Principles of Electronics Communication system.ppt

Today, communications is the largest sector of the electronics field. In addition, wireless, networking or other communications technologies are now contained in almost every electronic product. This makes a knowledge and understanding of communication a must rather than an option for every student. Without at least one course in communications, the student may graduate with an incomplete view of the products and systems so common today.

1. MATRUSRI ENGINEERING COLLEGE
DEPARTMENT OF ELECTRONICS AND COMMUNICATION
ENGINEERING
(NBA Accredited)
SUBJECT NAME: PRINCIPLES OF ELECTRONIC COMMUNICATIONS
(OE801EC)
FACULTY NAME: Dr. M.NARESH
MATRUSRI
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2. PRINCIPLES OF ELECTRONIC COMMUNICATIONS
COURSE OBJECTIVES:
1. Provide an introduction to fundamental concepts in the understanding of
Communication Systems.
2. Provide an introduction to Network Model and some of the Network Layer
s including Physical Layer, Data link Layer , Network Layer and Transport
Layer.
3. Provide an introduction to the evaluation of Wireless Systems and current
wireless technologies.
COURSEOUTCOMES:
CO1: Learn the basics of signals, Signal transmission concepts and different
Communication parameters
CO2: Demonstrate the working of analog and digital modulation techniques
CO3: Understand the OSI network model and working of data transmission
in different layers.
CO4: Acquire the knowledge on traditional telephony system and optical
communication system..
CO5: Illustrate the evolution of various wireless systems.
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3. SYLLABUS
UNITI-Introductiontocommunicationsystems:Electromagnetic
FrequencySpectrum,Signalanditsrepresentation,Elementsof
ElectronicCommunicationsSystem,TypesofCommunication
Channels.
SignalTransmissionConcepts:Basebandtransmissionand
Broadbandtransmission.
Communication Parameters:Transmittedpower,Channel
bandwidthandNoise,Needformodulation
SignalRadiationandPropagation:Principleofelectromagnetic
radiation,TypesofAntennas,AntennaParametersandMechanisms
ofPropagation.
UNITII-AnalogandDigitalCommunications:Amplitude
modulationanddemodulation,FMmodulationanddemodulation,
Digitalconverters,Digitalmodulationschemes–ASK,FSK,PSK,
QPSK,Digitaldemodulation.
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4. UNITIV-TelecommunicationSystems:Telephones,Telephone
system,Pagingsystems,InternetTelephony.
OpticalCommunications:OpticalPrinciples,Optical
CommunicationSystems,Fiber–OpticCables,OpticalTransmitters&
Receivers,WavelengthDivisionMultiplexing.
UNITIII-DataCommunicationandNetworking:Network
Models,OSIModel,DataLinkLayer–MediaAccesscontrol,
Ethernet,NetworkLayer–InternetProtocol(IPv4/IPv6),Transport
Layer–TCP,UDP.
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UNITV-WirelessCommunications:EvolutionofWirelessSystems:
AMPS,GSM,CDMA,WCDMA,OFDM.CurrentWirelessTechnologies:
WirelessLAN,Bluetooth,PANandZigBee,Infraredwireless,RFID
communication,UWB,Wirelessmeshnetworks,Vehicularadhoc
networks.

5. LESSON PLAN:
UNIT I-Introduction to communication systems
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S. No. Topic(S)
No.
of Hrs
Text Book/
Reference
Book
1 ElectromagneticFrequencySpectrum,Signaland
itsrepresentation
1 T1
2 ElementsofElectronicCommunicationsSystem,
TypesofCommunicationChannels.
1 T1
3 Baseband transmission and Broadband
transmission.
1 T1
4 Transmittedpower,Channelbandwidthand
Noise,Needformodulation
1 T1
5 Principleofelectromagneticradiation,Typesof
Antennas
1 T1
6 Antenna ParametersandMechanisms of
Propagation
1 T1
TOTAL 6

