Bluetooth Basics
Bluetooth wireless technology is a short-range communications technology intended to replace the cables connecting portable and/or fixed devices while maintaining high levels of security. The key features of Bluetooth technology are robustness, low power, and low cost. The Bluetooth specification defines a uniform structure for a wide range of devices to connect and communicate with each other.
Bluetooth technology has achieved global acceptance such that any Bluetooth enabled device, almost everywhere in the world, can connect to other Bluetooth enabled devices in proximity. Bluetooth enabled electronic devices connect and communicate wirelessly through short-range, ad hoc networks known as piconets. Each device can simultaneously communicate with up to seven other devices within a single piconet. Each device can also belong to several piconets simultaneously. Piconets are established dynamically and automatically as Bluetooth enabled devices enter and leave radio proximity.
A fundamental Bluetooth wireless technology strength is the ability to simultaneously handle both data and voice transmissions. This enables users to enjoy variety of innovative solutions such as a hands-free headset for voice calls, printing and fax capabilities, and synchronizing PDA, laptop, and mobile phone applications to name a few.
Core Specification Versions
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Version 2.0 + Enhanced Data Rate (EDR), adopted November, 2004
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Version 1.2, adopted November, 2003
Specification Make-Up
Unlike many other wireless standards, the Bluetooth
wireless specification gives product developers both link layer and
application layer definitions, which supports data and voice
applications.
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
technologi
es
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.
Range
The operating range depends on the device class:
-
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 30 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. 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