Bluetooth: How does it work ?

Hello everyone,
This is my first post regarding technology i.e explaining about the bluetooth sharing and it's basics.
we all know that Bluetooth is the main base of sharing any information between two electronic devices, but there is no idea about its specifications standards etc.There by i came infront to explain about this technology as i'm from electronic technology department.

Introduction :-

Bluetooth technology is a high speed low powered wireless technology link that is designed to connect mobiles or any other portable equipment together.

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It is there by connect atmost 8 devices at a time and each device offers a unique 48 bit address from the IEEE standard with connection made point to point.It is a specification IEEE 802.15.1 for the use of low powered radio communications to link electronic device within a short range.Wireless signals transmitted with bluetooth cover short distances typically upto 30 feet.It is achieved by embedded low cost transceivers into the devices.It supports on frequency band of 2.45Ghz and can support upto 721 kbps along with 3 voice channels.

History :-

Bluetooth technology was emerged from the task undertaken by Ericsson mobile communications in 1994 to find an alternative to the use of cables for communication between mobile phones and other electonic devices.In 1998 ,the companies Ericsson,IBM,Nokia & Toshiba joined up there hands and formed the bluetooth special interest group which published the first version in 1999.

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Bluetooth wireless technology was named offer a spanish king,Harald Bluetooth.

Architecture :-

• Core specifications:

Deals with the lower layers of the architecture and describes how the technology works.

• Profile specifications:

Focuses on how to build interoperating devices using the core technology.

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• Bluetooth protocols:

  LMP:Link manager protocol

         -used to handle the setup links
         -for authentication and configuring
  

  L2 CAP:Logical link control and adaptation protocol

         -used for segmentation and reassembly of packets
         -for QoS managment.
  

  HCI: Host controller Interface

          -it allows the information to move from software to hardware.
  

Standards:-

Bluetooth requires physical and protocol standards.

• Physical standard provides the agreement with radio frequency standard.
• Protocol standard aggrement has been made on the time at which the bits are to be sent and the amount of bits that are send and also whether the sent message is same as the recieved message.

working:-

An international agreement has been made for the use of industrial,scientific,medical devices to set aside a frequency band between 2.402 and 2.480Ghz.As bluetooth technology involves the same frequency has been used by many other types of equipment which leads to interference between them.
For avoiding interference,low powered signals are propogated from the device.This is the reason that the range of bluetooth device is restricted to maximum of 10 metres.Even if 8 devices are used in a 10 metre radius,they donot interfere.
The possibility for more than one device to transmit the same frequency at the same time will be avoided by using SPREAD SPECTRUM FREQUENCY HOPPING,by which a device will use alomst a individual randomly choosen frequencies which are desined for a particular range.

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In bluetooth, the spread spectrum frequency flopping method has the frequencies changing almost 1000 time per second.This shows that a lot of devices can use a part of frequency spectrum but no two devices has same frequency,thus interference is avoided.
It is generally explained with an example of one master and 8 slaves.A master is the one who initiates communication with other devices.Master devices govern the communications link and traffic between itself and slave.A slave device is a device which responds to the master.

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The connection and sharing process takes place in four steps.First to create a service by giving description about the service or master mobile.Then to wait for the incoming connection and later by which master will share the data.Last step includes the closing of connection.

References :-

• Frequency Hopping speed spectrum

• wikipedia

• Institute of electrical & electronics Engineers

• Ericsson mobile communication

• Bluetooth