6. TEXT BOOKS /REFERENCES
TEXTBOOKS:
1.PrinciplesofElectronicCommunicationSystems,LouisE.
Frenzel,3e,McGrawHill,2008.
2.DataCommunicationsandNetworking,BehrouzA.Forouzan,
5eTMH,2012.
3.Kennady,Davis,ElectronicCommunicationssystems,
4e,McGrawHill,1999.
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7. INTRODUCTION:
This unit deals with study of different bands of frequencies for various
applications and types of communication systems that are suitable for
a particular application and also their elements and related parameters
UNIT-I: Introduction to communication systems
OUTCOMES:
Students will be able to
Understand frequency bands and their applications.
Analyze signals and communications systems.
Define related parameters
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8. CONTENTS:
1.1 Electromagnetic frequency spectrum
1.2 Signal and its representation
OUTCOMES:
Students will be able:
•To understand different bands of frequencies used for different
applications.
•To identify various types of signals based on their representation.
MODULE-I
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9. Electromagneticfrequency spectrum
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10. Electromagneticfrequency spectrum
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11. Applications of different frequencies
Electromagneticfrequency spectrum
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12. Analog signal
Digital signal
Signal and its representation
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13. Signal and its representation
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14. 1. Write the typical frequency ranges for the following classification of EM
spectrum: MF, HF, VHF and UHF.
2. Draw the Electromagnetic Frequency Spectrum.
3. Define a signal and write its mathematical expression.
4. What are the different types of signals.
Questions & Answers
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15. CONTENTS:
1.3 Elements of electronic communications system
1.4 Types of Communication Channels
1.5 Baseband transmission and broadband transmission
OUTCOMES:
Studentswilllearn:
•Functionsofdifferentelementsofcommunicationsystem.
•Differenttypesofcommunicationchannels
•Tounderstandbasebandandbroadbandtransmissionconcepts
MODULE-2
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16. •Communication is a process of conveying message at a distance.
If the distance is involved is beyond the direct communication, the communication
engineering comes into the picture. The brain engineering which deals with
communication systems is known as telecommunication engineering.
Telecommunication engineering is classified into two types based on transmission
media. They are:
1. Line communication
2. Radio communication
Introduction to Electronic Communications System
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The transmission of information from source to the destination through a channel or
medium is called communication

17. BASIC COMMUNICATION BLOCK DIAGRAM:
Elements of Electronic Communication system
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Source: analog ordigital
Transmitter: transducer, amplifier, modulator,oscillator, poweramp., Antenna
Channel: Like Cable, optical fiber, freespace
Receiver: antenna, amplifier, demodulator, oscillator, power amplifier, Transducer
Destination : Like Person, (loud) speaker,computer

18. Types of Communication Channels
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19. Types of Communication Channels
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TWISTED PAIR

20. Types of Communication Channels
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Optical Fiber cable

21. Types of Communication Channels
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Satellite Microwave

22. Types of Communication Channels
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Terrestrial Microwave

23. Signal Transmission Concepts
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Basebandtransmission:
•Basebandtechnologyusesdigitalsignalsindatatransmission.
•Itsendsbinaryvaluesdirectlyaspulsesofdifferentvoltagelevels.
•Digitalsignalscanberegeneratedusingrepeatersinordertotravellonger
distancesbeforeweakeningandbecomingunusablebecauseofattenuation.
•Digitalsignalstravellingoverbasebandchannelwithoutfurther
conversionintoanalogsignalbymodulation
•Basebandtechnologytransmitsasingledatasignal/stream/channelata
time

24. Signal Transmission Concepts
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Broadband transmission:
•Broadbandtechnologyusesanalogsignalsindatatransmission.
•Thistechnologyusesaspecialanalogwaveknownasthecarrierwave.
•Acarrierwavedoesnotcontainanydatabutcontainsallpropertiesofthe
analogsignal.
•Thistechnologymixesdata/digitalsignal/binaryvaluesintothecarrier
waveandsendsthecarrierwaveacrossthechannel/medium.
•Totransmitdataofmultiplenodessimultaneously,thistechnologysupports
theFrequencyDivisionMultiplexing

25. Signal Transmission Concepts
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Base band transmission:
Broad band transmission using Modulation:

