Bluetooth
Bluetooth is a wireless LAN technology designed to connect devices of different functions such as telephones, notebook, computers, cameras, printers, coffee makers, and so on. A Bluetooth LAN is an ad hoc network, which means that the network is formed spontaneously; the devices sometimes called gadgets find each other and make a network called piconet. A Bluetooth LAN can even be connected to the Internet if one of the gadgets has this capability. A Bluetooth LAN, by nature, cannot be large.
Bluetooth technology has several applications. Peripheral devices of computer can communicate with the computer through this technology (wireless mouse or keyboard). Monitoring devices can communicate with sensor devices in a small health care center. Home security devices can use this technology to connect different sensors to the main security controller. Conference attendances can synchronize their palmtop computers at a conference.
Bluetooth was originally started as a project by the Ericsson Company. It is named for Harald Blaatand, the king of Denmark (940-981) who united Denmark and Norway. Blaatand translates to Bluetooth in English.
Architecture
Bluetooth defines two types of networks:
A Bluetooth network is called piconet, or a small net. A piconet can have up to eight stations, one of which is called the master; the rest is called slaves. All the slave stations synchronize their clock and hopping sequence with the master slave. Note that a piconet can have only one master station. The communication between the master and the slaves can be one-to-one or one-to-many. Figure shows a piconet.
Although a piconet can have a maximum of seven slaves, an additional eight slaves can be in the parked state. A slave in a parked state is synchronized with the master, but cannot take part in communication until it is moved from the parked state. Because only eight stations can be active in a piconet, activating a station from the parked state means that an active station must go to the parked state.
Scatternet
Piconet can be combined to form what is called a scatternet. A slave station in one piconet can become the master in another piconet. This station can receive messages from the master in the first piconet (as a slave) and, acting as a master deliver it to slaves in the second piconet. A station can be a member of two piconets. Figure shown below illustrates a scatternet.
Bluetooth Devices
A Bluetooth device has a built-in short range radio transmitter. The current data rate is 1 Mbps with a 2.4-GHz bandwidth. This means that there is a possibility of interference between IEEE 802.11b wireless LANs and Bluetooth LANs.