addendum 1 adds two additional L2CAP modes to the core specification. These modes effectively deprecate original Retransmission and Flow Control modes: ; Enhanced Retransmission Mode (ERTM): This mode is an improved version of the original retransmission mode. This mode provides a reliable L2CAP channel. ; Streaming Mode (SM): This is a very simple mode, with no retransmission or flow control. This mode provides an unreliable L2CAP channel. Reliability in any of these modes is optionally and/or additionally guaranteed by the lower layer Bluetooth BDR/EDR air interface by configuring the number of retransmissions and flush timeout (time after which the radio flushes packets). In-order sequencing is guaranteed by the lower layer. Only L2CAP channels configured in ERTM or SM may be operated over AMP logical links.


Service Discovery Protocol

The ''Service Discovery Protocol'' (SDP) allows a device to discover services offered by other devices, and their associated parameters. For example, when you use a mobile phone with a Bluetooth headset, the phone uses SDP to determine which Bluetooth profiles the headset can use (Headset Profile, Hands Free Profile (HFP), Advanced Audio Distribution Profile, Advanced Audio Distribution Profile (A2DP) etc.) and the protocol multiplexer settings needed for the phone to connect to the headset using each of them. Each service is identified by a Universally Unique Identifier (UUID), with official services (Bluetooth profiles) assigned a short form UUID (16 bits rather than the full 128).


Radio Frequency Communications

''Radio Frequency Communications'' (RFCOMM) is a cable replacement protocol used for generating a virtual serial data stream. RFCOMM provides for binary data transport and emulates EIA-232 (formerly RS-232) control signals over the Bluetooth baseband layer, i.e., it is a serial port emulation. RFCOMM provides a simple, reliable, data stream to the user, similar to TCP. It is used directly by many telephony related profiles as a carrier for AT commands, as well as being a transport layer for OBEX over Bluetooth. Many Bluetooth applications use RFCOMM because of its widespread support and publicly available API on most operating systems. Additionally, applications that used a serial port to communicate can be quickly ported to use RFCOMM.


Bluetooth Network Encapsulation Protocol

The ''Bluetooth Network Encapsulation Protocol'' (BNEP) is used for transferring another protocol stack's data via an L2CAP channel. Its main purpose is the transmission of IP packets in the Personal Area Networking Profile. BNEP performs a similar function to Subnetwork Access Protocol, SNAP in Wireless LAN.


Audio/Video Control Transport Protocol

The ''Audio/Video Control Transport Protocol'' (AVCTP) is used by the remote control profile to transfer AV/C commands over an L2CAP channel. The music control buttons on a stereo headset use this protocol to control the music player.


Audio/Video Distribution Transport Protocol

The ''Audio/Video Distribution Transport Protocol'' (AVDTP) is used by the advanced audio distribution (A2DP) profile to stream music to stereo headsets over an List of Bluetooth protocols#Logical link control and adaptation protocol (L2CAP), L2CAP channel intended for video distribution profile in the Bluetooth transmission.


Telephony Control Protocol

The ''Telephony Control Protocol– Binary'' (TCS BIN) is the bit-oriented protocol that defines the call control signaling for the establishment of voice and data calls between Bluetooth devices. Additionally, "TCS BIN defines mobility management procedures for handling groups of Bluetooth TCS devices." TCS-BIN is only used by the cordless telephony profile, which failed to attract implementers. As such it is only of historical interest.


Adopted protocols

Adopted protocols are defined by other standards-making organizations and incorporated into Bluetooth's protocol stack, allowing Bluetooth to code protocols only when necessary. The adopted protocols include: ;Point-to-Point Protocol (PPP): Internet standard protocol for transporting IP datagrams over a point-to-point link. ;TCP/IP/UDP: Foundation Protocols for TCP/IP protocol suite ;OBject EXchange, Object Exchange Protocol (OBEX): Session-layer protocol for the exchange of objects, providing a model for object and operation representation ;Wireless Application Protocol, Wireless Application Environment/Wireless Application Protocol (WAE/WAP): WAE specifies an application framework for wireless devices and WAP is an open standard to provide mobile users access to telephony and information services.


