CertiGuide to A+ (A+ 4 Real)  9  Chapter 13: Basic Networking Terminology       9  OSI Reference Model and Networking Protocols and Technologies            9  Layer 2 - Data Link Layer

PAN 1 FireWire

Ericsson, IBM, Intel, Nokia, and Toshiba created this technology of wireless communication in 1998 The basic purpose of the Bluetooth is maintenance of an economic radio communication between various types of electronic devices while considerable importance is given to compactness of the electronic components.

The Bluetooth interface allows the transfer of voice with a speed of 64 Kbps. Data is transferred asymmetrically with 721 Kbps in one direction and 57.6 Kbps in another, and symmetrically at 432.6 Kbps. The transceiver, which has a frequency of 2.4 GHz, allows, depending on the degree of capacity, the establishment of communication within a limit of 10 to 100 meters.

Bluetooth works by the FHSS ¹⁸⁸ (Frequency-Hopping Spread Spectrum) principle. The brief explanation is that the transmitter breaks the communication into packets and transfers them with a reorganization of frequency (1600 times per one second), or a sample made from 79 sub-frequencies. To “understand" each other, the devices can only be adjusted on the same sample of transfer; for outside devices, the transferred information will be like usual transmission noise.

The basic element of a Bluetooth network is so-called piconet¹⁸⁹- the set of 2 up to 8 devices working on the same sample. In every piconet, one device works as the master and the others as slaves. The master defines a sample on which all slave devices of a given piconet will work and synchronize their work. The Bluetooth standard provides an independent and unsynchronized connection among its own piconets (up to 10) in a scatternet¹⁹⁰. For this purpose, each pair of piconets should have, as a minimum, one common device that will be master in one and slave in another. Thus, within the limits of a separate scatternet within the Bluetooth interface, a maximum of 71 devices can simultaneously be connected. However, nobody limits the application of devices or gates using the Internet for more distant communications.

The most common use of Bluetooth is the creation of Personal Area Networks (PAN¹⁹¹), including various devices such as, mobile telephones, PDAs¹⁹², MP3¹⁹³ players, computers, microwave ovens, refrigerators, etc. The ability of voice transfer allows the inclusion of the Bluetooth interface in cellular telephones.

The Bluetooth technology can make a revolution in the world of the personal communications.¹⁹⁴

PAN 1 FireWire