26. Differences between baseband and broadband transmission:
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Baseband transmission Broadband transmission
Transmit digital signals Transmit analog signals
To boost signal strength, use repeatersTo boost signal strength, use amplifiers
Can transmit only a single data stream at
a time
Can transmit multiple signal waves at a
time
Support bidirectional communication
simultaneously
Support unidirectional communication
only
Support TDM based multiplexing Support FDM based multiplexing
Use coaxial, twisted-pair, and fiber-optic
cables
Use radio waves, coaxial cables, and fiber
optic cables
Mainly used in Ethernet LAN networksMainly used in cable and telephone
networks
Signal Transmission Concepts

27. 1. Mention the elements of a communication system. Describe their
functionality with a neat diagram.
2. List the basic functions of a radio transmitter and the corresponding
functions of the receiver.
3. What are types of communication channels.
4. Explain the different types of communication channels
5. Write short notes on base band and broad band transmission.
Questions & Answers
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28. CONTENTS:
1.6Communication parameters
-Transmitted Power
-Channel Bandwidth
-Noise
-Need for Modulation
OUTCOMES:
Studentswilllearncommunicationparametersliketransmitted
power,channelbandwidth,noiseandneedformodulation
MODULE-3
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29. Transmitted power:
Let be the transmitted power radiated by an isotropic antenna.
The power density at a distance is given by
Where = Average Power
=Surface Area of an imaginary sphere of radius
Communication Parameters
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ENGINEERING COLLEGEt
P R 2
4
t
avg
P
P
R
 avg
P 2
4R R
Let be the gain of the transmitting antenna.
Then power density is given by
If is the effective aperture of receiving antenna
Then the received power of receiving antenna is given byt
G 2
4
t
avg t
P
PG
R
 e
A 2
4
t
r t e
P
P G A
R
 r
P

30. Transmitted power:
Where the antenna effective aperture is given by
= Receiving antenna gain
Then the final formula for the power received at the receiving antenna is
given by
Communication Parameters
MATRUSRI
ENGINEERING COLLEGE2
4
er
AG


 r
G 
2
2
4
t t r
r
PG G
P
R




31. Communication Parameters
MATRUSRI
ENGINEERING COLLEGE.W
HL
B f f
H
f Higher cut off frequency
L
f Lower cut off frequency
Channel Bandwidth:
Bandwidth is the difference between upper and lower frequency limits
and it is represented by
A channel is the medium through which the input signal passes.
I n terms of Analog signal : It is the range of frequencies that the channel can carry.
In terms of Digital signal: the max. bit rate supported by the channel, i. e no. of bits per
second

32. .
Communication Parameters
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•The BW of the medium should always be greater than the bandwidth of the
signal to be transmitted else loss of information takes place
•EX: Human voice range is 20Hz -20kHz
•But Voice frequency is 300 Hz-3400Hz
•So Effective speech bandwidth is 3400Hz-300Hz=3100Hz or 3.1kHz

33. Communication Parameters
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NOISE:
Noise is an un wanted signal that encounter the message signal at the channel.
noise isan error or undesired random disturbance of a useful information signal.

34. The noise signal can be understood by taking a look at the following example.
Communication Parameters
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Mostcommonexamplesofnoiseare−
•Hisssoundinradioreceivers
•Buzzsoundamidstoftelephone
conversations
•Flickerintelevisionreceivers,etc.