Baseband error correction

Depending on packet type, individual packets may be protected by error correction, either 1/3 rate forward error correction (FEC) or 2/3 rate. In addition, packets with CRC will be retransmitted until acknowledged by automatic repeat request (ARQ).


Setting up connections

Any Bluetooth device in ''discoverable mode'' transmits the following information on demand: * Device name * Device class * List of services * Technical information (for example: device features, manufacturer, Bluetooth specification used, clock offset) Any device may perform an inquiry to find other devices to connect to, and any device can be configured to respond to such inquiries. However, if the device trying to connect knows the address of the device, it always responds to direct connection requests and transmits the information shown in the list above if requested. Use of a device's services may require pairing or acceptance by its owner, but the connection itself can be initiated by any device and held until it goes out of range. Some devices can be connected to only one device at a time, and connecting to them prevents them from connecting to other devices and appearing in inquiries until they disconnect from the other device. Every device has a MAC address, unique 48-bit address. However, these addresses are generally not shown in inquiries. Instead, friendly Bluetooth names are used, which can be set by the user. This name appears when another user scans for devices and in lists of paired devices. Most cellular phones have the Bluetooth name set to the manufacturer and model of the phone by default. Most cellular phones and laptops show only the Bluetooth names and special programs are required to get additional information about remote devices. This can be confusing as, for example, there could be several cellular phones in range named Sony Ericsson T610, T610 (see Bluejacking).


Pairing and bonding


Motivation

Many services offered over Bluetooth can expose private data or let a connecting party control the Bluetooth device. Security reasons make it necessary to recognize specific devices, and thus enable control over which devices can connect to a given Bluetooth device. At the same time, it is useful for Bluetooth devices to be able to establish a connection without user intervention (for example, as soon as in range). To resolve this conflict, Bluetooth uses a process called ''bonding'', and a bond is generated through a process called ''pairing''. The pairing process is triggered either by a specific request from a user to generate a bond (for example, the user explicitly requests to "Add a Bluetooth device"), or it is triggered automatically when connecting to a service where (for the first time) the identity of a device is required for security purposes. These two cases are referred to as dedicated bonding and general bonding respectively. Pairing often involves some level of user interaction. This user interaction confirms the identity of the devices. When pairing completes, a bond forms between the two devices, enabling those two devices to connect in the future without repeating the pairing process to confirm device identities. When desired, the user can remove the bonding relationship.


Implementation

During pairing, the two devices establish a relationship by creating a shared secret known as a ''link key''. If both devices store the same link key, they are said to be ''paired'' or ''bonded''. A device that wants to communicate only with a bonded device can cryptography, cryptographically authentication, authenticate the identity of the other device, ensuring it is the same device it previously paired with. Once a link key is generated, an authenticated Asynchronous Connection-Less (ACL) link between the devices may be encryption, encrypted to protect exchanged data against eavesdropping. Users can delete link keys from either device, which removes the bond between the devices—so it is possible for one device to have a stored link key for a device it is no longer paired with. Bluetooth services generally require either encryption or authentication and as such require pairing before they let a remote device connect. Some services, such as the Object Push Profile, elect not to explicitly require authentication or encryption so that pairing does not interfere with the user experience associated with the service use-cases.


