Bluetooth Paper Presentation

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Bluetooth Technology

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A New Era of Connectivity
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ABSTRACT
ogtransfer technologies such as IrDA and

Home RF. It illustrates how a
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The seemingly endless

entanglement of data wires connecting
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today’s electronic devices has become

slightly less jumbled with the
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introduction of Bluetooth technology
connection is made in Bluetooth
and the creation of a wireless data link.
between two environments. It mainly
This article delves into the
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emphasizes the architecture of
implementation and architecture of
Bluetooth. It gives over all Bluetooth
Bluetooth. It also describes the
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packet structure and different
functional overview and applications of
communication and data information
Bluetooth. It gives significant
protocols such as WAP, UDP, IP,TCP
advantages of Bluetooth over other data



,RFCOMM, L2CAP etc. It also operating electronic devices. These

explains Link Security by Data details in the article establish the

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Encryption. Finally it narrates how growing need for Bluetooth technology.

Bluetooth will bring a new level of

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connectivity and convenience when

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INTRODUCTION Blaatand"Bluetooth"2nd,king of
Bluetooth is a method for data Denmark.
communication that uses short-range radio
WHY BLUETOOTH?
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links to replace cables between
computers and their connected units. Bluetooth attempts to provide significant
Bluetooth is a radio frequency advantages over other data transfer
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technology utilizing the unlicensed technologies such as IrDA and HomeRF.
2.5GHz industrial, scientific and medical IrDA is already popular in PC to
(ISM) band. Bluetooth is an open standard peripherals,but is severely limited by the
for wireless connectivity with supporters
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short connection distance of 1m and the
mostly from the PC and cell phone
line of sight requirement for
industries. Not surprisingly, its primary
communication. Due to its RF nature
market is for data and voice transfer
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bluetooth is not subjected to such
between communication devices and PCs.
limitations. In addition to wireless
Bluetooth was invented by L.M.Ericson
device connections up to 10-100m,
of Sweden in 1994. The standard is
devices need not be within line of sight.
named after Harald



Also it is designed to be low cost i.e packet) to search and locate these
devices.
under $10/unit. • The existing Bluetooth devices already

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within the area (and usually unware of
Establishing a connection in any inquiring devices) will occasionally
enter an inquiry scan state of their own
Bluetooth:
to troll for any inquiring devices.
• When a device in the inquiry scan state
Linking one Bluetoooth device to another to
receives an inquiry packet, it will

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another involves a series of inquiry and
respond with a frequency hop
paging procedures. The inquiry process
synchronization (FHS) packet that is
entails the following steps:
sent back to the inquiring device.
• The Bluetooth device sends out an

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inquiry access code packet (inquiry

Once the inquiry routine is completed, the • While the paging device (the master) is
paging process follows:
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paging, the target (slave) device may be
• The inquiring Bluetooth device now involved in other piconets.
wants to establish a connection with Occasionally, it will enter the page scan
another Bluetoooth device. state and listen for pages directed to it,
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• To successfully locate and page a target scanning through 16 different
Bluetooth device, the paging device frequencies. When it receives a page
estimates the hop frequency and clock from the paging device, it will respond
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of the target Bluetooth device using the to the page by sending an update of its
FHS packet received during inquiry. clock to the paging device.
• The paging device “pages” the target • Once the paging device receives a page
device with the target device’s device response from the target device,
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access code (DAC). The paging device information vital for a connection is
transmits the DAC on several different exchanged between the two devices.
hop frequencies that it thinks the target Information exchanged includes the
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device is receiving (as calculated using device address and clock of the paging
the FHS packet) and continues to do so device, which is used to determine the
until a connection is made. timing and frequency-hop sequence of
the newly formed piconet. When all



connection information has been broken down into smaller packets and sent
communicated, the connection is serially with the least significant bit sent

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complete, and the two devices can begin first. Each data packet (represented in Figure
to exchange data with one another. 2) contains three fields: an access code, a
header, and a payload.