35. Modulation
MessageorModulatingSignal:
Thesignalwhichcontainsamessagetobetransmittediscalledasamessagesignal.
Itisabasebandsignal,whichhastoundergotheprocessofmodulation,toget
transmitted.Hence,itisalsocalledasthemodulatingsignal.
CarrierSignal:
Thehighfrequencysignal,whichhasacertainamplitude,frequencyandphasebut
containsnoinformation,iscalledasacarriersignal.Itisanemptysignalandisused
tocarrythesignaltothereceiveraftermodulation.
ModulatedSignal:
Theresultantsignalaftertheprocessofmodulationiscalledasamodulatedsignal.
Thissignalisacombinationofmodulatingsignalandcarriersignal.
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36. Need for modulation
Modulationistheprocessofchangingthecharacteristicsparameters
(amplitude,frequency,phase)ofthecarriersignal,inaccordancewiththe
instantaneousvaluesofthemodulatingsignal.
NeedforModulation:Basebandsignalsareincompatiblefordirect
transmission.Forsuchasignal,totravellongerdistances,itsstrengthhasto
beincreasedbymodulatingwithahighfrequencycarrierwave,which
doesn’taffecttheparametersofthemodulatingsignal.
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37. Need for modulation
1.Reduce the antenna height.
2.Increases the range of Communication.
3.Allows the multiplexing of signals.
4.Adjustments in the bandwidth is allowed.
5.Avoids the mixing of signals.
6.Improved reception quality
7.Narrow banding of signals.
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Need for modulation:

38. 1. Define transmitted power, channel bandwidth and noise.
2. Mention parameters of any Electronic Communication System.
3. Define noise. Where is it most likely to affect the signal?
Questions & Answers
MATRUSRI
ENGINEERING COLLEGE

39. CONTENTS:
1.7 Signal radiation and propagation
-Principle of Electromagnetic Radiation
-Types of Antenna
-Antenna parameters
-Mechanisms of Propagation
OUTCOMES:
Studentswilllearndifferenttypesofantennas,antennaparameters
,radiationpatternsandpropagationmechanisms
MODULE-4
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40. Principle of electromagnetic radiation:
ElectroMagneticRadiationorEMRisthetermusedtodescribedifferent
typesofenergiesreleasedbyelectromagneticprocess.
Visiblelight,RadioWaves,InfraredRaysandX-Raysareallformsof
electromagneticradiation.
Remotesensingtechnologiesrelayonaverityofelectromagneticenergy.
Signal Radiation and Propagation
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41. Principle of electromagnetic radiation:
ElectromagneticenergytransferredbyradiationisknownasElectromagnetic
RadiationorEMR.EMRistheonlyenergythatcantravelthroughavacuum–i.e.
space.
Light,electromagneticwaves,andradiationallrefertothesamephysical
phenomenoni.eelectromagneticenergy.
Allobjectswarmerthanabsolutezero(-273°c)emitelectromagneticradiation
(EMR).ObjectsalsoreflectandabsorbEMRemittedbyotherobjects.
Signal Radiation and Propagation
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•Electromagneticwaveconsistsofboth
electricfieldandmagneticfield.
•Theelectricfieldandmagneticfieldare
perpendiculartoeachotherandalso
perpendiculartothedirectionof
propagation

42. Principle of electromagnetic radiation:
Electromagnetic waves are the oscillations that can propagate through
free space withvelocity of light i.e.
Signal Radiation and Propagation
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3 10 /ms

43. Types of antennas:
•Anantennaisatransducer,whichconvertselectricalpowerinto
electromagneticwavesandviceversa.
•Antennasareradiatingelementsthatareusedtotransmitand/orreceive
electromagneticwaves.
Signal Radiation and Propagation
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44. TYPES OF ANTENNAS:
Signal Radiation and Propagation
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45. Types of antennas:
Signal Radiation and Propagation
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46. Signal Radiation and Propagation
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Antenna parameters :
•Gain
•Directivity
•Antenna efficiency
•Effective aperture

47. ANTENNA PARAMETERS :
1.Gain:Gainofanantennaistheratiooftheradiationintensityinagiven
directiontotheradiationintensitythatwouldbeobtainedifthepower
acceptedbytheantennawereradiatedisotropically.Itisrepresentedby“G”
andmeasuredindecibels(dB).
Gainisgivenby
where
Signal Radiation and Propagation
MATRUSRI
ENGINEERING COLLEGEe
GD
e
Antenna Efficiency D Directivity of Antenna
2.Directivity:Theratioofmaximumradiationintensityofthesubject
antennatotheradiationintensityofanisotropicorreferenceantenna,radiating
thesametotalpoweriscalledthedirectivity.Itisrepresentedby“D”anditis
givenby: intensity
intensity
Maximum radiation of subject antenna
D
Radiation of reference antenna
 
