What is Bluetooth?

Red Flower · #1 Wednesday, July 22, 2009

What is Bluetooth?

Bluetooth is an open specification for wireless short range communications of data and voice between both mobile and stationary devices. It was developed by Ericsson Inc., Intel Corp., Nokia Corp. and Toshiba. It was designed to set a standard for cable free connectivity between mobile phones, mobile PCs, handheld computers and other peripherals. It offers better signal range than standard wireless devices.

Bluetooth offers a range of 10 meters (32 feet) and a low speed (up to 1Mbps) wireless transmission of digital voice and data in the unlicensed 2.4GHz band. Bluetooth technology is an ad hoc technology that requires no fixed infrastructure and is simple to install and set up. Bluetooth wireless technology is the most widely supported, versatile, and secure wireless standard on the market today.

Bluetooth is used on many devices such as keyboards and mice, cell phone headsets, GPS systems for your car and Ipod transmitters

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.

The manufacturer of each product determines the security mode of their product. Devices and services also have different security levels. For devices, there are two levels of security: trusted device and untrusted devices. A trusted device, having been paired with one's other device, has unrestricted access to all services. With regard to services, three security levels are defined: services that require authorization and authentication, services that require authentication only and services that are open to all devices.

ravaila · #2 Wednesday, July 22, 2009

How Bluetooth Creates a Connection
*Bluetooth takes small-area networking to the next level by removing the need for user intervention and keeping transmission power extremely low to save battery power. Picture this: You're on your Bluetooth-enabled cell phone, standing outside the door to your house. You tell the person on the other end of the line to call you back in five minutes so you can get in the house and put your stuff away. As soon as you walk in the house, the map you received on your cell phone from your car's Bluetooth-enabled GPS system is automatically sent to your Bluetooth-enabled computer, because your cell phone picked up a Bluetooth signal from your PC and automatically sent the data you designated for transfer. Five minutes later, when your friend calls you back, your Bluetooth-enabled home phone rings instead of your cell phone. The person called the same number, but your home phone picked up the Bluetooth signal from your cell phone and automatically re-routed the call because it realized you were home. And each transmission signal to and from your cell phone consumes just 1 milliwatt of power, so your cell phone charge is virtually unaffected by all of this activity.

Bluetooth is essentially a networking standard that works at two levels:

It provides agreement at the physical level -- Bluetooth is a radio-frequency standard.

It provides agreement at the protocol level, where products have to agree on when bits are sent, how many will be sent at a time, and how the parties in a conversation can be sure that the message received is the same as the message sent.

The big draws of Bluetooth are that it is wireless, inexpensive and automatic. There are other ways to get around using wires, including infrared communication. Infrared (IR) refers to light waves of a lower frequency than human eyes can receive and interpret. Infrared is used in most television remote control systems. Infrared communications are fairly reliable and don't cost very much to build into a device, but there are a couple of drawbacks. First, infrared is a "line of sight" technology. For example, you have to point the remote control at the television or DVD player to make things happen. The second drawback is that infrared is almost always a "one to one" technology. You can send data between your desktop computer and your laptop computer, but not your laptop computer and your PDA at the same time. (See How Remote Controls Work to learn more about infrared communication.)

These two qualities of infrared are actually advantageous in some regards. Because infrared transmitters and receivers have to be lined up with each other, interference between devices is uncommon. The one-to-one nature of infrared communications is useful in that you can make sure a message goes only to the intended recipient, even in a room full of infrared receivers.

Bluetooth is intended to get around the problems that come with infrared systems. The older Bluetooth 1.0 standard has a maximum transfer speed of 1 megabit per second (Mbps), while Bluetooth 2.0 can manage up to 3 Mbps. Bluetooth 2.0 is backward-compatible with 1.0 devices.

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