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Bluetooth

Bluetooth is the technology using short range radio links, intended to replace the cables connecting portable/fixed electronic devices. Using this technology, users can have all mobile and fixed computer devices be totally coordinated. The standard defines a uniform structure for a wide range of devices to communicate with each other, with minimal user effort. Its key features are robustness, low complexity, low power and low cost. The technology also offers wireless access to LANs, PSTN, the mobile phone network and the Internet for a host of home appliances and portable handheld interfaces. 

Bluetooth is a short-distance wireless technology with the following technical characteristics:

  • license-free 2.4 GHz frequency band

  • 400 kbps of data symmetrically or 700 to 150 kbps of data asymmetrically

  • Range approximately 10 m at 1 mW transmitting power, approximately 100 m (in the open) at 100 mW

Bluetooth supports two kinds of links : Asynchronous Connectionless (ACL) links for data transmission and Synchronous Connection oriented (SCO) links for audio/voice transmission. The gross Bluetooth data rate is 1 Mbps while the maximum effective rate on an asymmetric ACL link is 721 Kbps in either direction and 57.6 Kbps in the return direction. A symmetric ACL link allows data rates of 432.6 Kbps. Bluetooth also supports up to three 64Kbps SCO channels per device. These channels are guaranteed bandwidth for transmission.

The Bluetooth core system consists of an RF transceiver, baseband, and protocol stack. The system offers services that enable the connection of devices and the exchange of a variety of data classes between these devices. During typical bluetooth operation, a physical radio channel is shared by a group of devices that are synchronized to a common clock and frequency hopping pattern. One device provides the synchronization reference and is known as the master. All other devices are known as slaves. A group of devices synchronized in this fashion form a piconet. This is the fundamental form of communication for Bluetooth wireless technology.

The transmission range of Bluetooth ranges depending on the power class of the implementation. It has three power classes, where class 2, with a range of about 10 meters is the most common. The others are class 1, up to 100 meters, and the rarely used class 3, which has a range of 10 cm, up to a maximum of 1 meter. The maximum speed of Bluetooth transfers is 723.1 kilobit/s in
version 1.1 - 1.2, and 2.1 megabit/s in version 2.0

Each Bluetooth device has a unique address, also called Bluetooth ID or device ID. This ID is usually not shown to users, as the more user friendly customizable Bluetooth name is shown
instead.

Bluetooth could also be used in home networking applications. With increasing numbers of homes having multiple PCs, the need for networks that are simple to install and maintain, is growing. There is also the commercial need to provide "information push" capabilities, which is important for handheld and other such mobile devices and this has been partially incorporated in Bluetooth. Bluetooth's main strength is its ability to simultaneously handle both data and voice transmissions, allowing such innovative solutions as a mobile hands-free headset for voice calls, print to fax capability, and automatically synchronizing PDA, laptop, and cell phone address book applications. One popular use of Bluetooth is for wireless headsets. A Bluetooth headset would have a Bluetooth radio built in, allowing it to connect to mobile phones or computers, so that people canuse the headset without connecting it with a cable.

Bluetooth is competing against two other major methods of wireless networking: IrDA and WiFi. However, WiFi is most useful as a replacement for LANs and IrDa is limited by its need for an unobstructed line-of-sight between connecting devices.

Applications
The following are the areas where Bluetooth can be used:

  • Replacing serial cables by radio links

  • "Wearable" networks/PANs

  • Desktop/Room Wireless Networking

  • HotSpot Wireless Networking

  • Medical: Transfer of measured values from training units to analytical systems, Patient data monitoring

  • Automotive: Remote control of audio/video equipment, Hands-free telephony

  • POS (Point-of-sale) payments: Payments by mobile phone

 

Bluetooth Resources:

Official Bluetooth website

Official Bluetooth Membership site

Bluetooth Spcecifications

Bluetooth Specification - A technical overview (doc)

Bluetooth resources

Intel bluetooth tutorial (pdf)

Free Bluetooth white papers

Bluetooth medical article

Bluetooth and Linux - How to's

Bluejacking

Bluedating

Bluesnarfing

Bluetooth applications and tutorial

Bluetooth Tutorial