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BLUETOOTH SYSTEM

ADITI BHAUMICK 

ROLL NO.: ECE 57

UNIVERSITY ROLL NO.: 071040103053

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CONTENTS:

INTRODUCTION

3

OPERATION

3

HISTORY 

4

RF MODULE 5

RS232C SERIAL COMMUNICATION 5

BLUETOOTH PROTOCOLS

6

DIFFERENT BLUETOOTH NETWORKS 9

CONCLUSION 10

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BIBLIOGRAPHY 11

  INTRODUCTION

BLUE TOOTH SYSTEM

CONCEPT OF BLUETOOTH:

Bluetooth is an open wireless technology standard for exchanging dataover short distances (using short wavelength radio transmissions) from fixed

and mobile devices, creating Personal Area Networks (PANs) with highlevels of security. Bluetooth is essentially a networking standard that worksat two levels:

• It provides agreement at the physical level -- Bluetooth is a radio-frequency standard.

• It provides agreement at the protocol level, where products have to agreeon when bits are sent, how many will be sent at a time, and how the partiesin a conversation can be sure that the message received is the same as themessage sent.

  OPERATION :

How Bluetooth Operates :

Bluetooth networking transmits data via low-power radio waves. Itcommunicates on a frequency of 2.45 gigahertz (actually between 2.402GHz and 2.480 GHz, to be exact). This frequency band has been set aside byinternational agreement for the use of industrial, scientific and medicaldevices (ISM).

A number of devices that you may already use take advantage of this sameradio-frequency band. Baby monitors, garage-door openers and the newestgeneration of cordless phones all make use of frequencies in the ISM band.

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Making sure that Bluetooth and these other devices don't interfere with oneanother has been a crucial part of the design process.

One of the ways Bluetooth devices avoid interfering with other systems is bysending out very weak signals of about 1 milliwatt. By comparison, the

most powerful cell phones can transmit a signal of 3 watts. The low powerlimits the range of a Bluetooth device to about 10 meters (32 feet), cuttingthe chances of interference between your computer system and yourportable telephone or television. Even with the low power, Bluetooth doesn'trequire line of sight between communicating devices. The walls in yourhouse won't stop a Bluetooth signal, making the standard useful forcontrolling several devices in different rooms.

Bluetooth can connect up to eight devices simultaneously. With all of thosedevices in the same 10-meter (32-foot) radius, you might think they'dinterfere with one another, but it's unlikely. Bluetooth uses a technique

called spread-spectrum frequency hopping that makes it rare for morethan one device to be transmitting on the same frequency at the same time.In this technique, a device will use 79 individual, randomly chosenfrequencies within a designated range, changing from one to another on aregular basis. In the case of Bluetooth, the transmitters change frequencies1,600 times every second, meaning that more devices can make full use of alimited slice of the radio spectrum. Since every Bluetooth transmitter usesspread-spectrum transmitting automatically, it’s unlikely that twotransmitters will be on the same frequency at the same time. This sametechnique minimizes the risk that portable phones or baby monitors willdisrupt Bluetooth devices, since any interference on a particular frequency

will last only a tiny fraction of a second.When Bluetooth-capable devices come within range of one another, anelectronic conversation takes place to determine whether they have data toshare or whether one needs to control the other. The user doesn't have topress a button or give a command -- the electronic conversation happensautomatically. Once the conversation has occurred, the devices -- whetherthey're part of a computer system or a stereo -- form a network. Bluetoothsystems create a personal-area network (PAN), or piconet, that may fill aroom or may encompass no more distance than that between the cell phoneon a belt-clip and the headset on your head. Once a piconet is established,the members randomly hop frequencies in unison so they stay in touch with

one another and avoid other piconets that may be operating in the sameroom.

A master Bluetooth device can communicate with up to seven devices in a

piconet (An ad-hoc computer network using Bluetooth technology). The

devices can switch roles, by agreement, and the slave can become the

master at any time.

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At any given time, data can be transferred between the master and

one other device (except for the little-used broadcast mode). The master

chooses which slave device to address; typically, it switches rapidly from one

device to another in a round-robin fashion.

 The Bluetooth Core Specification provides for the connection of two or

more piconets to form a scatternet, in which certain devices serve as

bridges, simultaneously playing the master role in one piconet and the slave

role in another.

History :

Harald Bluetooth was king of Denmark in the late 900s. He managed to uniteDenmark and part of Norway into a single kingdom then introducedChristianity into Denmark. He left a large monument, the Jelling rune stone,

in memory of his parents. He was killed in 986 during a battle with his son,Svend Forkbeard. Choosing this name for the standard indicates howimportant companies from the Nordic region (nations including Denmark,Sweden, Norway and Finland) are to the communications industry

 The Bluetooth specification was developed in 1994 by Jaap Haartsen andSven Mattisson, who were working for Ericsson in Lund, Sweden.[23] Thespecification is based on frequency-hopping spread spectrum technology.

