   #copyright

Bluetooth

2007 Schools Wikipedia Selection. Related subjects: Electricity and
Electronics; Engineering

   Bluetooth is an industrial specification for wireless personal area
   networks (PANs). Bluetooth provides a way to connect and exchange
   information between devices such as mobile phones, laptops, PCs,
   printers, digital cameras, and video game consoles over a secure,
   globally unlicensed short-range radio frequency. The Bluetooth
   specifications are developed and licensed by the Bluetooth Special
   Interest Group.

Uses

   A typical Bluetooth mobile phone headset
   A typical Bluetooth mobile phone headset

   Bluetooth is a radio standard and communications protocol primarily
   designed for low power consumption, with a short range
   (power-class-dependent: 1 meter, 10 meters, 100 meters) based on
   low-cost transceiver microchips in each device.

   Bluetooth lets these devices communicate with each other when they are
   in range. The devices use a radio communications system, so they do not
   have to be in line of sight of each other, and can even be in other
   rooms, as long as the received transmission is powerful enough.
    Class  Maximum Permitted Power
           ( mW/ dBm)                 Range
                                  (approximate)
   Class 1 100 mW (20 dBm)        ~100 meters
   Class 2 2.5 mW (4 dBm)         ~10 meters
   Class 3 1 mW (0 dBm)           ~1 meter

Bluetooth profiles

   In order to use Bluetooth, a device must be compatible with certain
   Bluetooth profiles. These define the possible applications and uses.

List of applications

   More prevalent applications of Bluetooth include:
     * Wireless control of and communication between a cell phone and a
       hands-free headset or car kit. This was one of the earliest
       applications to become popular.
     * Wireless networking between PCs in a confined space and where
       little bandwidth is required.
     * Wireless communications with PC input and output devices, the most
       common being the mouse, keyboard and printer.
     * Transfer of files between devices with OBEX.
     * Transfer of contact details, calendar appointments, and reminders
       between devices with OBEX.
     * Replacement of traditional wired serial communications in test
       equipment, GPS receivers, medical equipment and traffic control
       devices.
     * For controls where infrared was traditionally used.
     * Sending small advertisements from Bluetooth enabled advertising
       hoardings to other, discoverable, Bluetooth devices.
     * Seventh-generation game consoles—Nintendo Wii, Sony PlayStation
       3—use Bluetooth for their respective wireless controllers.

Bluetooth vs. Wi-Fi in networking

   Bluetooth and Wi-Fi both have their places in today's offices, homes,
   and on the move: setting up networks, printing, or transferring
   presentations and files from PDAs to computers.

Bluetooth

   Bluetooth is implemented in a variety of new products such as phones,
   printers, modems, and headsets. Bluetooth is acceptable for situations
   when two or more devices are in proximity to each other and don't
   require high bandwidth. Bluetooth is most commonly used with phones and
   hand-held computing devices, either using a Bluetooth headset or
   transferring files from phones/PDAs to computers.

   Bluetooth also simplifies the discovery and setup of services.
   Bluetooth devices advertise all services they provide. This makes the
   utility of the service that much more accessible, without the need to
   worry about network addresses, permissions and all the other
   considerations that go with typical networks.

Wi-Fi

   Wi-Fi is more analogous to the traditional Ethernet network and
   requires configuration to set up shared resources, transmit files, set
   up audio links (for example, headsets and hands-free devices). It uses
   the same radio frequencies as Bluetooth, but with higher power output
   resulting in a stronger connection. Wi-Fi is sometimes, but rarely,
   called "wireless Ethernet." Although this description is inaccurate, it
   provides an indication of its relative strengths and weaknesses. Wi-Fi
   requires more setup, but is better suited for operating full-scale
   networks because it enables a faster connection, better range from the
   base station, and better security than Bluetooth.

   One method for comparing the efficiency of wireless transmission
   protocols such as Bluetooth and Wi-Fi is spatial capacity, or bits per
   second per square meter.

