BlueTooth

What is Bluetooth?

Bluetooth is a wireless technology for communication ove short distances. It uses low power radio frequencies to exchange data between the devices. Blutooth is normally used to connect deices such as printer, mobile, Laptops within a room. THis type of network is called PAN (Personal Area Network).

 The Range of Bluetooth is about 10 - 15 Metres. It works on the principle of Master and Slaves. Where One device acts as a master and other devices are slaves. Slaves always follows the master. Each master can have upto 7 active Slaves.

 Thus there are two types of network 

1. Piconet
2. Scatternet.

Piconet :

Here the master controls the overall networks. It uses Time Division Multiplexing. The master controls the global clock. The figure shows the piconet.

 

Scatternet :

It is a collection of piconets or we can say that many piconets when linked together forms a scatternet. The figure shows the scatternet. Here Master of one piconet can be a slave of other piconet and vica versa. 

 

Applications of Blutooth :

• Can be used in  communication between a mobile and a headset.
• In communication between a cell phone and a Bluetooth compatible car stereo system
• Wireless headset and Intercom.
• Wireless networking between PCs in a confined space and where little bandwidth is required.
• Wireless communication with PC input and output devices. Commonly mouse, keyboard and printer.
• Transfer of files, contact details, calendar appointments, and reminders between devices.
• For controls where infrared was often used.
• For low bandwidth applications.
• Sending small advertisements from Bluetooth-enabled advertising hoardings to other.
• Wireless bridge between two Industrial Ethernet.
• Dial-up internet access on personal computers or PDAs using a data-capable mobile phone as a wireless modem.
• Real-time location systems (RTLS), are used to track and identify the location of objects in real-time using “Nodes” or “tags” attached to, or embedded in the objects tracked, and “Readers” that receive and process the wireless signals from these tags to determine their locations^.
• Personal security application on mobile phones for prevention of theft or loss of items. The protected item has a Bluetooth marker (e.g. a tag) that is in constant communication with the phone. If the connection is broken (the marker is out of range of the phone) then an alarm is raised. This can also be used as a man overboard alarm. A product using this technology has been available since 2009.

Working of Bluetooth : 

During the pairing process, the two devices involved establish a relationship by creating a secret code known as a link key. If a link key is stored by both devices they are said to be paired or bonded. A device that wants to communicate only with a bonded device can authenticate the identity of the other device, and so be sure that it is the same device it previously paired with. Once a link key has been generated, an authenticated ACL link between the devices may be ciphered so that the data that they exchange over the airwaves is protected against unauthorized access.