bluetooth technology by volkan sevindik

03-06-2007VOLKAN SEVINDIK

OUTLINE

• What is Bluetooth?

• Fundemantals of Bluetooth Technology

• Bluetooth Security

• Bluetooth in the Marketplace

• Future Directions

• Bluetooth is an open standard specification for a radio frequency (RF)- based, short range connectivity technology.

• It is designed to be an inexpensive, wireless networking system for all classes of portable devices, such as laptops, PDAs (personal digital assistants), and mobile phones.

• The idea of a cable-free, or wireless, technology was initially concieved by Ericsson in1994, when the company began a study to investigate the feasibility of a low-power, low-cost radio interface between mobile phones and their accessories .

What is Bluetooth?

What is Bluetooth?

• The original idea was to create small, inexpensive radio chip that could be used in mobile computers, printers, mobile phones, and so on, to transmit data between these devices.

• The projected cost of the chip was around $5, and it was to require low power so that it could be used in devices that rely on battery life.

• As the idea grew, a special interest special interest group (SIG)group (SIG) was formed to create a standard for this technology (1998).

What is Bluetooth?

• The original SIG (Special Interest Group) consisted of five companies.These were Ericsson, IBM, Intel, Nokia, Toshiba.

What is Bluetooth?

• The name Bluetooth comes from Danish history. Harald Harald BlatandBlatand, who was called Bluetooth, became king and he was skilled Viking warrior. When his sister asked for help to secure control in Norway after her husband died, Harald quickly seized the opportunity to unite the countries and expand his kingdom.

• Bluetooth name is the English version of the original Viking word, Blatand. The Bluetooth name was chosen for the wireless technology because its developers and promoters hope it will unite the mobile world, just as King Harald united his world.

What is Bluetooth?

• The bluetooth specification does not define a totally new technology.

• In fact, Bletooth heavily depends on existing radio communications and networking technologies, which enables it to be operationally compatible with the existing devices that also use these technologies.

• Many of the various terms and concepts used in Bluetooth are borrowed from other areas and included in the specification of Bluetooth’s elements.

• However, what makes Bluetooth unique is how it applies its proprietary components and the existing technologies to define its central core operations and its application profiles.

• A complete Bluetooth system will require four elemets:

1- An RF portion for receiving and transmitting data

2- A module with a baseband microprocessor

3- Memory

4- An interface to the host device (such as mobile phone)

Fundamentals of Bluetooth Technology


• The building block of Bluetooth technology is the Bluetooth stack, which includes the hardware and software partions of the system.


• The Bluetooth stack has the following components:

RF portion for reception and transmission

Link control unit

Link manager to support lower-layer protocols

Interface to the host device

L2CAP to support upper-layer protocols

Bluetooth applications


• The radio frequencyradio frequency portion provides the digital signal processing component of the system, and the baseband processes these signals.

Data or Voice


• The link controllerlink controller handles all the baseband functions and supports the link manager.It sends and receives data, identifies the sending device, performs authentication, and determines the type of frame to use for sending transmissions. The link controller also directs how devices listen for transmissions from other devices and can move devices into power saving modes.

Send and receive data Identify the device Authentication

???SlaveMaster101010..


• The link managerlink manager, located on top of the link controller, controls setup, authentication, link configuration, and other low-level protocols. Together, the basebandbaseband and the link managerlink manager establish connections for the network.

AuthenticationLink physical parameter control

Link configuration

Encryption controlMaster-to-slave changing

(vice versa)

Fundamentals of Bluetooth Technology• The host controller interface (HCI) communicates the lower-layer protocols to the host

device (mobile computer or mobile phone). The HCI is driven from the host, with command being sent to the host controller. The host controller may send events to the host.

Link control

Link policy

Informational parameters

TestingStatus parameters


• The purpose of Logical Link Control and Adaptation Layer Protocol (L2CAP) is to provide connection-oriented and connectionless data services to higher layer protocols. The upper layer protocols consist of service-specific applications that must be integrated into the host application.

Multiplexing of higher layer protocols

Establishment, maintenance and clearing of logical connections for connection-oriented services

Segmentation and re-assembly services to allow packets up to 64 kilobytes to be transported between L2CAP entities.


• Another element in the Bluetooth stack that relates to radio communications is the RFCOMM protocolRFCOMM protocol, which allows for the emulation of serial ports over the L2CAP.

• The Service Discovery Protocol (SDP)Service Discovery Protocol (SDP) provides the means for Bluetooth applications to discover the services and the characteristics of the available services that are unique to Bluetooth.

• The Bluetooth Device ManagerDevice Manager provides for device inquiry and connection management services.


• In Bluetooth technology, links and channels are used to transmit data between Bluetooth units. First, the links are established.