Pairing mechanisms

Pairing mechanisms changed significantly with the introduction of Secure Simple Pairing in Bluetooth v2.1. The following summarizes the pairing mechanisms: * ''Legacy pairing'': This is the only method available in Bluetooth v2.0 and before. Each device must enter a Personal identification number, PIN code; pairing is only successful if both devices enter the same PIN code. Any 16-byte UTF-8 string may be used as a PIN code; however, not all devices may be capable of entering all possible PIN codes. ** ''Limited input devices'': The obvious example of this class of device is a Bluetooth Hands-free headset, which generally have few inputs. These devices usually have a ''fixed PIN'', for example "0000" or "1234", that are hard-coded into the device. ** ''Numeric input devices'': Mobile phones are classic examples of these devices. They allow a user to enter a numeric value up to 16 digits in length. ** ''Alpha-numeric input devices'': PCs and smartphones are examples of these devices. They allow a user to enter full UTF-8 text as a PIN code. If pairing with a less capable device the user must be aware of the input limitations on the other device; there is no mechanism available for a capable device to determine how it should limit the available input a user may use. * ''Secure Simple Pairing'' (SSP): This is required by Bluetooth v2.1, although a Bluetooth v2.1 device may only use legacy pairing to interoperate with a v2.0 or earlier device. Secure Simple Pairing uses a form of public-key cryptography, and some types can help protect against Man-in-the-middle attack, man in the middle, or MITM attacks. SSP has the following authentication mechanisms: ** ''Just works'': As the name implies, this method just works, with no user interaction. However, a device may prompt the user to confirm the pairing process. This method is typically used by headsets with minimal IO capabilities, and is more secure than the fixed PIN mechanism this limited set of devices uses for legacy pairing. This method provides no man-in-the-middle (MITM) protection. ** ''Numeric comparison'': If both devices have a display, and at least one can accept a binary yes/no user input, they may use Numeric Comparison. This method displays a 6-digit numeric code on each device. The user should compare the numbers to ensure they are identical. If the comparison succeeds, the user(s) should confirm pairing on the device(s) that can accept an input. This method provides MITM protection, assuming the user confirms on both devices and actually performs the comparison properly. ** ''Passkey Entry'': This method may be used between a device with a display and a device with numeric keypad entry (such as a keyboard), or two devices with numeric keypad entry. In the first case, the display presents a 6-digit numeric code to the user, who then enters the code on the keypad. In the second case, the user of each device enters the same 6-digit number. Both of these cases provide MITM protection. ** ''Out of band'' (OOB): This method uses an external means of communication, such as near-field communication (NFC) to exchange some information used in the pairing process. Pairing is completed using the Bluetooth radio, but requires information from the OOB mechanism. This provides only the level of MITM protection that is present in the OOB mechanism. SSP is considered simple for the following reasons: * In most cases, it does not require a user to generate a passkey. * For use cases not requiring MITM protection, user interaction can be eliminated. * For ''numeric comparison'', MITM protection can be achieved with a simple equality comparison by the user. * Using OOB with NFC enables pairing when devices simply get close, rather than requiring a lengthy discovery process.


Security concerns

Prior to Bluetooth v2.1, encryption is not required and can be turned off at any time. Moreover, the encryption key is only good for approximately 23.5 hours; using a single encryption key longer than this time allows simple Stream cipher attack, XOR attacks to retrieve the encryption key. * Turning off encryption is required for several normal operations, so it is problematic to detect if encryption is disabled for a valid reason or a security attack. Bluetooth v2.1 addresses this in the following ways: * Encryption is required for all non-SDP (Service Discovery Protocol) connections * A new Encryption Pause and Resume feature is used for all normal operations that require that encryption be disabled. This enables easy identification of normal operation from security attacks. * The encryption key must be refreshed before it expires. Link keys may be stored on the device file system, not on the Bluetooth chip itself. Many Bluetooth chip manufacturers let link keys be stored on the device—however, if the device is removable, this means that the link key moves with the device.


Security


Overview

Bluetooth implements confidentiality, authentication and key (cryptography), key derivation with custom algorithms based on the SAFER, SAFER+ block cipher. Bluetooth key generation is generally based on a Bluetooth PIN, which must be entered into both devices. This procedure might be modified if one of the devices has a fixed PIN (e.g., for headsets or similar devices with a restricted user interface). During pairing, an initialization key or master key is generated, using the E22 algorithm. The E0 (cipher), E0 stream cipher is used for encrypting packets, granting confidentiality, and is based on a shared cryptographic secret, namely a previously generated link key or master key. Those keys, used for subsequent encryption of data sent via the air interface, rely on the Bluetooth PIN, which has been entered into one or both devices. An overview of Bluetooth vulnerabilities exploits was published in 2007 by Andreas Becker. In September 2008, the National Institute of Standards and Technology (NIST) published a Guide to Bluetooth Security as a reference for organizations. It describes Bluetooth security capabilities and how to secure Bluetooth technologies effectively. While Bluetooth has its benefits, it is susceptible to denial-of-service attacks, eavesdropping, man-in-the-middle attacks, message modification, and resource misappropriation. Users and organizations must evaluate their acceptable level of risk and incorporate security into the lifecycle of Bluetooth devices. To help mitigate risks, included in the NIST document are security checklists with guidelines and recommendations for creating and maintaining secure Bluetooth piconets, headsets, and smart card readers. Bluetooth v2.1 – finalized in 2007 with consumer devices first appearing in 2009 – makes significant changes to Bluetooth's security, including pairing. See the #Pairing mechanisms, pairing mechanisms section for more about these changes.


