Bluetooth Technology

Bluetooth technology, developed by Ericsson Mobile Communications, a worldwide telecommunications company based in Sweden, is fast becoming the worldwide standard for short-range wireless communication. The technology was originally developed to easily connect cell phones with peripheral devices such as personal computers. However, other potential applications for home and office quickly emerged.Bluetooth is growing so rapidly that Merrill Lynch predicts that by 2005 there will be more than 2.1 billion Bluetooth compatible devices on the market. 

Bluetooth uses Radio Frequencies to transmit and receive signals in the ISM Band. This is an unlicensed frequency range operating between 2.4 and 2.48 GHz.In order to prevent interference with other devices, Bluetooth employs a spread spectrum frequency hopping technique which takes a narrow band signal and spreads it over a broader portion of the available radio frequency band. This spreading is accomplished by frequency-hopping, a technique developed for encryption that relies on the sender and receiver agreeing on a predefined “hop” sequence for frequency variation. Since only the intended receiver is aware of the transmitter’s hopping pattern, only that receiver can make sense of the data being transmitted. Spread spectrum frequency hopping ensures Bluetooth’s security and limits interference.

The Bluetooth 1.0 specification allows for a gross data transfer rate of 1 Mbps. However, this is a theoretical maximum for half-duplex data transmission. Full duplex transmission is accomplished at 432.6 Kbps. The Bluetooth specification can support three synchronous voice channels at 64 Kbps each. Bluetooth devices typically require 1 mw of power to operate. When two Bluetooth devices establish a connection, they create a network called a piconet. A Bluetooth piconet can contain up to eight Bluetooth devices, with one device serving as a master and up to seven serving as slaves . All devices in a piconet share the same frequency-hopping scheme, which is established when a slave first connects to a master. Bluetooth devices can operate in either a single slave piconet, in which a master connects to only one slave, multi slave piconet, where a master connects to multiple slaves, or in a scatter-net structure. A scatter-net is enabled by masters and slaves with capability to connect to more than one device at a time