Bluetooth, also known as IEEE 802.15.1, refers to short-range communications technology for wireless personal area networks (PAN). The specification was developed in 1994 by Sven Mattisson and Jaap Haartsen, both employed by Ericsson Mobile Platforms in Sweden. It was formalized by the Bluetooth Special Interest Group (Bluetooth SIG), a consortium formed in May 1998 by the companies Nokia, Ericsson, IBM and Intel, though as of 2007 the SIG has more than 9,000 member companies internationally.
The group’s main objective in developing Bluetooth was to replace the cables that connect devices such as laptops, PCs, mobile phones, printers and digital cameras while maintaining high levels of security, enabling these devices to exchange information without cables. Bluetooth also features low power consumption and low cost.
Through Bluetooth technology, devices are able to simultaneously handle both data and voice transmissions, allowing for numerous solutions including hands-free headsets for voice calls, printing and fax capabilities, and synchronizing PDA, laptop and mobile phone applications.
Bluetooth technology derives its name from the historical King Harald "Bluetooth" Gormson I of Denmark and Norway, who was known for unifying tribes of Denmark and Norway that were previously at odds with each other. This is analogous with Bluetooth’s objective of unifying different technologies such as mobile phones, computers and other devices. The Bluetooth logo is a bind rune, formed by two Nordic runes: hagall ("H" in modern Latin) and bjarkan ("B" in modern Latin), intended to stand for "Harald" and "Bluetooth," respectively.
Bluetooth-enabled devices must be within short distance of each other in order to communicate. Since each device may simultaneously communicate with up to seven other devices, a number of them may form a short-range ad hoc network known as a "piconet." They use a radio communications system so that they may not necessarily be in line of sight of each other, and if the received transmission is powerful enough, they may even be in separate rooms.
There are three radio classes for the low-cost transceiver microchips in each Bluetooth-enabled device which determine the operating range for the device. Class 1 radios have a maximum permitted power of 100 mW per 20 dBm, for a range of 100 meters. Class 2 radios have a maximum permitted power of 2.5 mW per 4 dBm, for a range of 10 meters. Class 3 radios have a maximum permitted power of 1 mW per 0 dBm, for a range of 1 meter.
There have been several revisions for the Bluetooth specification. As of 2007, it has undergone Bluetooth 1.0 and 1.0B; 1.1 and 1.2 which addressed errors in the original specification and featured new enhancements such as Received Signal Strength Indicator (RSSI), adaptive frequency-hopping spread spectrum (AFH), and Extended Synchronous Connections (eSCO); 2.0 with Enhanced Data Rate (EDR); and 2.1 with EDR, which featured sniff subrating, Encryption Pause Resume and Quality of Service (QoS) improvements. Bluetooth 3.0, which plans to adopt ultra-wideband (UWB) radio technology in order to achieve data rates of up to 480 Mbps, is currently in development.
Operating systems that support Bluetooth include Mac OS X version 10.2 and higher, Windows XP Service Pack 2 and higher, and Linux.