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Bluetooth
History
Bluetooth is an Industrial Specification for Wireless
PANs first developed by Ericsson,
later formalized by the Bluetooth
SIG, which was formally announced 20th May 1999.
It was composed by Sony
Ericsson, IBM,
Intel,
Nokia
and Toshiba.
The system is named after a Danish king Harald
Blåtand, otherwise known as Harold
Bluetooth.
Currently
The version shipping currently to consumers
as embedded bluetooth and USB-dongles is 1.1. It is a wireless radio
standard primarily designed for low power consumption, with a a
short-range (from 10 up to 100 meters) and with a low-cost transceiver
microchip
in each device.
It can be used to wirelessly connect periphery
like printers
or keyboards
to computers,
or to have personal
digital assistants (PDAs) communicate with other nearby PDAs
or computers. Cell
phones with integrated Bluetooth technology have also been
released in large numbers, that can connect to computer, PDAs
and, very specially, to handsfree.
However, the standard also includes support for more powerful
longer-range devices suitable for constructing a Wireless
LAN. Every Bluetooth device can simultaneously maintain up
to 7 connections. Every device can be configured to constantly
announce its presence to nearby devices, in order to establish a
connection. It is also possible to password protect a connection
between two devices, so that no others can listen in.
The protocol operates in the license-free ISM
band at 2.45 GHz.
It reaches speeds of 723.1 kbit/s. In order to avoid interfering
with other protocols which may use the 2.45 GHz band, the
Bluetooth protocol divides the band into 79 channels and changes
channels up to 1600 times per second.
Bluetooth should not be compared to WiFi,
a faster protocol requiring more expensive hardware
that covers bigger distances and uses the same frequency range.
While Bluetooth is a cable replacement creating personal area
networking between different devices, wi-fi is a cable
replacement for local area network access. They serve different
purposes.
Future
Bluetooth
The Bluetooth SIG is working on versions 1.2 and 2.0
Bluetooth
1.2
This version is backwards compatible with 1.1 and the major
enhancements include
-
Anonymity
Mode, which masks the hardware address (BD_ADDR) of the
device to protect you from identity snooping and tracking.
Hardware anonymity was already possible starting from 1.1,
but was not implemented, so it was unavailable to normal
consumers.
-
Adaptive
Frequency Hopping (AFH), which improves resistance to
radio interference by avoiding using crowded frequencies in
the hopping sequence
-
Higher
transmission speeds in practice
Bluetooth
2.0
There is no definitive information about what will be included
in 2.0, but some details have been released by Ericsson
research scientists:
Past
Bluetooth
Versions 1.0 and 1.0B had numerous problems and the various
manufacturers had great difficulties in making their products
interoperable. 1.0 and 1.0B also had mandatory
Bluetooth Hardware Device Address (BD_ADDR) transmission in the
handshaking process, rendering anonymity impossible at protocol
level, which was a major set-back for services planned to be
used in Bluetooth environments, such as Consumerium
See
also : Bluechat,
WiFi
External
links
This
content from Wikipedia
is licensed under the GNU
Free Documentation License.
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