max
0
,
D
  



48. 3.Antennaefficiency:AntennaEfficiencyistheratiooftheradiated
poweroftheantennatotheinputpoweracceptedbytheantenna.
AntennaEfficiencyisgivenby
where
Signal Radiation and Propagation
MATRUSRI
ENGINEERING COLLEGErad
e
input
P
P

e
Antenna Efficiency
rad
P Radiated Power
input
P Input Power
4. Effective aperture: Aperture Efficiency of an antenna is the ratio of the
effective radiating area to the physical area of the aperture.
The mathematical expression for the Aperture Efficiency is given by : eff
A
p
A
A



A
eff
p
where
Aperture Efficiency
A Effective Area
A Physical Area





49. Radiation patterns:
•Aradiationpatternisadiagrammaticalrepresentationofthedistribution
oftheradiatedenergyintoaspace,asafunctionofdirection.
•Graphically,weplottheelectricandmagneticfieldsasafunctionofthe
angularandradialdistancefromtheantenna.
•Whichmeansthatwerepresenttheninsphericalcoordinatesas
Theradiationpatternhasmainlobe,sidelobesandbacklobe.
•Themajorpartoftheradiatedfield,whichcoversalargerarea,is
themainlobeormajorlobe.Thisistheportionwheremaximumradiated
energyexists.Thedirectionofthislobeindicatesthedirectivityofthe
antenna.
Signal Radiation and Propagation
MATRUSRI
ENGINEERING COLLEGE , , E and H   

50. Radiation patterns:
Signal Radiation and Propagation
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ENGINEERING COLLEGE
Theotherpartsofthe
patternwheretheradiation
isdistributedsidewards
areknown asside
lobesorminorlobes.
Thesearetheareaswhere
thepoweriswasted.
Thereisotherlobe,which
isexactlyoppositetothe
directionofmainlobe.Itis
knownasbacklobe,which
isalsoaminorlobe.A
considerableamountof
energyiswastedevenhere.

51. Mechanisms of Propagation : Reflection, Diffraction, Scattering
Signal Radiation and Propagation
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52. Signal Radiation and Propagation
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Reflection:OccursWhenwavesimpinges
uponanobstructionthatismuchlarger
insizecomparetothewavelengthofthe
signal
Diffraction:Occurswhentheradiopath
betweensenderandreceiveris
obstructedbyanimpenetrablebodyand
by a surfacewith sharp
irregularities(edges)
Scattering:OccurswhentheChannel
containsobjectswhosesizesareonthe
orderofthewavelengthorlessofthe
propagationwaveandalsowhenthe
numberofobstaclesarequitelarge

53. Signal Radiation and Propagation
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Wave propagation:
•Ground wave propagation
•Space wave propagation
•Sky wave propagation

54. 1. Describe antenna parameters.
2. Explain in detail non-resonant antennas with applications.
3. An half wave dipole antenna is capable of radiating 1 KW and has 2.15 db
game over an isotropic antenna. How much power must be delivered to the
isotropic antenna to match the field strength directional antenna?
4. What are different types of antennas and explain each type of antenna.
Questions & Answers
MATRUSRI
ENGINEERING COLLEGE

55. TEXT BOOKS /REFERENCES
TEXTBOOKS:
1.PrinciplesofElectronicCommunicationSystems,LouisE.
Frenzel,3e,McGrawHill,2008.
2.DataCommunicationsandNetworking,BehrouzA.Forouzan,
5eTMH,2012.
3.Kennady,Davis,ElectronicCommunicationssystems,
4e,McGrawHill,1999.
MATRUSRI
ENGINEERING COLLEGE

