Blue Tooth

Bluetooth technology is how devices such as cell phones, computers, and PDAs can be interconnected wirelessly. This website will explain how the Bluetooth technology works, discuss its evolution and many uses.

Bluetooth - Introduction
A wireless personal area network (WPAN) technology from the Bluetooth Special Interest Group (www.bluetooth.com) founded in 1998 by Ericsson, IBM, Intel, Nokia and Toshiba. Bluetooth is an open standard for short-range transmission of digital voice and data that supports point-to-point and multipoint applications. Most of the original Bluetooth applications were developed with cell phones in mind, as a means of providing a wireless connection to a headset or a hands-free system. See WPAN.

Bluetooth applications provide a way to connect and exchange information between devices like personal digital assistants (PDAs), mobile phones, laptops, PCs, printers, and digital cameras via a secure, low-cost, globally available short range radio frequency.

WPANWPAN (Wireless Personal Area Network)

A wireless network that is typically limited to a small cell radius. In an office environment, a WPAN can be used to transfer data between a handheld device and desktop machine or printer. For example, a mobile user could download e-mail or Web data into a dual mode smart phone or PDA and then exchange that data with a machine in the office. In the home, WPANs provide cable-free connections for alarms, appliances and entertainment systems.

Specifications

Bluetooth provides up to 720 Kbps data transfer within a range of 10 meters, with a low-cost transceiver microchip in each device, and up to 100 meters with a power boost. Unlike IrDA, which requires that devices be aimed at each other (line of sight), Bluetooth uses omni directional radio waves that can transmit through walls and other non-metal barriers. Bluetooth transmits in the unlicensed 2.4GHz band and uses a frequency hopping spread spectrum technique that changes its signal 1600 times per second. Upon interference from other devices, the transmission slows, but not does stop.

Bluetooth technology allows devices to talk to others in their range as long as they are within up to 100 meters (328 feet) of each other, dependent on the power class of the product. Products are available in one of three power classes:

1. Class 1 (100 mW) [still readily available]: has the longest range of up to 100 meters (328 ft).blockquote>
2. Class 2 (2.5 mW) [most common]: allows a quoted transmission distance of 10 meters (33 ft).blockquote>
3. Class 3 (1 mW) [rare]: allows transmission between 10 cm (3.9 in) and 1 meter (3.3 ft).

Origin of the name and logo

The Bluetooth system was named after Danish king Harald Blåtand (Harold I of Denmark in English), King of Denmark and Norway from 935 and 936, respectively, to 940. Blåtand (or Bluetooth) is known for his unification of warring tribes from Denmark (including Skåne, present-day Sweden, where the Bluetooth technology was invented) and Norway. Like its namesake, Bluetooth was intended to unify different technologies like computers and mobile phones. The Bluetooth logo merges the Nordic runes analogous to the modern Latin H and B.

This is the official story. More likely, Bluetooth was named after the Harald Blåtand portrayed in the best-selling Swedish Viking-inspired novel The Long Ships by Frans Gunnar Bengtsson. The name originated as a code for the project but stuck as the official name.

Bluetooth Applications

Wireless Networking between desktops and other workstations (laptops or desktops) in a confined space, where little bandwidth is required

Bluetooth peripherals such as printers, mice and keyboards.

Bluetooth cell phones have been sold in large numbers, and are able to connect to computers, personal digital assistants (PDAs) and, specifically, to hands-free devices. The standard also includes support for more powerful, longer-range devices suitable for constructing wireless LANs.

Transfer of files (images, mp3s, etc.) between mobile phones, personal digital assistants (PDAs), and computers via OBEX

Allows certain mp3 players and Digital Cameras to transfer files to and from computers

Bluetooth headsets for mobile phones & Smartphones.

Medical applications - Advanced Medical Electronics Corporation is working on several devices to enable easier transfer of critical medical information

Certain GPS receivers transfer NMEA data via Bluetooth.