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Bluetooth packet format:

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Since Bluetooth is meant to be compatible
with many different applications, it must be
able to send data with different protocols
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quickly and efficiently. When data is
transmitted at the lowest level, it is first
Access codes
At the beginning of each Bluetooth packet is The packet header, which follows the access
an access code. The access code is used code and contains link control information,
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primarily for piconet identification and co9ntain six fields: AM_ADDR, TYPE,
synchronization. The access code identifies FLOW, ARON, SEQN, and HEC (Figure 4).
the piconet to which each data packet • AM_ADDR, a 3-b active member
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belong; all data packets having both a packet address, is used to indicate where the
header and payload present will have a 72-b packet is destined. When a slave
access code; otherwise, the access code is receives a data packet, it checks the
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68-b long. Access codes are also used packet header’s AM_ADDR. If it
extensively in Bluetooth with no header or matches its own assigned AM_ADDR,
payload present. The access code itself the packet will be decoded; otherwise, it
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(Figure 3) is divided into three sections- is discarded.
preamble, sync word, and trailer-which are • The 4-b TYPE field indicates the type of
not present in inquiry or device access packet that has been sent. There are up
codes. to 16 different types of Bluetooth
Packet header packets.



• The FLOW bit is used for flow control. one-third the forward error correction
For example, if the receive (RX) buffer (FEC) rate, extends the total bit length

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of a recipient device is full, it will to 54 b.
indicate in its response to the master that • The payload , which follows the header,
it cannot accept any data at that can range from 0 to 2,745 b, and
moment. Once it can receive more data, contains the actual data of interest. With

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the FLOW bit is changed from 0 to 1. a packet capable of being sent during
• ARQN is the acknowledge bit that every 625 micro second time slot, a
informs the source whether the previous maximum bit rate of 723.2 kb/s can be

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transaction was successful. achieved for an ACL, and 64 kb/s can be
• The sequence (SEQN) bit allows the achieved for an ACL, and 64 kb/s for an
source and the recipient to keep track of SCO.
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the packets that have been sent. The bit Bluetooth can handle the transmission of
is inverted on each packet transmission many different applications. This entails
and used to prevent the reception of dealing with different architectural layers to
packets that may have been sent twice. decompose the application data into a form
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Repeat transmission of a packet occurs suitable for transmission over a Bluetooth
when the acknowledgement signal of a link, as well as to reassemble the data into
successful data transaction to the master its original form at the receiving end.
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fails to transmit. The receiving device
can simply compare the SEQN bit of the GENERAL BLUETOOTH
packet that was previously processed to ARCHITECHTURE
determine whether to discard or accept Facilitating this data transmission is a series
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the packet. of protocols within the Bluetooth system
• The header error check, HEC, is used to that processes the data for suitable
check the integrity and accuracy of the transmission and receipt.
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header during each packet transaction. If The general structure of a Bluetooth
the HEC is incorrect, the packet is system consists of a microprocessor that
discard. While the header comprises 18 handles all the baseband specifications, and
b, the fact that it is encoded at a rate of several software layers that structure the



data so that it may be sent properly over a into Bluetooth data packets and
Bluetooth link. Figure 5 provides a good subsequently sent over a Bluetooth link.

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representation of the architecture. Below RFCOMM lies the logical link
At the highest architecture level lies the control and adaptation protocol (L2CAP)
different communication and data that further supports the adaptation of other
information protocols that can communicate communication protocols, such as telephony

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over the Bluetooth link, including wireless control specification binary (TCS-binary)
application protocol (WAP), user datagram and the Bluetooth-established service
protocol (UDP), transport control protocol discovery protocol (SDP), as well as

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(TCP), internet protocol (IP), and point-to- performing the multiplexing between all
point protocol (PPP). While all of these are incoming upper-level protocols (RFCOMM,
standalone communication protocols, they TCS, SDP), as well as performing the
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can be adapted for transmission over a multiplexing between all incoming upper-
Bluetooth link. To support these different level protocols (RFCOMM, TCS, SDP). In
types of communication protocols, the addition to protocol multiplexing, L2CAP is
Bluetooth system architecture must be responsible for the segmentation of outgoing
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capable of capable of differentiating and data packets so they may be transferred to
converting data associated with these the baseband processor cannot handle data
protocols into data packets that the packets of great size. L2CAP is also
Bluetooth baseband controller and RF responsible for the reassembly of received
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transceiver can send. data packets, which are subsequently sent to
One of the protocols within the Bluetooth one of the higher-level protocols designated
architecture that is responsible for this to receive this data.
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adaptation is RFCOMM, which emulates a Once the original data has been
serial port and can be used by applications segmented by L2CAP into subsequent
that use the serial ports on a Bluetooth L2CAP packets, the packets are then sent to
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device. RFCOMM can take the data from the host controller interface (HCI), which is
some of the higher level protocols responsible for sending data to and receiving
mentioned previously and adapt it so it can data from the lower level Bluetooth
be sent down to the baseband and converted hardware (baseband controller) through a
physical bus (USB, RS232, PCI), HCI



