BLUETOOTH


Bluetooth is a standard which allows devices to communicate wirelessly (i.e. without any cables). It was designed to enable mobile phones, computers, PDAs, and peripheral devices such as keyboards, mice, headsets all to communicate with each other without a tangle of wires everywhere.

Bluetooth has a major advantage over infrared communications, in that you do not have to point Bluetooth devices directly at each other for them to communicate. They can be anywhere within a certain range (usually 10 metres), and they will be able to communicate with each other.

Bluetooth can also be used to form ad hoc networks of several (up to eight) devices, called piconets. This can be useful for example in a meeting, where all participants have their own Bluetooth-compatible laptops, and want to share files with each other.

Bluetooth


Bluetooth Power Levels


With all the concerns about mobile phone radiation, Bluetooth offers a welcome improvement in safety, given that the power transmitted by Bluetooth devices is 1 thousandth that of a typical mobile phone (1 miliwatt for Bluetooth, as opposed to 1 watt for a typical mobile phone).

There are three classes of Bluetooth devices, with each class referring to the amount of power used by the Bluetooth device. A class 3 Bluetooth device has 1 miliWatt transmission power and a range of 0.1 metres to 10 metres. A class 2 device has 1-2.5 miliWatts transmission power and a range of 10 metres. A class 1 device has transmission power of up to 100 miliWatts and a range of up to 100 metres.

The lower power of Bluetooth devices falling into the class 3 category (e.g. Bluetooth enabled mobile phones and headsets), limits their range to around 10 metres, but then again, this is ample range if one considers a headset or keyboard is rarely separated by more than a few metres from a mobile phone or a computer. Also, the short range also reduces the chance of interference between Bluetooth and other devices.

Bluetooth Frequencies


Bluetooth operates at a frequency range centred at 2.45 GigaHertz, also known as an ISM frequency - a range of frequencies set aside for Industrial, Scientific and Medical devices. This is the same frequency used by wireless networks (known as Wi-Fi or 802.11b)

Bluetooth uses a technique called spread spectrum frequency hopping. This prevents, or at least minimises interference between different devices, by hopping between different frequencies 1600 times per second. This also reduces the liklihood of Bluetooth devices clashing with WiFi devices.

Bluetooth Devices.


Bluetooth is most widely used in mobile phones, where it is superceding infrared as a way of communicating between mobile phones, or between mobile phones and computers. The fact that Bluetooth devices do not have to be pointing directly at each other for communication is a major advantage. Also starting to become more common are Bluetooth headsets for mobile phones. Using a Bluetooth headset means that a mobile phone can stay within a pocket or a bag, and a phone call can be made or received just using the wireless headset.

As Bluetooth use has increased, so the number of devices sporting Bluetooth connections has increased also. Personal Digital Assistants such as Palm and Windows CE devices now tend to include Bluetooth, and Bluetooth enabled printers, keyboard and mice have started to appear.

How do Bluetooth Devices talk to each other?


Bluetooth devices such as mobile phones, headsets and PDAs each have a set of small computer applications called Bluetooth "Profiles". A profile for a headset for instance, would, naturally enough, be called a "headset profile". For a headset to work with a Bluetooth mobile phone, or a computer with Bluetooth, then the phone and the computer would also need a headset profile, to enable them to talk to the headset.

For two Bluetooth devices to talk to each other, they also need to be "paired". The pairing process enables the devices to identify each other, and then communicate with each other, so in the case of a Bluetooth headset and a Bluetooth mobile phone, the headset would identify itself to the mobile phone with the headset server profile, and the mobile phone would reply with the headset client profile, to enable the devices to "pair". Once the devices are then "paired" it is possible to answer phone calls to the mobile phone on the headset just by pressing a button on the headset, and using voice activation (where available), to make phone calls via the headset, whilst the mobile phone is still in a pocket or a bag.

Bluetooth Profiles

Bluetooth Background


The Bluetooth standard was developed by a group called the Bluetooth Special Interest Group (SIG), formed in May 1998. The founding members were Ericsson, Nokia, Intel, IBM and Toshiba. Since then, almost all of the biggest companies in the telecommunications business (e.g. 3Com, Microsoft, Motorola) have joined the Bluetooth SIG and the number of the participating companies is now over 1,500. The version 1.0 of the Bluetooth specification was approved in the summer of 1999, and version 1.0B in December 1999.

See Also:

Bluejacking, Bluesnarfing, Bluesniping, Bluetooth Vulnerabilities

References




www.cyberthinc.com