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Bluetooth
Bluetooth is used to connect and exchange information between digital devices
like personal digital assistant (PDA), mobile phones, laptops, computers,
printers, digital cameras via a secure and low-cost globally available short
range radio-frequency. Bluetooth is used in wireless personal area network
(PAN). Bluetooth connection and information exchange can only occur if the two
devices can be brought in range to each other.
A Bluetooth device can have two roles while communication takes place, master
and slave. A Bluetooth device playing the role of master can communicate up to
seven devices playing the role of slave. At any time, data can be transferred
from master device to one slave at a time. Communicating with multiple slave
devices, a master device switches from slave to slave in a technique called
round-robin. This group of eight devices in communication is then called as
piconets. The Bluetooth specification also permits connectivity between two or
more piconets referred to as scatternet. In scatternet, some devices perform as
bridge between piconets by playing a role of master in one piconet and a role of
slave in another piconet simultaneously. However, scatternet devices are
not available in the market yet.
Pairs of devices may establish a trusted relationship by learning (by user
input) a shared secret known as a passkey. A device that wants to communicate
only with a trusted device can cryptographically authenticate the identity of
the other device. Trusted devices may also encrypt the data that they exchange
over the air so that no one can listen in.
A bluetooth device must interpret certain possible applications called
profiles. Profiles defined by Bluetooth SIG are: Advanced Audio Distribution
Profile (A2DP), Audio/Video Remote Control Profile (AVRCP), Basic Imaging
Profile (BIP), Basic Printing Profile (BPP), Common ISDN Access Profile (CIP),
Cordless Telephony Profile (CTP), Dial-up Networking Profile (DUN), Fax Profile
(FAX), File Transfer Profile (FTP), General Audio/Video Distribution Profile (GAVDP),
Generic Access Profile (GAP), Generic Object Exchange Profile (GOEP), Hands Free
Profile (HFP), Hard Copy Cable Replacement Profile (HCRP), Headset Profile (HSP),
Human Interface Device Profile (HID), Intercom Profile (ICP), Object Push
Profile (OPP), Personal Area Networking Profile (PAN), Serial Port Profile (SPP),
Service Discovery Application Profile (SDAP), SIM Access Profile (SAP),
Synchronisation Profile (SYNCH) and Video Distribution Profile (VDP).
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