 The specifications were formalized by the Bluetooth Special Interest Group (SIG). The SIG was formally announced on May 20, 1998. Today it has amembership of over 13,000 companies worldwide. It was established by

Ericsson, IBM, Intel, Toshiba and Nokia, and later joined by many othercompanies

RF MODULE:

Bluetooth uses a radio technology called frequency-hopping spread

spectrum, which chops up the data being sent and transmits chunks of it on

up to 79 bands (1 MHz each; centered from 2402 to 2480 MHz) in the range

2,400-2,483.5 MHz (allowing for guard bands). This range is in the globally

unlicensed Industrial, Scientific and Medical (ISM) 2.4 GHz short-range radio

frequency band.

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RS232 C SERIAL COMMUNICATION:

Figure: RS232 Data Interface

In computing, a serial port is a serial communication physical interface

through which information transfers in or out one bit at a time (contrast

parallel port). Throughout most of the history of personal computers, data

transfer through serial ports connected the computer to devices such asterminals and various peripherals.

While such interfaces as Ethernet, FireWire and USB all send data as a

serial stream, the term ‘serial port’ usually identifies hardware more or less

compliant to the RS-232 standard, intended to interface with a modem or

with a similar communication device.

Modern computers without serial ports may require serial-to-USB

converters to allow compatibility with RS 232 serial devices. Serial ports are

still used in applications such as industrial automation systems, scientific

instruments, shop till systems and some industrial and consumer products.

Server computers may use a serial port as a control console for diagnostics.

Network equipment (such as routers and switches) often use serial console

for configuration. Serial ports are still used in these areas as they are simple,

cheap and their console functions are highly standardized and widespread. A

serial port requires very little supporting software from the host system.

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BLUE TOOTH PROTOCOLS:

Bluetooth is defined as a layer protocol architecture consisting of core

protocols, cable replacement protocols, telephony control protocols, and

adopted protocols.

Mandatory protocols for all Bluetooth stacks are: LMP, L2CAP and SDP.

Additionally, these protocols are almost universally supported: HCI and

RFCOMM.

LMP (Link Management Protocol): Used for control of the radio linkbetween two devices. It is implemented on the controller.

L2CAP (Logical Link Control & Adaptation Protocol): Used to multiplex

multiple logical connections between two devices using different higher level

protocols. It provides segmentation and reassembly of on-air packets.

In Basic mode, L2CAP provides packets with a payload configurable up

to 64kB, with 672 bytes as the default MTU and 48 bytes as the minimum

mandatory supported MTU.

In Retransmission & Flow Control modes, L2CAP can be configured for

reliable or isochronous data per channel by performing retransmissions and

CRC checks.

Bluetooth Core Specification Addendum 1 adds two additional L2CAP modes

to the core specification. These modes effectively deprecate original

Retransmission and Flow

Control Modes:

Enhanced Retransmission Mode (ERTM): This mode is an improvedversion of the original retransmission mode. This mode provides a reliable

L2CAP channel.

Streaming Mode (SM): This is a very simple mode, with no retransmission

or flow control. This mode provides an unreliable L2CAP channel.

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Reliability in any of these modes is optionally and/or additionally

guaranteed by the lower layer Bluetooth BDR/EDR air interface by

configuring the number of retransmissions and flush timeout (time after

which the radio will flush packets). In-order sequencing is guaranteed by the

lower layer.

Only L2CAP channels configured in ERTM or SM may be operated over

AMP logical links.

SDP (Service Discovery Protocol): It allows a device to discover services

supported by other devices, and their associated parameters. For example,

when connecting a mobile phone to a Bluetooth headset, SDP will be used

for determining which Bluetooth profiles are supported by the headset

(Headset Profile, Hands Free Profile, Advanced Audio Distribution Profile

(A2DP) etc.) and the protocol multiplexer settings needed to connect to eachof them. Each service is identified by a Universally Unique Identifier (UUID),

with official services (Bluetooth profiles) assigned a short form UUID (16 bits

rather than the full 128).

HCI (Host/Controller Interface): Standardized communication between

the host stack (e.g., a PC or mobile phone OS) and the controller (the

Bluetooth IC). This standard allows the host stack or controller IC to be

swapped with minimal adaptation.

 There are several HCI transport layer standards, each using a differenthardware interface to transfer the same command, event and data packets.