Computer requirements

   A typical Bluetooth USB dongle (BCM2045A), shown here next to a metric
   ruler
   A typical Bluetooth USB dongle (BCM2045A), shown here next to a metric
   ruler
   An internal notebook Bluetooth card (14×36×4 mm)
   An internal notebook Bluetooth card (14×36×4 mm)

   A personal computer must have a Bluetooth dongle in order to be able to
   communicate with other Bluetooth devices (such as mobile phones, mice
   and keyboards). While some portable computers and fewer desktop
   computers already contain an internal Bluetooth dongle, most computers
   require an external USB Bluetooth dongle. Unlike its predecessor, IrDA,
   in which each device requires a separate dongle, multiple Bluetooth
   devices can communicate with a computer over a single dongle.

Operating system support

   Linux provides two Bluetooth stacks, with the BlueZ stack included with
   most Linux kernels. It was originally developed by Qualcomm and Affix.
   BlueZ supports all core Bluetooth protocols and layers.

   Only Microsoft Windows XP Service Pack 2 and later versions of Windows
   have native support for Bluetooth. Previous versions required the users
   to install their Bluetooth dongles' own drivers, which tended to clash
   with the operating system. Microsoft's own Bluetooth dongles (that are
   packaged with their Bluetooth computer devices) have no external
   drivers and thus require at least Windows XP Service Pack 2.

Specifications and features

   The Bluetooth specification was developed in 1994 by Sven Mattisson and
   Jaap Haartsen, who were working for Ericsson Mobile Platforms in Lund,
   Sweden. The specifications were formalized by the Bluetooth Special
   Interest Group ( SIG). The SIG was formally announced on May 20, 1998.
   Today it has over 7000 companies worldwide. It was established by
   Ericsson, Sony Ericsson, IBM, Intel, Toshiba, and Nokia, and later
   joined by many other companies. Bluetooth is also known as IEEE
   802.15.1.

Bluetooth 1.0 and 1.0B

   Versions 1.0 and 1.0B had many problems, and manufacturers had
   difficulties making their products interoperable. Versions 1.0 and 1.0B
   also had mandatory Bluetooth hardware device address (BD_ADDR)
   transmission in the handshaking process, rendering anonymity impossible
   at a protocol level, which was a major setback for services planned to
   be used in Bluetooth environments, such as Consumerium.

Bluetooth 1.1

     * Many errors found in the 1.0B specifications were fixed.
     * Added support for non-encrypted channels.
     * Received Signal Strength Indicator ( RSSI).

Bluetooth 1.2

   This version is backward-compatible with 1.1 and the major enhancements
   include the following:
     * Faster Connection and Discovery
     * Adaptive frequency-hopping spread spectrum (AFH), which improves
       resistance to radio frequency interference by avoiding the use of
       crowded frequencies in the hopping sequence.
     * Higher transmission speeds in practice, up to 721 kbps, as in 1.1.
     * Extended Synchronous Connections (eSCO), which improve voice
       quality of audio links by allowing retransmissions of corrupted
       packets.
     * Host Controller Interface (HCI) support for three-wire UART.

Bluetooth 2.0

   This version, specified in November 2004, is backward-compatible with
   1.1. The main enhancement is the introduction of an enhanced data rate
   (EDR) of 3.0 Mbps. This has the following effects:
     * Three times faster transmission speed—up to 10 times in certain
       cases (up to 2.1 Mbit/s).
     * Lower power consumption through a reduced duty cycle.
     * Simplification of multi-link scenarios due to more available
       bandwidth.
     * Further improved ( bit error rate) performance.

Bluetooth 2.1

   Bluetooth Core Specification Version 2.1 + EDR, is fully
   backward-compatible with 1.1, and will be adopted by the Bluetooth SIG
   once interoperability testing has completed. This specification
   includes the following features:
     * Extended inquiry response: provides more information during the
       inquiry procedure to allow better filtering of devices before
       connection. This information includes the name of the device, a
       list of services the device supports, as well as other information
       like the time of day, and pairing information.

     * Sniff subrating: reduces the power consumption when devices are in
       the sniff low-power mode, especially on links with asymmetric data
       flows. Human interface devices (HID) are expected to benefit the
       most, with mouse and keyboard devices increasing the battery life
       from 3 to 10 times those currently used.