• Bluetooth car kits - Acura was the first motor vehicle manufacturer to install handsfree Bluetooth technology in their vehicles with the 2004 Acura TL. BMW later added it as an option on its 3 Series, 5 Series, 7 Series, and X5 vehicles. Other manufacturers have followed suit, with many vehicles, including the 2004 Toyota Prius and the 2004 Lexus LS 430. The Bluetooth car kits allow users with Bluetooth-equipped cell phones to make use of certain features of the phone, while the phone itself is stowed away. Companies like Parrot or Motorola manufacture Bluetooth hands-free car kits for well-known brand car manufacturers.

Certain data logging equipment transmits data to a computer via Bluetooth.

For remote controls where infrared was traditionally used.

Hearing aids - Starkey Laboratories have created a device to plug into some hearing aids.

Communication & Connection
A Bluetooth device playing the role of the "master" can communicate with up to 7 devices playing the role of the "slave". This network of " up to 8 devices" (1 master + 7 slaves) is called a piconet.

At any given time, data can be transferred between the master and 1 slave; but the master is able to switch rapidly from slave to slave in a round-robin fashion. (Simultaneous transmission from the master to multiple slaves is possible, but is not a commonly implemented practice.) Devices are able to switch roles (between master and slave) at any time.

Bluetooth specifications allow connecting two or more piconets together to form a scatternet. A device can act as a bridge between two piconets by acting as a master in one while playing the role of the slave in another. These devices are not yet readily available on the market but are scheduled to appear within the next 2 years (2007).

Piconet

A piconet is an ad-hoc network of computing devices using Bluetooth technology protocols to allow one master device to interconnect with up to seven active slave devices (using a three-bit MAC address). As need arises, slave devices can remain inactive, or parked, to adhere to the limit of seven. The master device can bring parked devices back into active status at any time, swapping out unnecessary slave devices.

Round-Robin Scheduling

The Round-robin system is one of the simplest scheduling algorithms for processes in an operating system. This system assigns time slices to each process in an equal portion, and in order, handling all processes as having the same priority. Round-robin scheduling is both easy to implement and easy to understand, and starvation-free. Round-robin scheduling can also be applied to other scheduling problems, such as network scheduling.

The name comes from the round-robin principle known in other fields, wherein each person is allotted an equal share, in turn, of a community object.

Scatternet

A scatternet is set of piconets connected through sharing devices.

Although the scatternet system was proposed in the standards, it is not a well-developed option today. Most researchers have largely concentrated on theoretical concepts, proposing and simulating algorithms for instance, but not actually implementing them. The BTnode project at ETH Zurich exhibits the first instances of actual scatternet implementation.

Setting up connections
Any Bluetooth device will transmit the following sets of information on demand:

Device Name

Device Class

List of services

• Technical information (e.g. device features, manufacturer, Bluetooth specification, clock offset)

Any device may perform an "inquiry" to find other devices to which to connect, and any device can be configured to respond to such inquiries. However, if the device trying to connect knows the address of the device to which it is attempting connection, there will always be a response to a direct connection requests. Use of the device's services; however, may require pairing or acceptance but the connection itself can be started by any device and will be held until it goes out of range. Some devices can only be connected to one device at a time and connecting to them will prevent other connections or inquiries.

Every device has a unique 48-bit address. However, these addresses are generally not shown in inquiries. Instead, friendly "Bluetooth names" are used which can be set by the user, and will appear when another user scans for devices. Most phones set the Bluetooth name to default to the manufacturer and model of the phone. It is also common for both phones and laptops to only show the Bluetooth name and require special programs to access additional information. This can get confusing as there could be several phones in range named "T610" for example. On Nokia phones the Bluetooth address may be found by entering ">2820#". On computers running Linux the address and class of a USB Bluetooth dongle may be found by entering "hciconfig hci0 class" as root ("hci0" may need to be replaced by another device name).

Every device also has a 24-bit class identifier. This provides information on what kind of device you are using (Phone, Smartphone, Computer, Headset, etc), which is also transmitted when inquiries are made. On some phones this information is translated into an icon displayed beside the device's name.

