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Topic this month:

Bluetooth

October/November 2009

Bluetooth as you might suspect, has nothing to do with dentures, but a lot with wireless communication. The name originates from a Danish King who ruled in the tenth century and united Danish tribes (see Wikipedia). As with the old Danish King Bluetooth tries to unite wireless protocols into one.

Bluetooth is a short distance radio protocol that can establish a Personal Area Network (PAN) which in turn connects fixed or mobile devices together. It is similar to connecting your computer to a Local Area Network (LAN), only it is wireless.


Photo courtesy Wikipedia

A master Bluetooth device can connect up to seven other devices. An eight device network is called a piconet. A further 255 inactive devices can also be on the same net and the master will deactivate and reactivate devices as required.

Its main purpose was to replace RS232 serial connections and cables, and later also replaced the less popular infrared interfaces seen mostly on laptops and mobile phones

Technically it employs spread spectrum by frequency-hopping using 79 different frequencies. Three different classes of Bluetooth devices exist that stipulate its transmission range: Class I approximately 100m, class II 10m and class III with a range of approximately 1m.

Bluetooth devices can employ PIN nrs or key pairs to encode the air interface to achieve privacy and a secure connection between two devices. The process of exchanging keys is called paring and once the two devices are locked to each other they are said to be bonded.

Bluetooth is similar to WiFi in the sense that it aims to remove wires and cables. Where WiFi is mainly aimed at converting the LAN to wireless at a fixed location, Bluetooth is more aimed at public places where mobility is high and devices are open to public connections. Sometimes Bluetooth is referred to as the 'shortwire' solutions, your connection between your mobile device and the nearest LAN point. WiFi is referred to as the 'longwire' solution providing connections between LAN hubs routers and PCs.

In an environment where both WiFi and Bluetooth operate, Bluetooth will loose some of its bandwidth and decline between 17and 22% of data.

Bluetooth is an inexpensive technology that uses an universally accepted protocol to connect devices automatically over short distances, has low energy consumption and it seems to be here to stay.

See the following links:

Bluetooth.com
Bluetooth SIG Membership
How it works
Wikipedia
Tutorial

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