Bluejacking

Bluejacking is the sending of either a picture or a message from one user to an unsuspecting user through Bluetooth wireless technology. Common applications include short messages, e.g., "You've just been bluejacked!" Bluejacking does not involve the removal or alteration of any data from the device. Bluejacking can also involve taking control of a mobile device wirelessly and phoning a premium rate line, owned by the bluejacker. Security advances have alleviated this issue .


History of security concerns


2001–2004

In 2001, Jakobsson and Wetzel from Bell Laboratories discovered flaws in the Bluetooth pairing protocol and also pointed to vulnerabilities in the encryption scheme. In 2003, Ben and Adam Laurie from A.L. Digital Ltd. discovered that serious flaws in some poor implementations of Bluetooth security may lead to disclosure of personal data. In a subsequent experiment, Martin Herfurt from the trifinite.group was able to do a field-trial at the CeBIT fairgrounds, showing the importance of the problem to the world. A new attack called Bluebugging, BlueBug was used for this experiment. In 2004 the first purported computer virus, virus using Bluetooth to spread itself among mobile phones appeared on the Symbian OS. The virus was first described by Kaspersky Lab and requires users to confirm the installation of unknown software before it can propagate. The virus was written as a proof-of-concept by a group of virus writers known as "29A" and sent to anti-virus groups. Thus, it should be regarded as a potential (but not real) security threat to Bluetooth technology or Symbian OS since the virus has never spread outside of this system. In August 2004, a world-record-setting experiment (see also Bluetooth sniping) showed that the range of Class 2 Bluetooth radios could be extended to with directional antennas and signal amplifiers. This poses a potential security threat because it enables attackers to access vulnerable Bluetooth devices from a distance beyond expectation. The attacker must also be able to receive information from the victim to set up a connection. No attack can be made against a Bluetooth device unless the attacker knows its Bluetooth address and which channels to transmit on, although these can be deduced within a few minutes if the device is in use.


2005

In January 2005, a mobile malware worm known as Lasco surfaced. The worm began targeting mobile phones using Symbian OS (S60 (software platform), Series 60 platform) using Bluetooth enabled devices to replicate itself and spread to other devices. The worm is self-installing and begins once the mobile user approves the transfer of the file (Velasco.sis) from another device. Once installed, the worm begins looking for other Bluetooth enabled devices to infect. Additionally, the worm infects other .SIS files on the device, allowing replication to another device through the use of removable media (Secure Digital, CompactFlash, etc.). The worm can render the mobile device unstable. In April 2005, University of Cambridge, Cambridge University security researchers published results of their actual implementation of passive attacks against the Personal identification number, PIN-based pairing between commercial Bluetooth devices. They confirmed that attacks are practicably fast, and the Bluetooth symmetric key establishment method is vulnerable. To rectify this vulnerability, they designed an implementation that showed that stronger, asymmetric key establishment is feasible for certain classes of devices, such as mobile phones. In June 2005, Yaniv Shaked and Avishai Wool published a paper describing both passive and active methods for obtaining the PIN for a Bluetooth link. The passive attack allows a suitably equipped attacker to eavesdrop on communications and spoof if the attacker was present at the time of initial pairing. The active method makes use of a specially constructed message that must be inserted at a specific point in the protocol, to make the master and slave repeat the pairing process. After that, the first method can be used to crack the PIN. This attack's major weakness is that it requires the user of the devices under attack to re-enter the PIN during the attack when the device prompts them to. Also, this active attack probably requires custom hardware, since most commercially available Bluetooth devices are not capable of the timing necessary. In August 2005, police in Cambridgeshire, England, issued warnings about thieves using Bluetooth enabled phones to track other devices left in cars. Police are advising users to ensure that any mobile networking connections are de-activated if laptops and other devices are left in this way.


