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Bluetooth - technical definition

A specification to standardize wireless transmission and synchronize data among a wide variety of devices such as PCs, cordless telephones, headsets, printers, and PDAs.The initial effort (April, 1998) was in the form of a consortium of Intel, Microsoft, IBM,Toshiba, Nokia, Ericsson, and Puma Technology and was code-named Bluetooth after Harald Blaatand, the tenth-century Danish king who brought warring tribes together and unified Denmark. Bluetooth is now formalized in IEEE 802.15.1 (2002) as the specification for a wireless personal area network (WPAN) operating in the 2.45 GHz range of the ISM frequency band. Bluetooth employs frequency-hopping spread spectrum (FHSS), with devices stepping through a carefully choreographed pseudorandom hop sequence that makes data collisions highly unlikely even though large numbers of transmissions share the same frequency band. Devices hop through a set of 79 (United States and Europe) or 23 (Spain, France, and Japan) channels spaced 1 MHz apart at a rate of about 1600 hops per second, with each hop lasting 62.5

See Bluetooth in Computer

A wireless personal area network (WPAN) for short-range transmission of digital voice and data. Using omnidirectional radio waves, Bluetooth transmits through walls and other non-metal barriers. Although the term is practically synonymous with cellphone headsets and in-vehicle, hands-free telephony, Bluetooth is also used in many other applications, including wireless keyboards, mice and game controllers. See WPAN.

The name comes from ancient King Harald Blatan (Bluetooth in English) of Denmark. Ericsson, a Scandinavian company, first developed the specification and was a co-founder in 1998 of the Bluetooth Special Interest Group (www.bluetooth.com), which governs the specification. Bluetooth is also standardized as an IEEE wireless personal area network (see 802.15). See Bluetooth glossary.

Bluetooth Specifications
Bluetooth transmits in the same unlicensed 2.4 GHz band as Wi-Fi, but with a different transmission method. It uses frequency hopping spread spectrum (FHSS), which changes its signal randomly to one of 79 channels 1,600 times per second. If there is interference from other devices, transmission continues, but speed is downgraded. However, Bluetooth 2.0 + EDR (Enhanced Data Rate) avoids channels that are interfering with other wireless devices. Future versions of Bluetooth are expected to use UWB transmission (see WiMedia Alliance). See spread spectrum.

Supporting point-to-point and multipoint (see piconet), following are Bluetooth's data rates and power ratings:


            Data              Maximum    Approx.
            Rate               Power     Range
  Version  (Mbps)       Class   (mW)    (meters)

   1.2        1           1     100       100
   2.0+EDR    3           2       2.5      10
                          3       1         1

Wibree - Ultra Low Power (ULP) Bluetooth
In 2007, Nokia's Wibree technology was added to the Bluetooth specification and renamed ULP Bluetooth. Using up to a quarter of the power of Bluetooth at 1 Mbps, Wibree enables sensors, wristwatches and toys with tiny batteries to employ wireless. To use Bluetooth and Wibree at the same time, a dual-mode device is required.

Two Wireless Systems

All Bluetooth cellphone users are employing two wireless technologies: Bluetooth between ear and cellphone and the carrier's transmission technology between cellphone and cell tower (see GSM and CDMA).

Game Controllers

This "gamepad" from Sony uses Bluetooth to communicate with the PlayStation3 game console. See video game controller. (Image courtesy of Sony Corporation.)