Sunday, 15 September 2013

Bluetooth Technical Operations




Bluetooth is a high speed, low powered wireless link



technology that's designed to connect phones or other



portable equipment together with little to no work



required by the user. Unlike infrared, Bluetooth



doesn't require line of site positioning to work.





Current prototype circuits are contained on a board



that is 0.9 cm square, with a much smaller circuit



board being developed.





When one Bluetooth device comes in contact with



another, they will automatically exchange addresses



and details of capability. Then, they can establish



a 1 MB link with security that they will use as



required. The protocols involved with handle both



data and voice, with a very flexible topography.





The technology achieves its goal by embedding tiny,



non expensive short range tranceivers into the



devices available today. The radio operates on the



2.45 GHz frequency band, and supports up to 721



KBps, along with three voice channels.





Each devices offers a unique 48 bit address from



the IEEE 802 standard, with the connections being



point to point or multipoint. The max range is



10 meters, although it can be extended to 100



meters by increasing the power. The devices are



also protected from radio interference by changing



their frequencies, also known as frequency hopping.





What's important, is the fact that Bluetooth



devices won't drain battery life. The specification



targets power consumption of the device, limiting



the drain on the battery. The radio chip will



consume only 0.3mA in stand by mode, which is less



than 5% of the power that standard phones use.





Bluetooth will also guarantee security at the bit



level. The authentification is controlled by the



user via a 128 bit key. The radio signals can



be coded with anything up to 128 bit. With the



frequency hopping, Bluetooth is already very



hard to listen into.





The baseband protocol is a combination of both



circuit and packet switches. Slots can be reserved



for synchronous packets as well. Each packet



will be transmitted in a different hop frequency.



Normally, a packet covers a single slot although



it can be extended to cover up to five slots.





Bluetooth can also support data channels of up to



three simultaneous voice channels. Therefore,



it's possible to transfer the data while you talk



at the same time. Each individual voice channel



will support 64 KB.





From a technical standpoint, Bluetooth is very



different indeed. It's the best wireless method



in the world, surpassing even infrared. For



communication on the go, Bluetooth is indeed



very hard to compete with.

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