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Bluetooth

From Wikipedia, the free encyclopedia.

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:

• Non-hopping narrowband channel(s) introduced.

  • This channel could be used for advertising bluetooth service profiles offered by various devices to very high volumes of Bluetooth devices simultaneously, since there is no need to do the handshaking with every device. Currently the handshaking process takes approximatelly one second.

  • Unencrypted information such as realtime public transport timetables, basic traffic congestion information and advanced traffic guidance directions can be transmitted to devices passing each other even at high velocities.

• Higher connection speeds

• Multiple speed levels

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

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