     * Encryption Pause Resume: enables an encryption key to be refreshed,
       enabling much stronger encryption for connections that stay up for
       longer than 24 hours.

     * Secure Simple Pairing: radically improves the pairing experience
       for Bluetooth devices, while increasing the use and strength of
       security. It is expected that this feature will significantly
       increase the use of Bluetooth.

Future of Bluetooth

     * Broadcast Channel: enables Bluetooth information points. This will
       drive the adoption of Bluetooth into cell phones, and enable
       advertising models based around users pulling information from the
       information points, and not based around the intrusive object push
       model that is used in a limited way today.

     * Topology Management: enables the automatic configuration of the
       piconet topologies especially in scatternet situations that are
       becoming more common today. This should all be invisible to the
       users of the technology, while also making the technology just
       work.

     * Alternate MAC PHY: enables the use of alternative MAC and PHY's for
       transporting Bluetooth profile data. The Bluetooth Radio will still
       be used for device discovery, initial connection and profile
       configuration, however when lots of data needs to be sent, the high
       speed alternate MAC PHY's will be used to transport the data. This
       means that the proven low power connection models of Bluetooth are
       used when the system is idle, and the low power per bit radios are
       used when lots of data needs to be sent.

     * QoS improvements: enable audio and video data to be transmitted at
       a higher quality, especially when best effort traffic is being
       transmitted in the same piconet.

   Bluetooth technology already plays a part in the rising Voice over IP
   (VOIP) scene, with Bluetooth headsets being used as wireless extensions
   to the PC audio system. As VOIP becomes more popular, and more suitable
   for general home or office users than wired phone lines, Bluetooth may
   be used in cordless handsets, with a base station connected to the
   Internet link.

   The next version of Bluetooth after v2.1, code-named Seattle, that will
   be called Bluetooth 3.0, has many of the same features, but is most
   notable for plans to adopt ultra-wideband (UWB) radio technology. This
   will allow Bluetooth use over UWB radio, enabling very fast data
   transfers of up to 480 Mbit/s, synchronizations, and file pushes, while
   building on the very low-power idle modes of Bluetooth. The combination
   of a radio using little power when no data is transmitted and a high
   data rate radio to transmit bulk data could be the start of software
   radios. Bluetooth, given its world-wide regulatory approval, low-power
   operation, and robust data transmission capabilities, provides an
   excellent signaling channel to enable the soft radio concept.

   On 28 March 2006, the Bluetooth Special Interest Group announced its
   selection of the WiMedia Alliance Multi-Band Orthogonal Frequency
   Division Multiplexing (MB-OFDM) version of UWB for integration with
   current Bluetooth wireless technology.

   UWB integration will create a version of Bluetooth wireless technology
   with a high-speed/high-data-rate option. This new version of Bluetooth
   technology will meet the high-speed demands of synchronizing and
   transferring large amounts of data, as well as enabling high-quality
   video and audio applications for portable devices, multi-media
   projectors and television sets, and wireless VOIP.

   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.

   The Bluetooth SIG have also announced that they are looking to include
   Ultra Low Power use cases into Bluetooth, enabling a whole new set of
   use cases. This inculdes watches displaying Caller ID information,
   sports sensors monitoring your heart rate during exercise, as well as
   medical devices. The Medical Devices Working Group is also creating a
   medical devices profile and associated protocols to enable this market.

   The Draft High Speed Bluetooth Specification is available at the
   Bluetooth website.

Technical information

Communication and connection

   A master Bluetooth device can communicate with up to seven devices.
   This network group of up to eight devices is called a piconet.

   A piconet is an ad-hoc computer network, using Bluetooth technology
   protocols to allow one master device to interconnect with up to seven
   active devices. Up to 255 further devices can be inactive, or parked,
   which the master device can bring into active status at any time.

   At any given time, data can be transferred between the master and one
   other device. However, the master switches rapidly from device to
   another in a round-robin fashion. (Simultaneous transmission from the
   master to multiple other devices is possible, but not used much.)
   Either device can switch roles and become the master at any time.

   Bluetooth specification allows connecting two or more piconets together
   to form a scatternet, with some devices acting as a bridge by
   simultaneously playing the master role and the slave role in one
   piconet. These devices are planned for 2007.

