# Bluetooth Technology

Bluetooth® wireless technology[1] is a short-range communications technology intended to replace the cables connecting portable and/or fixed devices while maintaining high levels of security.

The global acceptance of Bluetooth and the structure of Bluetooth technology allows any Bluetooth-enabled device to connect to any other Bluetooth-enabled device located within a specified proximity.

All the information within this section and more detailed technology description are available on www.bluetooth.com web site.

Connections between Bluetooth-enabled electronic devices allow these devices to communicate wirelessly through short-range, ad hoc networks known as piconets. Piconets are established dynamically and automatically as Bluetooth-enabled devices enter and leave radio proximity. Each device in a piconet can simultaneously communicate with up to seven other devices within that single piconet and each device can also belong to several piconets simultaneously. The ways in which you can connect your Bluetooth devices are almost limitless.

The range of Bluetooth technology is application-specific. The Core Specification mandates a minimum range of 10 meters or 30 feet, but there is no set limit and manufacturers can tune their implementations to provide the range needed to support the use cases for their solutions.

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 the technology detecting other devices in the spectrum and avoiding the frequencies they are using. This adaptive hopping among 79 frequencies at 1 MHz intervals gives a high degree of interference immunity and also allows for more efficient transmission within the spectrum. For users of Bluetooth technology frequency hopping provides greater performance even if other technologies are being used along with Bluetooth technology.

Range

Range may vary depending on class of radio used in an implementation:

- Class 3 radios – have a range of up to 1 meter or 3 feet
- Class 2 radios – most commonly found in mobile devices – have a range of 10 meters or 33 feet
- Class 1 radios – used primarily in industrial use cases – have a range of 100 meters or 300 feet

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 including allowing radios to be powered down when inactive.

The Generic Alternate MAC/PHY in Version 3.0 HS enables the discovery of remote AMPs for high speed devices and turns on the radio only when needed for data transfer giving a power optimization benefit as well as aiding in the security of the radios.

Data Rate

- 1 Mbps for Version 1.2;
- Up to 3 Mbps supported for Version 2.0 EDR
- Up to 24 Mbps supported for Version 3.0 HS