Understanding Bluetooth
by: Jon Arnold
Bluetooth technology is a low-power, low-cost wireless
technology for short-range radio communication between various
fixed and/or portable electronic devices such as mobile phones,
laptops, PDAs, cars, stereo headsets, MP3s, digital cameras, PCs
and computer peripherals. Bluetooth also refers to the standard
communication protocol (IEEE 802.15.1) specifically designed for
this kind of short-range wireless communication.
The core of Bluetooth technology lies in a low-cost 9 mm x 9 mm
microchip that functions as a short-range radio link when
inserted into an electronic device, making the device
Bluetooth-enabled. Wireless communication between various
bluetooth-enabled devices takes place via these radio links,
instead of via cables as used in normal networking. Since
Bluetooth technology uses radio signals, which are
omni-directional and can be transmitted through walls and other
obstacles, Bluetooth-enabled devices don’t need to be in line of
sight or be pointing at each other.
Bluetooth radio modules operate in the open, unlicensed ISM
(industrial–scientific–medical) spread-spectrum 2.4 GHz
frequency band, divided into 79 channels separated by 1 MHz
each. To avoid interference from other signals, the Bluetooth
signal hops to a new channel every time it transmits or receives
a data packet, making Bluetooth connection robust and secure.
The communication range of Bluetooth technology varies from 1 m
to 100 m, depending upon the maximum power permitted (1 mW to
100 mW). Because of this channel hopping, there should not be a
consistent problem with other devices using the 2.4 Ghz
frequency band, such as old cordless phones.
Each Bluetooth-enabled device can simultaneously communicate
with up to seven other devices within a single personal area
network, called a piconet. Each device can simultaneously belong
to several piconets. Each device negotiates with each other via
a defined device name so that each device can keep track of who
it is communicating with. The device name to use when you are
setting up your Bluetooth device is typically cleared stated in
the accompanying device documentation.
Bluetooth technology offers built-in security with 128-bit
encryption and PIN code authentication. When Bluetooth products
identify themselves, they use the PIN code the first time they
connect, thereafter staying securely connected.
Practical Applications of Bluetooth
Networking
Some of the popular applications of Bluetooth technology are in
wireless networking between a mobile phone and a laptop/desktop,
between a mobile phone and a hands-free headset, between PCs in
a restricted space and between the input and output devices of a
PC (e.g., mouse, keyboard, printer). Bluetooth technology can
also be used to transfer files, images and MP3 files between
mobile phones or between MP3 players/digital cameras and
computers.
Limitations of Bluetooth Technology
Short communication range (up to 100 m) is the greatest
limitation of Bluetooth technology. Also, the data transfer
rates are much lower compared to other wireless communication
technologies. Susceptibility to interference from other devices
operating in the 2.4 MHz band, notwithstanding adaptive
frequency hopping, is another limitation. The Bluetooth
technology is still not fully developed, so there is plenty of
room for improvement.
Bluetooth-Enabled Devices
The Bluetooth wireless technology specification is available
free-of-charge to Bluetooth member companies around the world.
Many companies are interested in making their devices
Bluetooth-enabled in order to avoid the clutter of wires with
seamless connections and offer simultaneous transmission of data
and voice as in hands-free talking.
Bluetooth technology is commercially available in a wide range
of applications such as mobile phones,
automobiles, medical devices, play stations and many more.
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