 The most commonly used are USB (in PCs) and UART (in mobile phones and

PDAs).

In Bluetooth devices with simple functionality (e.g., headsets) the host

stack and controller can be implemented on the same microprocessor. In this

case the HCI is optional, although often implemented as an internal software

interface.

RFCOMM (Serial Port Emulation): Radio frequency communications

(RFCOMM) is a cable replacement protocol used to create a virtual serial data

stream. RFCOMM provides for binary data transport and emulates EIA-232 

(formerly RS-232) control signals over the Bluetooth base band layer.

RFCOMM provides a simple reliable data stream to the user, similar to

 TCP. It is used directly by many telephony related profiles as a carrier for AT

commands, as well as being a transport layer for OBEX over Bluetooth.

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Many Bluetooth applications use RFCOMM because of its widespread

support and publicly available API on most operating systems. Additionally,

applications that used a serial port to communicate can be quickly ported to

use RFCOMM.

BNEP (Bluetooth Network Encapsulation Protocol): BNEP is used for

transferring another protocol stack's data via an L2CAP channel. Its main

purpose is the transmission of IP packets in the Personal Area Networking

Profile. BNEP performs a similar function to SNAP in Wireless LAN.

AVCTP (Audio/Video Control Transport Protocol: Used by the remote

control profile to transfer AV/C commands over an L2CAP channel. The music

control buttons on a stereo headset use this protocol to control the music

player.

AVDTP (Audio/Video Distribution Transport Protocol): Used by the

advanced audio distribution profile to stream music to stereo headsets over

an L2CAP channel. It is intended to be used by video distribution profile in

the bluetooth transmission.

Telephony control protocol:  Telephony control protocol-binary (TCS BIN)

is the bit-oriented protocol that defines the call control signaling for the

establishment of voice and data calls between Bluetooth devices.

Additionally, TCS BIN defines mobility management procedures for handling

groups of Bluetooth TCS devices.

 TCS-BIN is only used by the cordless telephony profile, which failed to

attract implementers. As such it is only of historical interest.

Adopted protocols: Adopted protocols are defined by other standards-

making organizations and incorporated into Bluetooth’s protocol stack,

allowing Bluetooth to create protocols only when necessary. The adopted

protocols include:

Point-to-Point Protocol (PPP): Internet standard protocol for transporting

IP datagrams over a point-to-point link.

TCP/IP/UDP: Foundation Protocols for TCP/IP protocol suite.

Object Exchange Protocol (OBEX): Session-layer protocol for the

exchange of objects, providing a model for object and operation

representation

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Wireless Application Environment/Wireless Application Protocol

(WAE/WAP): WAE specifies an application framework for wireless devices

and WAP is an open standard to provide mobile users access to telephony

and information services.

DIFFERENT BLUE TOOTH NETWORK S :

PICONET: Now a bluetooth network actually consists of small subnets or

piconets. A piconet consists of two or more connected nodes sharing the

same channel. Every piconet have one master and up to 7 slaves. There is

never a direct transmission between slaves. Rather all communication goes

through the master.

Figure: A Piconet

SCATTERNET: Two or more connected piconets form a scatternet. To

connect piconets simply let them have a node in common. A node may be a

slave in one piconet and a master in another. This is the basis for forming ad-hoc networks in bluetooth.

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Figure: A Scatternet

CONCLUSION:

In today’s world where wireless technology is gaining dominance and datatransfer is the demand of the day, Bluetooth is an essential technology toman through which communication can be made or data and information canbe transferred at low cost. Bluetooth has taken wireless communication to a

completely different level and has made daily life much simpler and easier.

Moreover, Bluetooth devices are not potential health hazards to mankindwhich is also an added advantage of Bluetooth over other wirelesscommunication technologies. Bluetooth uses the microwave radio frequency spectrum in the 2.402 GHz to 2.480 GHz range.[44] Maximum power outputfrom a Bluetooth radio is 100 mW, 2.5 mW, and 1 mW for Class 1, Class 2,and Class 3 devices respectively, which puts Class 1 at roughly the samelevel as mobile phones, and the other two classes much lower.[59]

Accordingly, Class 2 and Class 3 Bluetooth devices are considered less of apotential hazard than mobile phones, and Class 1 may be comparable to that

of mobile phones : the maximum for a Class 1 is 100 mW for Bluetooth but250 mW for UMTS W-CDMA, 1 W for GSM1800/1900 and 2 W for GSM850/900 for instance.

 

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  BIBLIOGRAPHY:

www.wikipedia.org

www.howstuffworks.com

www.google.com

www.bluetooth.com

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