2006

In April 2006, researchers from Secure Network and F-Secure published a report that warns of the large number of devices left in a visible state, and issued statistics on the spread of various Bluetooth services and the ease of spread of an eventual Bluetooth worm. In October 2006, at the Luxemburgish Hack.lu Security Conference, Kevin Finistere and Thierry Zoller demonstrated and released a remote root shell via Bluetooth on Mac OS X v10.3.9 and v10.4. They also demonstrated the first Bluetooth PIN and Linkkeys cracker, which is based on the research of Wool and Shaked.


2017

In April 2017, security researchers at Armis discovered multiple exploits in the Bluetooth software in various platforms, including Microsoft Windows,
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, Apple iOS, and Google Android (operating system), Android. These vulnerabilities are collectively called "BlueBorne". The exploits allow an attacker to connect to devices or systems without authentication and can give them "virtually full control over the device". Armis contacted Google, Microsoft, Apple, Samsung and Linux developers allowing them to patch their software before the coordinated announcement of the vulnerabilities on 12 September 2017.


2018

In July 2018, researchers at the Technion – Israel Institute of Technology identified a security vulnerability in the latest Bluetooth pairing procedures: Secure Simple Pairing and LE Secure Connections.


2019

In August 2019, security researchers at the Singapore University of Technology and Design, Helmholtz Center for Information Security, and University of Oxford discovered a vulnerability in the key negotiation that would "brute force the negotiated encryption keys, decrypt the eavesdropped ciphertext, and inject valid encrypted messages (in real-time).".


Health concerns

Bluetooth uses the radio frequency spectrum in the 2.402GHz to 2.480GHz range, which is non-ionizing radiation, of similar bandwidth to the one used by wireless and mobile phones. No specific demonstration of harm has been demonstrated up to date, even if wireless transmission has been included by International Agency for Research on Cancer, IARC in the possible carcinogen list. Maximum power output from a Bluetooth radio is 100Milliwatt#Multiples, mW for class 1, 2.5mW for class 2, and 1mW for class 3 devices. Even the maximum power output of class1 is a lower level than the lowest-powered mobile phones. UMTS and W-CDMA output 250mW, GSM frequency bands, GSM1800/1900 outputs 1000mW, and GSM frequency bands, GSM850/900 outputs 2000mW.


Award programs

The Bluetooth Innovation World Cup, a marketing initiative of the Bluetooth Special Interest Group (SIG), was an international competition that encouraged the development of innovations for applications leveraging Bluetooth technology in sports, fitness and health care products. The competition aimed to stimulate new markets. The Bluetooth Innovation World Cup morphed into the Bluetooth Breakthrough Awards in 2013. Bluetooth SIG subsequently launched the Imagine Blue Award in 2016 at Bluetooth World. The Breakthrough Awards Bluetooth program highlights the most innovative products and applications available today, prototypes coming soon, and student-led projects in the making.


See also

* ANT+ * Bluetooth stack – building blocks that make up the various implementations of the Bluetooth protocol. * Bluetooth profile – features used within the bluetooth stack * Bluesniping * BlueSoleil – proprietary Bluetooth driver. * Bluetooth low energy beacon, Bluetooth Low Energy Beacons (Types of beacons#AltBeacon (Radius Networks), AltBeacon, iBeacon, Eddystone (Google), Eddystone) * Bluetooth Mesh * Continua Health Alliance * DASH7 * Headset (audio) * Hotspot (Wi-Fi) * Java APIs for Bluetooth * Key finder * Li-Fi * List of Bluetooth protocols * List of Bluetooth Profiles * MyriaNed * Near-field communication * RuBee – secure wireless protocol alternative. * Tethering * Thread (network protocol) * Wi-Fi HaLow * ZigBee – low-power lightweight wireless protocol in the ISM band.


Notes


References


External links

*
Specifications
at Bluetooth Special Interest Group, Bluetooth SIG {{Authority control Bluetooth Mobile computers Networking standards Wireless communication systems Telecommunications-related introductions in 1989 Swedish inventions