Setting up connections

   Any Bluetooth device will transmit the following sets of information on
   demand:
     * Device name.
     * Device class.
     * List of services.
     * Technical information, for example, 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, it always responds to direct connection requests and transmits
   the information shown in the list above if requested. Use of device
   services may require pairing or acceptance by its owner, but the
   connection itself can be started by any device and held until it goes
   out of range. Some devices can be connected to only one device at a
   time, and connecting to them prevents them from connecting to other
   devices and appearing in inquiries until they disconnect from the other
   device.

   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. This name appears when another user
   scans for devices and in lists of paired devices.

   Most phones have the Bluetooth name set to the manufacturer and model
   of the phone by default. Most phones and laptops show only the
   Bluetooth names and special programs that are required to get
   additional information about remote devices. This can be confusing as,
   for example, there could be several phones in range named T610 (see
   Bluejacking).

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 so that no one can
   listen in. The encryption can, however, be turned off, and passkeys are
   stored on the device file system, not on the Bluetooth chip itself.
   Since the Bluetooth address is permanent, a pairing is preserved, even
   if the Bluetooth name is changed. Pairs can be deleted at any time by
   either device. Devices generally require pairing or prompt the owner
   before they allow a remote device to use any or most of their services.
   Some devices, such as Sony Ericsson phones, usually accept OBEX
   business cards and notes without any pairing or prompts.

   Certain printers and access points allow any device to use its services
   by default, much like unsecured Wi-Fi networks. Pairing algorithms are
   sometimes manufacturer-specific for transmitters and receivers used in
   applications such as music and entertainment.

Air interface

   The protocol operates in the license-free ISM band at 2.45  GHz. To
   avoid interfering with other protocols that use the 2.45 GHz band, the
   Bluetooth protocol divides the band into 79 channels (each 1 MHz wide)
   and changes channels up to 1600 times per second. Implementations with
   versions 1.1 and 1.2 reach speeds of 723.1  kbit/s. Version 2.0
   implementations feature Bluetooth Enhanced Data Rate (EDR) and reach
   2.1  Mbit/s. Technically, version 2.0 devices have a higher power
   consumption, but the three times faster rate reduces the transmission
   times, effectively reducing power consumption to half that of 1.x
   devices (assuming equal traffic load).

   Bluetooth differs from Wi-Fi in that the latter provides higher
   throughput and covers greater distances, but requires more expensive
   hardware and higher power consumption. They use the same frequency
   range, but employ different multiplexing schemes. While Bluetooth is a
   cable replacement for a variety of applications, Wi-Fi is a cable
   replacement only for local area network access. Bluetooth is often
   thought of as wireless USB, whereas Wi-Fi is wireless Ethernet, both
   operating at much lower bandwidth than the cable systems they are
   trying to replace. However, this analogy is not entirely accurate since
   any Bluetooth device can, in theory, host any other Bluetooth
   device—something that is not universal to USB devices.

   Many USB Bluetooth adapters are available, some of which also include
   an IrDA adapter. Older (pre-2003) Bluetooth adapters, however, have
   limited services, offering only the Bluetooth Enumerator and a
   less-powerful Bluetooth Radio incarnation. Such devices can link
   computers with Bluetooth, but they do not offer much in the way of
   services that modern adapters do.

Security

   Bluetooth implements authentication and key derivation with custom
   algorithms based on the SAFER+ block cipher. The initialization key and
   master key are generated with the E22 algorithm. The E0 stream cipher
   is used for encrypting packets. This makes eavesdropping on
   Bluetooth-enabled devices more difficult.

Social concerns

Security concerns

   2003:
   In November 2003, Ben and Adam Laurie from A.L. Digital Ltd. discovered
   that serious flaws in Bluetooth security may lead to disclosure of
   personal data. It should be noted, however, that the reported security
   problems concerned some 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 the problem to the world. A new attack called BlueBug was
   used for this experiment.

   2004:
   In April 2004, security consultant firm @stake (now Symantec) revealed
   a security flaw that makes it possible to crack 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 to spread itself among mobile phones appeared on the
   Symbian OS. The virus was first described by Kaspersky Lab and requires
   users to confirm the installation of unknown software before it can
   propagate.

