Bluetooth provides a way to connect and exchange information between devices like personal digital assistants (PDAs), mobile phones, laptops, PCs, printerss and digital cameras via a secure, low-cost, globally available short range radiofrequency.
Bluetooth lets these devices talk to each other when they come in range, even if they're not in the same room, as long as they are within 10 metres of each other.
It is a wireless radio standard primarily designed for low power consumption, with a short range (from 10 up to 100 meters) and with a low-cost transceivermicrochip in each device.
It can be used to wirelessly connect peripherals like printers or keyboards to computers, or to have PDAs communicate with other nearby PDAs or computers. Cell phones with integrated Bluetooth technology have also been released in large numbers, that can connect to computer, PDAs and, specifically, to handsfree. Toyota's 2004 Prius is the first car that supports the Bluetooth system. Passengers of the Prius can use their Bluetooth-enabled cellphone via the car's audio system without taking the phone out of their pocket. The 2004 Lexus LS 430 offers similar Bluetooth functionality.
However, the standard also includes support for more powerful longer-range devices suitable for constructing a wireless LAN. Every Bluetooth device can simultaneously maintain up to 7 connections. Every device can be configured to constantly announce its presence to nearby devices, in order to establish a connection. It is also possible to password protect a connection between two devices, so that no others can listen in.
The protocol operates in the license-free ISM band at 2.45 GHz. It reaches speeds of 723.1 kbit/s. In order to avoid interfering with other protocols which may use the 2.45 GHz band, the Bluetooth protocol divides the band into 79 channels and changes channels up to 1600 times per second.
Bluetooth should not be compared to Wi-Fi, a faster protocol requiring more expensive hardware that covers greater distances and uses the same frequency range. While Bluetooth is a cable replacement creating personal area networking between different devices, Wi-Fi is a cable replacement for local area network access. They serve different purposes.
Many USB Bluetooth adapters are available, some of which also include an IrDA adapter.
This channel could be used for advertising bluetooth service profiles offered by various devices to very high volumes of Bluetooth devices simultaneously, since there is no need to do the handshaking with every device. Currently the handshaking process takes approximately one second.
Unencrypted information such as realtime public transport timetables, basic traffic congestion information and advanced traffic guidance directions can be transmitted to devices passing each other even at high velocities.
In April 2004, security consultants @Stake revealed a security flaw that makes it possible to hack into conversations on Bluetooth based wireless headsets by reverse engineering the PIN.
This is one of a number of concerns that have been raised over the security of Bluetooth communications. In 2004 the first virus using Bluetooth to spread itself among mobile phones appeared for the Symbian OS