56. INTRODUCTION:
This unit deals with the study of different modulation and demodulation
schemes in Analog and Digital Communication.
UNIT-II:Analog and Digital Communications
OUTCOMES:
After successful completion of this Unit students will be able to
Define modulation and demodulation.
Analyze various modulation schemes.
Differentiate analog and digital modulation systems.
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57. CONTENTS:
2.1. Amplitude modulation and demodulation
OUTCOMES:
StudentswillbeabletounderstanddifferentMODULATIONAND
DEMODULATIONSchemesandtheiradvantagesandapplications.
MODULE-I
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58. Amplitude modulation and demodulation
Modulation is the process of changing the characteristics parameters (amplitude,
frequency, phase) of the carrier signal, in accordance with the instantaneous
values of the modulating signal.
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59. Types of Modulation
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Pulse Modulation:PAM(Pulse Amplitude Modulation)
PWM(Pulse Width Modulation)
PPM(Pulse position Modulation)

60. Amplitude Modulation:
The amplitude of the carrier signal varies in accordance with the
instantaneous amplitude of the modulating signal is called amplitudemodulation .
Amplitude modulation and demodulation
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61. Amplitude modulation and demodulation
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Amplitude Modulation
Let the modulating signal be, m(t) = Amcos(2πfmt) eq., 1
and the carrier signal be, c(t)= Ac cos(2πfct) eq., 2
Amplitude Modulated signal S (t) = Ac[1+kam (t)] cos2πfct eq., 3

62. Amplitude modulation and demodulation
MATRUSRI
ENGINEERING COLLEGE( ) cos
=


mm
m
m
m
m t A t
where A Amplitude of the message signal
Angular frequency of the message signal
f Frequency of the message signal





Message signal( ) cos
=


cc
c
c
c
c t A t
where A Amplitude of the carrier signal
Angular frequency of the carrier signal
f Frequency of the carrier signal





Carrier Signal
The amplitude modulated signal will be  
 
( ) ( ) cos
= cos cos
= cos cos cos
cc
c m m c
c c m m c
AM t A m t t
A A t t
A t A t t


  




63. Amplitude modulation and demodulation
MATRUSRI
ENGINEERING COLLEGE1
( )= cos .2 cos cos
2
c c m m c
AM t A t A t t   = cos 2cos cos
2
m
c c m c
A
A t t t   2cos cos cos( ) cos( - )A B A B A B    
 
 
= cos cos( ) cos( )
2
= cos cos( ) cos( )
2
= cos cos( ) cos( )
2
= cos cos( ) cos( )
22
m
c c c m c m
mc
c c c m c m
c
cm
c c c m c m
c
c a c a
c c c m c m
A
A t t t
AA
A t t t
A
AA
A t t t
A
A m A m
A t t t
    
    
    
    
   
   
   
    m
a
c
A
where m =modulation index=
A = cos cos2 ( ) cos2 ( )
22
c a c a
c c c m c m
A m A m
A t f f t f f t     
By re-arranging

64. Where µ is “modulation index” or “depth of modulation”
Amplitude modulation and demodulation
MATRUSRI
ENGINEERING COLLEGEc
m
A
A
  
 2/
2/
minmax
minmax
AA
AA
A
A
c
m


 minmax
minmax
AA
AA



then

65. .
Amplitude modulation and demodulation
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AmplitudeDemodulation:Demodulationisakeyprocessinthe
receptionofanyamplitudemodulatedsignalswhetherusedfor
broadcastortwowayradiocommunicationsystems.Demodulationisthe
processbywhichtheoriginalinformationbearingsignal,i.e.themodulation
isextractedfromtheincomingoverallreceivedsignal.
Envelope Detector

66. .
Amplitude modulation and demodulation
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Envelope Detector
The discharging time constant RLC is very large when compared to the charging time
constant i.e.,mb
L
c
s
f
CR
f
cR
11


67. Amplitude modulation and demodulation
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Frequency Domain Representation:
Frequency Spectrum of Modulating signal
Frequency Spectrum of Modulated signal

68. Bandwidth of Amplitude Modulation:
It is defined as the difference between the higher Upper side band frequency and Lower side band
frequency.
Band width (BW)= fUSB-fLSB= fc+fm-(fc-fm)=2fm
= 2 X Message Bandwidth/highest frequency
message signal
Amplitude modulation and demodulation
MATRUSRI
ENGINEERING COLLEGE