• Bluetooth technology supports two link types:

1- Synchronous connection-oriented (SCO)

2- Asynchronous connectionless (ACL)

• The SCO links are used primarily for voice communications.

• The ACL links are used for packet data. Bluetooth devices can use one of these link types and can change link types during transmissions, although an ACL link must be established before an SCO link can be used.


• Bluetooth uses five logical channels to transfer different types of information between devices:

1- Link control (LC) manages the flow of packets over the link interface.

2- Link manager (LM) transports link management information between participating stations.

3- User asynchronous (UA) carries user data

4- User isochronous (UI) carries user data.

5- User synchronous (US) carries synchronous (SCO) data.


• Bluetooth protocols are sets of conventions that govern the transmittal of data in upper and lower layers of the system. The lower-layer protocols pertain to establishing connections, and the upper layers correspond to specific types of applications.

• Link Control Protocol Link Control Protocol is responsible for delivery of the basic data elements. All packet information is transmitted in a specific time-slot format (a single time slot in the Bluetooth system lasts 625 μs).


• Bluetooth operates as a 79 channel frequency-hopping system is the frequency range 2.4-2.4835 GHz with a channel spacing of 1Mhz. The hopping rate is 1600 hops/sn, and the hopping sequence, which is different for each piconet, is a function of both the master’s Bluetooth device address and its Bluetooth clock.

• The Link Manager Protocol (LMP)Link Manager Protocol (LMP) is a command-response system for transmitting data. It transports packet through the Bluetooth baseband link protocol, which is a time-slot-oriented mechanism. LMP packets are limited in size to ensure that they fit into a single time slot.

Fundamentals of Bluetooth Technology- Communication and Networking

• A Bluetooth transciever is a frequency-hopping spread-spectrum (FHSS) device that uses the unlicensed (worldwide) 2.4GHz ISM (Industrial, Scieintific, Medical) frequency band.

• In most countries there are 79 channels available; however some countries use only 23 channels. The nominal bandwidth for each channel 1MHz.

• FCC Part 15.247 regulations restrict the maximum allowed peak power output to 1 watt and require that at least 75 of the 79 channels be used in a pseudo-random manner.

• A device cannot operate on a given channel for longer than 0.4 sec within any 30 sec period in order to minimize the amount of interference (802.11 b/g, HomeRF, microwave ovens).


• There classes of Bluetooth device have been defined, the maximum transmitter powers being 100mW (20dBm), 2.5mW (4dBm), and 1mW (0dBm) for class 1,2, and 3 devices. The nominal power of a class 3 device is 1mW (0dBm). The nominal value provides some indication of teh expected performance, whereas the maximum vaşue is allowe only test sepecification.

• The receive sensitivity is about –70dBm. This corresponds to the receiver power at 10m from a 0dBm transmitter, the carrier-to-interference ratio being 21dBm at this point and the interferer being the assumed noise within the receiver.


• Although the concept of cable replacement might create a vision of point-to-point communication, the Bluetooth SIG has exploited the fact that wireless devices can communicate with other devices that are within the range.

• A network of communicating Bluetooth devices is referred to as a piconet. The topology of a piconet is a star configuration.


• A piconetpiconet has a single master unit and one or more slave units (up to seven). The relationship among units is characterized by source and destination transmissions. That is, the unit sending data (initiating connection) is known as the source (master unit). The unit receiving the transmission is known as the destination (slave) unit.

• The terms mastermaster and slaveslave refer only to the protocol on a given channel; the Bluetooth units themselves are identical and can become masters or slaves in any piconet, depending on which unit initiates the transmission.

• MasterMaster of a specific piconet can be changed dynamically during the existence of that piconet.


• Several piconets may be combined to form a scatternet.

Although all devices are capable of acting both as a master and slave, they can not be a master and a slave exactly the same time. They have to switch between modes.


• Within a piconet, there can be up to seven active slaves. This is a restriction of the air interface, which uses a three-bit field to identify the active member.

• The Bluetooth standart provides mechanisms for Bluetooth devices to discover each other, exchange identities and establish communications with each other, all without prior knowledge of each other. This is referred to as ad hoc networking. An example of its application is where a number of people are around a conference table; information can be shared and presentation material can excahnged in a very simple way.


• A Bluetooth device can be in one of the following states: Standby, Inquiry, Page, Connected, Transmit, Hold, Park, or Sniff.


• A device is powered on but has not yet joined a piconet.

• It enters the inquiry state when it sends out requests to find others devices to which it might connect

• Sending messages looking for devices to which it can invite to join its piconet (master).

• When successful communication is made between the master and the new device (slave), the new device enters this state.

• During the transmission, the slave is in Transmit state.

• Low-power mode. Slave sleeps for a pre-determined # of time slots

• When slave has no data to send or receive, it enters Park state.

