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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