Bluetooth

Bluetooth is an industrial specification for wireless personal area networks (PANs). Bluetooth provides a way to connect and exchange information between devices such as mobile phones, laptops, PCs, printers, digital cameras, and video game consoles over a secure, globally unlicensed short-range radio frequency. The Bluetooth specifications are developed and licensed by the Bluetooth Special Interest Group.

Why is it called Bluetooth?

Harald Bluetooth was king of Denmark in the late 900s. He managed to unite Denmark and part of Norway into a single kingdom then introduced Christianity into Denmark. He left a large monument, the Jelling rune stone, in memory of his parents. He was killed in 986 during a battle with his son, Svend Forkbeard. Choosing this name for the standard indicates how important companies from the Nordic region (nations including Denmark, Sweden, Norway and Finland) are to the communications industry, even if it says little about the way the technology works.

Bluetooth is a standard and communications protocol primarily designed for low power consumption, with a short range (power-class-dependent: 1 meter, 10 meters, 100 meters) based on low-cost transceiver microchips in each device.

List of applications

More prevalent applications of Bluetooth include:

* Wireless control of and communication between a mobile phone and a hands-free headsetor car kit. This was one of the earliest applications to become popular.

* Wireless networking between PCs in a confined space and where little bandwidth is required.

* Wireless communications with PC input and output devices, the most common being the mouse, keyboard and printer.

* Transfer of files between devices with OBEX.

* Transfer of contact details, calendar appointments, and reminders between devices with OBEX.

* Replacement of traditional wired serial communications in test equipment, GPS receivers,
medical equipment, bar code scanners, and traffic control devices.

* For controls where infrared was traditionally used.

* Sending small advertisements from Bluetooth enabled advertising hoardings to other,discoverable, Bluetooth devices.

* Seventh-generation game consoles—Nintendo Wii, Sony PlayStation 3—use Bluetooth for their respective wireless controllers.

* Dial-up internet access on personal computer or PDA using a data-capable mobile phone as a modem.

* Receiving commercial advertisements ("spam") via a kiosk, e.g. at a movie theatre or lobby

Spectrum

Bluetooth technology operates in the unlicensed industrial, scientific and medical (ISM) band at 2.4 to 2.485 GHz, using a spread spectrum, frequency hopping, full-duplex signal at a nominal rate of 1600 hops/sec. The 2.4 GHz ISM band is available and unlicensed in most countries.

Interference

Bluetooth technology’s adaptive frequency hopping (AFH) capability was designed to reduce interference between wireless technologies sharing the 2.4 GHz spectrum. AFH works within the spectrum to take advantage of the available frequency. This is done by detecting other devices in the spectrum and avoiding the frequencies they are using. This adaptive hopping allows for more efficient transmission within the spectrum, providing users with greater performance even if using other technologies along with Bluetooth technology. The signal hops among 79 frequencies at 1 MHz intervals to give a high degree of interference immunity.

Power

The most commonly used radio is Class 2 and uses 2.5 mW of power. Bluetooth technology is designed to have very low power consumption. This is reinforced in the specification by allowing radios to be powered down when inactive.

Data Rate

1 Mbps for Version 1.2; Up to 3 Mbps supported for Version 2.0 + EDR

Being an IEEE standard will be a big plus to widespread adoption of Bluetooth, and IEEE 802.15 working group for personal area networks (PAN) announced that they will be adopting Bluetooth as the IEEE 802.15 standard.