   The virus was written as a 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 real) security threat to Bluetooth or Symbian
   OS since the virus has never spread in the wild.

   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 poses a
   potential security threat because it enables attackers to access
   vulnerable Bluetooth-devices from a distance beyond expectation.
   However, such experiments do not work with signal amplifiers. The
   attacker must also be able to receive information from the victim to
   set up a connection. No attack can be made against a Bluetooth device
   unless the attacker knows its Bluetooth address and which channels to
   transmit on.

   2005:
   In April 2005, Cambridge University security researchers published
   results of their actual implementation of passive attacks against the
   PIN-based pairing between commercial Bluetooth devices, confirming the
   attacks to be practicably fast and the Bluetooth symmetric key
   establishment method to be vulnerable. To rectify this vulnerability,
   they carried out an implementation which showed that stronger,
   asymmetric key establishment is feasible for certain classes of
   devices, such as handphones.

   In June 2005, Yaniv Shaked and Avishai Wool published the paper
   "Cracking the Bluetooth PIN1," which shows both passive and active
   methods for obtaining the PIN for a Bluetooth link. The passive attack
   allows a suitably equipped attacker to eavesdrop on communications and
   spoof if they were present at the time of initial pairing. The active
   method makes 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. After that, the first method can 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 the PIN during the
   attack when the device prompts them to. Also, this active attack
   probably requires custom hardware, since 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 are advising users to ensure that any mobile
   networking connections are de-activated if laptops and other devices
   are left in this way.

   2006:
   In April 2006, researchers from Secure Network and F-Secure published a
   report that warns of the large number of devices left in a visible
   state, and issued statistics on the spread of various Bluetooth
   services and the ease of spread of an eventual Bluetooth worm.

   In October 2006, at the Luxemburgish Hack.lu Security Conference, Kevin
   Finistere and Thierry Zoller demonstrated and released a remote root
   shell over Bluetooth on Mac OSX 10.3.9 and 10.4. They also demonstrated
   the first Bluetooth PIN and Linkkeys cracker, which is based on the
   research of Wool and Shaked.

Health concerns

   Bluetooth uses the microwave radio frequency spectrum in the 2.4 GHz to
   2.4835 GHz range. The fact that microwave ovens use the same frequency
   may account for some of the public concern about a possible health
   hazard. Maximum power output from a Bluetooth radio is 1mW, 2.5mW, and
   100mW for Class 3, Class 2, and Class 1 devices respectively, which
   puts Class 1 at roughly the same level as cell phones, and the other
   two classes much lower.. Accordingly, Class 2 and Class 3 Bluetooth
   devices are considered less of a potential hazard than cell phones, and
   Class 1 may be of concern comparable to that of cell phones.

Origin of the name and the logo

   Bluetooth was named after a late 900s king, Harald Bluetooth King of
   Denmark and Norway. He is known for his unification of previously
   warring tribes from Denmark (including Scania, present-day Sweden,
   where the Bluetooth technology was invented), and Norway. Bluetooth
   likewise was intended to unify different technologies, such as
   computers and mobile phones.

   The name may have been inspired less by the historical Harald than the
   loose interpretation of him in The Long Ships by Frans Gunnar
   Bengtsson, a Swedish Viking-inspired novel.

   The Bluetooth logo merges the Nordic runes analogous to the modern
   Latin H and B: ( haglaz) and ( berkanan) forming a bind rune.

Bluetooth Consortium

   In 1998, Ericsson, IBM, Intel, and Nokia, formed a consortium and
   adopted the code name Bluetooth for their proposed open specification.
   In December 1999, 3Com, Lucent Technologies, Microsoft, and Motorola
   joined the initial founders as the promoter group. Since that time,
   Lucent Technologies transferred their membership to their spinoff Agere
   Systems, and 3Com has left the promoter group.

   Retrieved from " http://en.wikipedia.org/wiki/Bluetooth"
   This reference article is mainly selected from the English Wikipedia
   with only minor checks and changes (see www.wikipedia.org for details
   of authors and sources) and is available under the GNU Free
   Documentation License. See also our Disclaimer.
