What is Bluetooth

Bluetooth

 

Bluetooth is a technology staff without son Network (noted WPAN for Wireless Personal Area Network ), that is to say, network technology without son of a low range for connecting devices together wirelessly link. Unlike IrDa technology (infrared link), Bluetooth devices do not require a direct line of sight to communicate, which makes it more flexible to use and allows for communication from one room to another, in small spaces. . 

 

Goal

The purpose of Bluetooth is to transmit data or voice between equipment with a low-cost radio circuit, on a radius of about ten meters to a little less than a hundred meters and with low power consumption.

Thus, Bluetooth technology is mainly intended to connect peripherals (printers, mobile phones, home appliances, wireless headsets, mice, keyboard, etc.), computers or PDAs, without using a link. wired. Bluetooth technology is also increasingly used in mobile phones, to enable them to communicate with computers or PDAs and especially with hands-free devices such as bluetooth headsets. Bluetooth headsets can be used as an advanced audio headset with built-in remote control capabilities. 

Bluetooth technology was originally developed by Ericsson in 1994. In February 1998 an interest group called Bluetooth Special Interest Group ( Bluetooth SIG ), bringing together more than 2000 companies including Agere, Ericsson, IBM, Intel, Microsoft, Motorola, Nokia and Toshiba, were formed to produce the Bluetooth 1.0 specifications, which were released in July 1999.

The name "Bluetooth" (literally "blue tooth") refers to the name of the Danish king Harald II (910-986), nicknamed Harald II Blåtand ("blue tooth"), who is credited with the unification of Sweden and Norway and the introduction of Christianity in the Scandinavian countries. 

Characteristics

Bluetooth provides speeds of the order of 1 Mbps, corresponding to 1600 exchanges per second in full-duplex, with a range of about ten meters with a class II transmitter and a little less a hundred meters with a class I transmitter. 

The Bluetooth standard indeed defines 3 classes of transmitters offering different ranges according to their transmission power: 

Class	Power (weakening)	Scope
I	100 mW (20 dBm)	100 meters
II	2.5 mW (4 dBm)	15-20 meters
III	1 mW (0 dBm)	10 meters

Unlike IrDA technology, the main competing technology using light rays for data transmission, Bluetooth technology uses radio waves (2.4 GHz frequency band) to communicate, so devices do not have to be visually linked. to communicate. Thus two devices can communicate by being located on both sides of a partition and, icing on the cake, Bluetooth devices are able to detect without intervention from the user if they are within range one of the other. 

Bluetooth standards

The Bluetooth standard is broken down into different standards:

• IEEE 802.15.1 defines the Bluetooth 1.x standard to achieve a rate of 1 Mbit / sec;
• IEEE 802.15.2 offers recommendations for using the 2.4 GHz frequency band (frequency also used by WiFi). This standard is not yet validated;
• IEEE 802.15.3 is a standard under development to offer broadband (20 Mbit / s) with Bluetooth technology;
• IEEE 802.15.4 is a standard under development for low speed Bluetooth applications.