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BLUETOOTH
Virtually everyone has a Bluetooth enabled phone, but do you know enough about it?

Chances are you’ll have a tough time finding a new cell phone that doesn't have Bluetooth today. Yet, not many of us use the technology, much less understand it. Bluetooth has risen out of a simple enough problem – that of communication. And it communicates in ways that are changing the way we network on the most basic, personal level.

What is, and who was, Bluetooth
On a more academic level, you could say that Bluetooth is an industrial specification for wireless personal area networks, also known as IEEE 802.15.1. This technology provides a way to connect and exchange information between devices like personal digital assistants, mobile phones, laptops, computers, printers, digital cameras and video game consoles via a secure, globally unlicensed short range radio frequency.

The name Bluetooth is derived from the name of a 10th century king of Denmark, Harald Bluetooth. According to the inventors of the technology, Harald engaged in diplomacy that led warring parties to negotiate with each other, making Bluetooth a fitting name for their technology, which allows different devices to talk to each other. The Bluetooth logo is based on the runic symbols for H and B, from the king’s name.

The communication problem
When any two devices need to talk to each other, they have to agree on a number of points before the conversation can begin. The first point of agreement is physical: Will they talk over wires, or through some form of wireless signals? How much data will be sent at a time? For instance, serial ports send data one bit at a time, while parallel ports send several bits at once. How will they speak to each other? All of the parties in an electronic discussion need to know what the bits mean and whether the message they receive is the same message that was sent. This means developing a set of commands and responses known as a protocol.

The Bluetooth solution
Bluetooth solves these problems by communicating wirelessly, and doing so by using the minimum of power. This means that cell phones and other devices can send and receive signals without compromising on their limited battery charges.

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

1. It provides agreement at the physical level – Bluetooth is a radio-frequency standard.
2. 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.

More than infrared
There are other ways to get around using wires, including infrared communication. It 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 to make things happen. The second drawback is that it is almost always a ‘one to one’ technology. You can send data between your desktop and your laptop, but not your laptop and your PDA at the same time.

One of the ways Bluetooth devices avoid interfering with other systems is by sending out very weak signals of about one milliwatt. By comparison, the most powerful cell phones can transmit a signal of three watts. The low power limits the range of a Bluetooth device to about ten meters, cutting the chances of interference between your computer system and your portable telephone or television. Even with the low power, Bluetooth doesn't require line of sight between communicating devices. The walls in your house won't stop a Bluetooth signal, making the standard useful for controlling several devices in different rooms.

Less than Wi-Fi
Bluetooth is acceptable for situations when two or more devices are in close proximity with each other and you don’t require high bandwidth. It is most commonly used with cell phones, either using a Bluetooth headset or transferring files from phones to computers. Because it uses short-range radio frequencies it is not as effective for setting up networks that can be accessed from remote locations. Wi-Fi technology is better suited for this purpose.

Wi-Fi uses the same radio frequencies as Bluetooth, but with higher power consumption resulting in a stronger connection. It is better suited for setting up networks since it is a faster connection and has increased security over Bluetooth. Wi-Fi is popular among the computing world, virtually all new laptop computers come with Wi-Fi built in, and all desktop computers can be adapted to have a Wi-Fi connection. Recently a few new cell phones have come out with Wi-Fi too.

Up in the air
The problems of the world soon caught up with Bluetooth. In 2004 the first purported virus using Bluetooth to spread itself among mobile phones appeared in the Symbian operating system. It was first described by Kaspersky Lab and requires users to confirm the installation of unknown software before it can propagate itself.

In 2004, an experiment showed that the range of class two Bluetooth radios could be extended to 1.78km with directional antennas. This poses a potential security threat as it enables attackers to access vulnerable Bluetooth devices from a distance much beyond expectation.

In 2005, police in Cambridgeshire, England, issued warnings about thieves using Bluetooth-enabled phones to track other devices left in cars. Police advise users to ensure any mobile networking connections are de-activated if laptops and other devices are left in this way. The best solution, of course, is to not leave any valuable devices in your car.

Where we will go
Future versions of Bluetooth, already in the pipeline, will adopt ultra wideband (UWB) radio technology. This will enable very fast data transfers, while building on the very low power modes of Bluetooth. The combination of a radio using little power when no data is transmitted and a high data rate radio used to transmit bulk data could be the start of software radios. Bluetooth, given its worldwide regulatory approval, low power operation and robust data transmission capabilities, provides an excellent signalling channel to enable this soft radio concept.

At the same time, Bluetooth technology will continue catering to the needs of very low power applications such as mice, keyboards and mono headsets, enabling devices to select the most appropriate physical radio for the application requirements, thereby offering the best of both worlds.