further alters the L2CAP packets so that the
data may be transported over one of the

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physical buses. This data is received by the
link manager and baseband controller that
assemble it into packets that are
communicable using a Bluetooth link.

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At the lowest level lie the link manager
and baseband controller. The baseband
controller performs all low level processing,

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such as Bluetooth packet composition for
transmission and packet decomposition upon
reception. Running on the baseband
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controller is firmware implementing the link
LINK SECURITY
manager protocol, which handles link As with any communication link, there must
control, is responsible for placing the device be security surrounding the data transfer
in low power states, and performs any between two devices. With the frequency
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encryption of the data transmitted. hopping and the timing involved in the
hopping, is very difficult for an external
device to eavesdrop on a Bluetooth link.
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However, there are some security risks from
other Bluetooth devices already
synchronized to an existing piconet and
accessing sensitive information intended for
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another device on the piconet.
Data encryption is used to prevent
other devices and the piconet from
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eavesdropping on data transactions. The
basic security procedure used over a
Bluetooth link is based on a challenge
response scheme. The authenticity of a



Bluetooth device is determined a challenge capability combined with adhoc device
sent by a verifier to a claimant and response connection and automatic service

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to that challenge by that claimant device. discovery make it a superior solution for
The response to the challenge is a function
mobile devices and Internet applications.
of the challenge, the claimant device’s
Bluetooth finds applications in PC and
Bluetooth address, and a secret key. The
peripheral networking , hidden

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secret key is known only by the verifier and
computing ,data synchronization for
the true claimant device and is not known to
any other Bluetooth device. If the claimant
address books and calendars, home

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contains the correct secret key, the correct networking and home appliances such a
response to the challenge will be calculated, s heating systems and entertainment
and information between the verifier and devices. Asynchronous data channel and
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claimant can begin, otherwise verifier will up to three synchronous voice channels,
detach from the claimant device. or one channel for both voice and data.
This capability combined with adhoc
ADVANTAGES AND APPLICATIONS OF
BLUETOOTH device connection and automatic service
Bluetooth can handle data and voice
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discovery make it a superior solution for
simultaneously. It is capable of
mobile devices and Internet applications.
supporting one between computers and
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their connected units. Bluetooth is an
LIMITATIONS OF BLUETOOTH
open standard for wireless connectivity
with supporters mostly from the PC and
The main drawback of Bluetooth is its
cell phone industries. Its primary market
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limited connection distance and less
is for data and voice transfer between transmission speeds. It supports data rates
communication devices and PCs. It is up to 780kb/s which may be used for
capable of supporting one asynchronous
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unidirectional data transfer. It is perfectly
data channel and up to three adequate for file transfer and printing
synchronous voice channels, or one applications.
channel for both voice and data. This



CONCLUSION 3. “Bluetooth” IEEE Microwave
Magazine September 2002.

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With its relatively low implementation costs,
Bluetooth technology seems destined to
dominate the electronic landscape, as
humans worldwide will be able to form

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personal area networks with devices and
completely simplify the way in which
they interact with electronic tools and

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each other.
In the years to come, Bluetooth will
become a worldwide connectivity among
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electronic devices, leading to
applications unthinkable by today’s
technological standards. Because the
radio frequency used is globally
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available, Bluetooth can offer fast and
secure connectivity all over the world.
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REFERENCES:

1. J.C. Haartsen et al. ,”The
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Bluetooth Radio System” IEEE
pers. Commum.,Feb.2000 .
2. “Bluetooth in Wireless
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Communications” IEEE
Communications Magazine June
2002


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