Bluetooth devices can also transmit a list of services if requested by another device; this includes extra information such as the name of the service and what channel it is on. These channels are virtual and have nothing to do with the frequency of the transmission, much like TCP ports. A device can therefore have multiple identical services.

Pairing
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 to discourage others from listening in. This encryption can be turned off and passkeys stored on the device's file system, rather than the Bluetooth chip, to enable future interactions. Because the Bluetooth address is permanent, a pairing will be preserved even if the Bluetooth name is changed. Pairings will usually be required before a device allows remote access to its services; however, pairs can be deleted at any time by either device. Some devices, such as Sony Ericsson phones, will usually accept OBEX business cards and notes without any pairing or prompts. Certain printers and access points will allow any device to use its services by default, much like unsecured Wi-Fi networks.

Future of Bluetooth
One of the ways Bluetooth technology may become useful is in Voice-over IP (VOIP). As Voice-over IP becomes more widespread, companies may find it unnecessary to employ telephones physically similar to today's analogue telephone hardware. Bluetooth may end up being used for communication between cordless phones and computers listening for Voice-over IP, with an infrared Peripheral Component Interconnect (PCI) card acting as a base for the cordless phone. The cordless phone would then only require a cradle for charging. Bluetooth would allow the cordless phone to remain operational for a reasonably long period of time.

In May 2005, the Bluetooth Special Interest Group (SIG) announced its intent to work with UWB manufacturers to develop a next-generation Bluetooth technology using UWB technology and delivering UWB speeds. This will enable Bluetooth technology to be used to deliver high speed network data at exchange rates required for wireless VOIP, music, and video applications.

Bluetooth may also be used for remote sales technology, allowing wireless access to vending machines and other commercial enterprises.

Competing Technologies

Bluetooth - industrial specification for wireless personal area networks (PANs)

European Installation Bus - intelligent electrical installation networking

HomePlug - powerline protocol

IrDA - industry standard infrared protocol

nanoNET - proprietary set of wireless sensor protocols, designed to compete with ZigBee

OBEX - communications protocol that facilitates the exchange of binary objects between devices

RadioRa - proprietary two-way RF protocol, developed by Lutron for use in residential lighting control

TinyOS - mesh network OS using the NesC language

Topdog - proprietary protocol for wireless networking, for use in residential and commercial lighting control

UPB - powerline protocol that offers improved performance and reliability over X10

Wi-Fi - product compatibility standards for wireless local area networks (WLANs)

Wireless USB - wireless extension to USB

X10 - powerline protocol

Z-wave - proprietary protocol for wireless home control networking

ZigBee - set of high level protocols designed for low power digital radios

Accessories for Bluetooth phones

Talk to the Dashboard

When paired with a cell phone, the CCM Blue Warrior Car Kit (3.5 stars out of 5, $80) becomes a speakerphone that plugs into your car's power adapter. The noise-canceling microphone reduces background sounds effectively, and the large buttons make adjusting speaker volume easy. The Blue Warrior is far from sleek or sexy, but it's certainly the most practical device I tested.

Tiny Tune Box for Phone Fiends

Part MP3 music player and part hands-free phone headset, the compact, very lightweight Sony Ericsson HBM-30 (3 stars out of 5, $109) is a cute little gadget that lets you take calls with minimal interruption of your music. It automatically pauses music for an incoming call, and you speak into its built-in microphone (the HBM-30 is meant to be worn around your neck or clipped to your clothes) and listen to the caller through the stereo headphones.

While it offers good-quality sound for both music and phone calls, and it paired easily with my Sony Ericsson T637 Bluetooth phone, I would definitely replace the headphones with a more comfortable set. In addition, the battery chamber cover was extremely difficult to remove. In short: cool concept, lukewarm execution.

