Bluetooth

             Bluetooth is a wireless technology which is used in a number of instances to connect and exchange data. It provides a connection between two people with an emphasis on the importance of communication. It is a feature which is used everyday through a number of compatible devices. These include USB, handheld PDA, Phone headset and the most popular, the mobile phone. Through the use of a mobile phone you can send pictures, videos, exchange business cards and also transfer files to your PC. Both data and voice transmissions can be sent and received through the use of short range networks. There are three types of network ranges that are used which depend upon the class of the device/s being used: Class 1, class 3 and the most popular class 2 which uses 2.5mW of power.


                The future for Bluetooth looks very bright and for certain is here to stay. It is a key technology that allows for the mobile information society to work effectively. The once problematic boundaries that restricted users from exchanging information are now not an issue whether it be at home or in the workplace.
                  Bluetooth can be used between several number of devices where one is the master and the others act as slaves, simply receiving information from the main (master) bluetooth device.

Name and logo

      The word Bluetooth is an anglicized version of Old Norse Blátönn or Danish Blåtand, the name of the tenth-century king Harald I of Denmark, who united dissonant Danish tribes into a single kingdom. The implication is that Bluetooth does the same with communications protocols, uniting them into one universal standard.

     The Bluetooth logo is a bind rune merging the Germanic runes  (Hagall) and   (Berkanan).


Implementation

        Bluetooth uses a radio technology called frequency-hopping spread spectrum, which chops up the data being sent and transmits chunks of it on up to 79 frequencies. In its basic mode, the modulation is Gaussian frequency-shift keying (GFSK). It can achieve a gross data rate of 1 Mb/s. Bluetooth provides a way to connect and exchange information between devices such as mobile phones, telephones, laptops, personal computers, printers, Global Positioning System (GPS) receivers, digital cameras, and video game consoles through a secure, globally unlicensed Industrial, Scientific and Medical (ISM) 2.4 GHz short-range radio frequency bandwidth. The Bluetooth specifications are developed and licensed by the Bluetooth Special Interest Group (SIG). The Bluetooth SIG consists of companies in the areas of telecommunication, computing, networking, and consumer electronics.

Uses

         Bluetooth is a standard and communications protocol primarily designed for low power consumption, with a short range (power-class-dependent: 1 meter, 10 meters, 100 meters) based on low-cost transceiver microchips in each device. Bluetooth makes it possible for these devices to communicate with each other when they are in range. Because the devices use a radio (broadcast) communications system, they do not have to be in line of sight of each other.

Introduction to Bluetooth technology

        Bluetooth is a wireless personal area network technology (WPAN for short), a low-range wireless network technology used for linking devices to one another without a hard-wired connection. Unlike the IrDa technology (which uses an infrared connection), Bluetooth devices do not need a direct line of sight to communicate, which makes them more flexible in use and allows room-to-room communication in small spaces.

        The aim of Bluetooth is to transmit voice or data between devices with low-cost radio circuits, over a range of about ten to just under a hundred metres, using very little power.

        Bluetooth technology is designed mainly for linking devices (such as printers, mobile phones, home appliances, wireless headsets, mouses, keyboards, etc.), computers, or PDAs to one another, without using a wired connection. Bluetooth is also becoming more and more commonly used in mobile phones, allowing them to communicate with computers or PDAs, and is especially widespread in hands-free accessories like Bluetooth headsets. Bluetooth headsets act as advanced earpieces which include remote control features.

        Bluetooth technology was originally developed by Ericsson in 1994. In February 1998, a group called the Bluetooth Special Interest Group (Bluetooth SIG), with over 2000 companies including Agere, Ericsson, IBM, Intel, Microsoft, Motorola, Nokia and Toshiba, was formed in order to produce the specifications for Bluetooth 1.0, which were published in July 1999.

The name "Bluetooth" comes from the Danish king Harald I (910-986), nicknamed Harald I Blåtand ("the blue-toothed"), who is credited with uniting Sweden and Norway, as well as introducing Christianity to Scandinavia.

Characteristics

       Bluetooth can reach transfer speeds of about 1 Mbps, which corresponds to 1600 hops per second in full-duplex mode, with a range of roughly ten metres when using a class II transmitter, and a little under a hundred metres using a class I transmitter.

   The Bluetooth standard actually defines 3 classes of transmitters, whose range varies as a function of their radiating power:
Class Power (signal loss) Range
I  100 mW (20 dBm) 100 metres
II  2.5 mW (4 dBm) 15-20 metres
III  1 mW (0 dBm) 10 metres

  Unlike IrDA, the primary competing technology, which uses light radiation to send data, Bluetooth uses radio waves (in the 2.4 GHz frequency band) to communicate, and as a result, Bluetooth devices don't have to be in visual communication to exchange data. This means that two devices can communicate even if they are on either side of a wall, and best of all, Bluetooth devices can detect one another without the user's involvement, so long as they are within each other's range.

Bluetooth norms

         The Bluetooth standard is broken down into multiple norms:

• IEEE 802.15.1 defines Bluetooth 1.x, which can reach speeds of 1 Mbps;

• IEEE 802.15.2 recommends practices for using the 2.4 GHz frequency band (the frequency also used by WiFi). However, this standard has not yet been approved;

• IEEE 802.15.3 is a standard currently being developed, which would offer broadband speed (20 Mbps) with Bluetooth;

• IEEE 802.15.4 is a standard currently being developed for use with low-speed Bluetooth applications.