69. Power Calculation for AMPLITUDE MODULATION
MATRUSRI
ENGINEERING COLLEGE
Let the modulating signal be, m(t) = Amcos(2πfmt)
and the carrier signal be, c(t)= Ac cos(2πfct)
Then AM equation is S (t) = Ac [1+ka m (t)] cos2πfct
S (t) = AcCos (2π fct)+Acµ /2[cos2 π(fc+fm)t]+ Acµ /2[cos2π (fc-fm)t]
Total Power: Pt= Pc+ PUSB+PLSB
Power of any signal is equal to the mean square value of the signal
Carrier power Pc = Ac
2
/2
Upper Side Band power PUSB = Ac
2
µ
2
/8
Lower Side Band power P LSB = Ac
2
µ
2
/8
Total power Pt= Pc + PLSB + PUSB
Total power Pt= Ac
2
/2 + Ac
2
µ
2
/8 + Ac
2
µ
2
/8
= Ac
2
/2 + Ac
2
µ
2
/4
= Ac
2
/2[1 + µ
2
/2]

70. Amplitude Modulation and Demodulation
MATRUSRI
ENGINEERING COLLEGE
Total power Pt= Ac
2
/2 + Ac
2
µ
2
/8 + Ac
2
µ
2
/8
= Ac
2
/2 + Ac
2
µ
2
/4
= Ac
2
/2[1 + µ
2
/2]
Total power Pt=
Total power Pt=






22
2
1
2
cA 






2
2
1

cP

71. 1. A transmitter radiates 9kw without modulation and 10.125kw after
modulation. Determine depth of modulation.
2. As related to AM, what is over modulation, under modulation and 100%
modulation?
3. Derive the expression for the amplitude modulated signal.
4.ExplainthedetectionofAMsignalsusingenvelopedetector
Questions & Answers
MATRUSRI
ENGINEERING COLLEGE

72. CONTENTS:
2.2. Frequency modulation and Demodulation
OUTCOMES:
Students will be able to define frequency modulation and differentiate
between amplitude modulation and frequency modulation
MODULE-2
MATRUSRI
ENGINEERING COLLEGE

73. Angle modulation : Angle modulation is the process by which the angle (frequency
or phase) of the carrier signal is changed in accordance with the instantaneous
amplitude of modulating or message signal.
Classified into two types such as
1. Frequency modulation (FM)
2.Phase modulation (PM)
Angle modulation schemes
MATRUSRI
ENGINEERING COLLEGE
Used for :
1. Commercial radio broadcasting
2. Television sound transmission
3. Two way mobile radio
4. Cellular radio
5. Microwave and satellite communication system
Advantages over AM:
1.Freedomfrominterference:allnaturalandexternalnoiseconsistofamplitude
variations,thusreceiverusuallycannotdistinguishbetweenamplitudeofnoiseor
desiredsignal.AMisnoisythanFM.
2.Operateinveryhighfrequencyband(VHF):88MHz-108MHz
3.Cantransmitmusicalprogramswithhigherdegreeoffidelity

74. MATRUSRI
ENGINEERING COLLEGE
Frequency modulation and demodulation
FrequencyModulation:TheFrequencyofthecarriersignalvariesinaccordancewith
theinstantaneousamplitudeofthemodulatingsignaliscalledamplitude
modulation

75. Duringtheprocessoffrequencymodulationsthefrequencyofcarriersignalischanged
inaccordancewiththeinstantaneousamplitudeofmessagesignal.Thereforethe
frequencyofcarrieraftermodulationiswrittenas
To find the instantaneous phase angle of modulated signal, integrate equation above
w.r.to ‘t’:
Frequency modulation and demodulation
MATRUSRI
ENGINEERING COLLEGE tAtm
mmcos
Message signal
Carrier signal  tAtc
cccos
Frequency modulation: tAKtAK
mmfCmfci
 cos   t
AK
tdttAKdt
m
m
mf
CmmfCii


 sincos  
Thus, we get the FM wave as:)sincos(cos)( t
AK
tAActS
m
m
mf
CCiFM


  )sincos()( ttAtS
mfCCFM
 m
mf
f
AK


Where Modulation index

76. FREQUENCY DEVIATION:
∆F is the relative placement of carrier frequency (Hz) w. r. t its un-modulated value.
Given as:
Frequency modulation and demodulation
MATRUSRI
ENGINEERING COLLEGEmfC
AK
max mfC
AK
min mfCCd
AK
minmax
 mf
d
AKf 