A Pen for Your Thoughts

With Nokia's SU-1B Digital Pen (3.5 stars out of 5, $249), I doodled and made handwritten notes in ink on a special notepad and transmitted them from the pen to my Bluetooth phone. I then sent my scribbles from the phone to friends via Multimedia Messaging System. As an alternative to typing on a cell phone keypad, this pen is a handy--though pricey--tool for MMS addicts. The pen can transfer drawings and notes to a PC, too, but only through a USB connection. (You can save your jottings in formats like BMP and JPEG, but you can't easily convert them to text.)

Show Your Phone Snapshots on TV

Want to make a slide show out of your camera-phone photos the next time your friends visit? Nokia's SU-2 Image Viewer (2.5 stars out of 5, $90) lets you display the shots on a TV or projector. Hook this square gray thingamajig to your TV's RCA input via the built-in cable, beam the pictures wirelessly to the SU-2 from your Bluetooth-enabled phone, and let the photo fest begin.

The unit is easy to set up and use, but it displays resolutions only up to 640 by 480; if you have a newer phone that takes higher-resolution photos, you won't be able to use this device. And 640-by-480-pixel photos will look blocky on a TV screen, no matter what. If your phone can send batches of photos (my T637 couldn't do it), you can create a slide show; Nokia says you also can use sequentially beamed shots.

Security
Security measures

Bluetooth uses the SAFER+ algorithm for authentication and key generation. The E0 stream cipher is used for encrypting packets, making eavesdropping on bluetooth-enabled devices more difficult.

Security concerns

2003: In November 2003, Ben and Adam Laurie from A.L. Digital Ltd. discovered that serious flaws in Bluetooth security lead to the disclosure of personal data (see http://bluestumbler.org). It should be noted however, that the reported security problems concerned poor implementations of Bluetooth, rather than the protocol itself.

In a subsequent experiment, Martin Herfurt from the trifinite group was able to do a field-trial at the CeBIT fairgrounds showing the importance of this security problem to the world. A new attack called BlueBug was used for this experiment.

2004: In April 2004, security consultants @Stake revealed a security flaw that made it possible to crack 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 purported virus using Bluetooth appeared for the Symbian OS and spread itself among mobile phones. The virus was first described by Kaspersky Lab and required users to confirm the installation of unknown software before it could propagate.

Note: This virus was written as proof-of-concept by a group of virus writers known as 29a and sent to anti-virus groups. Thus it should be regarded as a potential (but NOT actual) security threat to Bluetooth or Symbian OS as the virus has never actually spread.

In August 2004, a world-record-setting experiment (see also Bluetooth sniping) showed that the range of class 2 Bluetooth radios could be extended to 1.78 km (1.08 mile) with directional antennas. This posed a potential security threat as it enabled attackers to access vulnerable Bluetooth-devices from a distance beyond expectation. However, such experiments will not work using signal amplifiers as the attacker must also be able to receive information from its victim in order to set up a connection. No attack can be made against a Bluetooth device unless the attacker has knowledge of the device’s Bluetooth address and the channel on which it tramists.

2005: In June 2005, Yaniv Shaked and Avishai Wool published the paper "Cracking the Bluetooth PIN1", which showed both passive and active methods for obtaining the PIN for a Bluetooth Link. The passive attack would allow a suitably equipped attacker to eavesdrop on communications and spoof if they were present at the time of initial pairing. The active method made use of a specially constructed message that must be inserted at a specific point in the protocol, to make the master and slave repeat the pairing process. Following this insertion, the first method would be used to crack the PIN. This attack's major weakness is that it requires the user of the devices under attack to re-enter their PIN during the attack when their device prompts them to do so. In addition, the active attack would most likely require custom hardware, as most commercially available Bluetooth Devices are not capable of the timing necessary.

In August 2005, police in Cambridgeshire, England, issued warnings about thieves using Bluetooth-enabled phones to track other devices left in cars. Police advised users to ensure any mobile networking connections are de-activated if laptops and other devices are left in this way. However, it is always recommended to avoid leaving valuable devices unattended in automobiles.


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