Bluetooth Security

• To provide privacy, a number of security features are supported.

Encryption Against eavesdropping

Authentication Verification of identity

• By exchanging (private) kcys, trusted relationships may be established between devices. For example, a headset can be ‘paired’ with a mobile phone by entering into each device a PIN (personal identification number), from which a (private) key is then derived for use in authentication.

Bluetooth Security

• Subsequently the headset needs only to be authenticated to verify its identity-the PIN does not need to be entered each time the user wishes to use the headset with the phone.

• Over the-air encryption is included within the Bluetooth specification the encryption key being derived from the private keys used during the authentication process. The encryption key length is negotiated between master and slave for a particular session It can be cons,dered to have a default value of 64 bits, which can be increased up to 128 bits.

• This is seen as a future proofing of the basic algorithms to allow upgrading to greater security by the use of longer keys. It also permits the use of a shorter key where local regulations so demand.

Bluetooth in Market Place

Bluetooth is only one of several technologies that support wireless communications. Other can complement the Bluetooth environment, potentially coexisting and working well together.

Bluetooth in Market Place Comparison with Infrared

• Although infrared and Bluetooth technologies support many of the same applications, each technology has its advantages and disadvantages.

• In terms of data transfer, infrared does provide a faster data rate than Bluetooth, which is a big advantage. Bluetooth moves data between devices at about 721kbps, while infrared transmits data at a rate of 4 Mbps.

Bluetooth in Market Place Comparison with Infrared

• However, Bluetooth does not require line-of-sight for communication with other devices, and this makes easy

communication with other devices in a piconet.

• Exchanging data with multiple devices is not possible with infrared. It only offers point-to-point links between devices.

Bluetooth in Market Place Comparison with HomeRF

• Home Radio Frequency (HomeRF) is another wireless technology that uses the unlicensed 2.4 GHz ISM (Industrial, Scientific, Medical) band. It supports both voice and data transmission using frequency hopping spread spectrum technique.

• HomeRF transmission rates are from 2 to 10 Mbps.

• This technology is not intended for portable devices or ad hoc connections, giving Bluetooth a clear advantage in thşs area.

Bluetooth in Market Place Comparison with HomeRF

• HomeRF and Bluetooth technologies can easily coexist and in some cases complement each other. For example, to create a viable home network, you could use HomeRF to connect all PCs to each other, and with Bluetooth connections between peripherals and the PCs

Bluetooth in Market Place Comparison with WLAN

• Anaother wireless connection opition is the IEEE 802.11 standard, or Wireless Fidelity, as it is also known.

• Like Bluetooth, this technology uses RF signals broadcast in the 2.4GHz frequency band. This technology is strictly for data transmissions and does not handle voice signals. It can be used for ad hoc connections, but it basically replicates an Etherhet network without wires.

Bluetooth in Market Place Comparison with WLAN

• But, 802.11 technology does not work well as well as Bluetooth for ad hoc networking, because it requires somewhat complex

setup.

• Ad hoc networking is one of the strength of the Bluetooth environment. For this reason, the two technologies could coexist and augment each other, with users selecting Bluetooth for connecting peripherals to a PC and 802.11 for connecting the PC to the office LAN.

Future Directions

• The first Bluetooth products on the market are likely to be basic cable replacements.

• After the Bletooth chips attain critical market mass, new markets will open up for Bletooth technology.

• Software development kits (SDKs) are available for Bluetooth developers. More competition in the SDK area and lower prices on Bşuetooth chips will promote more development among manufacturers.

• The contiuning development and refinement of the Bluetooth specifications will ensure product interoperability regardless of product design and manufacturer.

• New market opportunities will open up for Bluetooth as well as 3G products to extend the reach of cellular systems well beyond current boundaries.

References

1- S. Sairam, N. Gunesakaran and S.Rama Reddy, "Bluetooth in Wireless Communication", IEEE Comm., pp. 90-96, June 2002.

2- P. McDermott-Wells, "Bluetooth Technology", IEEE Comm., December 2004.

3- W. Lilakiatsakun, A. Seneverine, " Wireless Home Networks based on a Hierarchical Bluetooth Scatternet Architecture", IEEE Comm., pp. 1531-2261, 2001.

4- R.Shepherd, "Bluetooth Wireless Technology in the Home", Electronics&Communication Engineering Journal, October 2001.

5- http://www.bluetooth.org6- http:// www.bluetooth.com7- http:// www.homerf.org8- http:// www.irda.org9- http:// www.ti.com

bluetooth technology by volkan sevindik

Documents

bluetooth specification

bluetooth stack

complete bluetooth system

wireless technology

new technology

host device mobile computer

mobile phones

upper layer protocols