2 m
f
mf
f
f
AKf




;

77. BANDWIDTH:
The theoretical bandwidth is “infinity”
According to the Carson’s Rule, for large band width of β, the band width of FM
slightly greater than the total frequency execution “2??????f”
FM Bandwidth calculation
MATRUSRI
ENGINEERING COLLEGE
. )1(2
)1(2
)
1
1(2
)1(2
)22
)(2









m
m
m
m
m
m
m
m
mm
mm
f
f
fBW
fBW
fBW
or
f
f
fBW
ffBW
ffBW



78. GENERATION OF FM WAVE: Direct method:
Generation of FM wave
MATRUSRI
ENGINEERING COLLEGE )()(
2
)(
2
1)](1()(
)](1[
)(
)(1[2
1
)(
)((2
1
)(,,0)(,
2
1
00
0
0
0
0
2
1
0
0
2
1
0
0
0
00
00
00
0
tmkfftm
c
kf
ftm
c
k
tm
c
k
ftf
tm
c
k
f
tf
tm
c
k
CL
tf
tkmCL
tfthenfreqtmwhen
CL
f
i
i
i
i












79. Detection of FM wave
MATRUSRI
ENGINEERING COLLEGE
Simple Slope Detector:

80. SIMPLE SLOPE DETECTOR :
It can be seen from the diagram that changes in the slope of the filter, reflect into the linearity of the
demodulation process. The linearity is very dependent not only on the filter slope as it falls away, but
also the tuning of the receiver -it is necessary to tune the receiver off frequency and to a pint where
the filter characteristic is relatively linear.
The final stage in the process is to demodulate the amplitude modulation and this can be achieved
using a simple diode circuit. One of the most obvious disadvantages of this simple approach is the
fact that both amplitude and frequency variations in the incoming signal appear at the output.
However the amplitude variations can be removed by placing a limiter before the detector.
A variety of FM slope detector circuits may be used, but the one below shows one possible circuit
with the applicable waveforms. The input signal is a frequency modulated signal. It is applied to the
tuned transformer (T1, C1, C2 combination) which is offset from the centre carrier frequency. This
converts the incoming signal from just FM to one that has amplitude modulation superimposed upon
the signal.
This amplitude signal is applied to a simple diode detector circuit, D1. Here the diode provides the
rectification, while C3 removes any unwanted high frequency components, and R1 provides a load.
Detection of FM wave
MATRUSRI
ENGINEERING COLLEGE

81. Aphase-lockedlooporphaselockloop(PLL)isacontrolsystemthatgeneratesan
outputsignalwhosephaseisrelatedtothephaseofaninputsignal.Thereareseveral
differenttypes;thesimplestisanelectroniccircuitconsistingofavariablefrequency
oscillatorandaphasedetectorinafeedbacklooptheoscillatorgeneratesaperiodic
signal,andthephasedetectorcomparesthephaseofthatsignalwiththephaseofthe
inputperiodicsignal,adjustingtheoscillatortokeepthephasesmatched.
Detection of FM by Phased Lock Loop (PLL)
MATRUSRI
ENGINEERING COLLEGE
Sout ( t ) Sf ( t )
Sphase( t )
Voltage Controlled
Oscillator (VCO)
SVCO ( t ) = AVCO ·sin [ 0 t +  0( t )]
Sf ( t ) = Af ·cos [ c t +  ( t )]
SVCO ( t )
Phase
Detector
Low-pass
filter

82. 1. Compare AM Vs FM.
2. An FM signal with single tone modulation has a frequency deviation
of 15 KHz and a BW of 50 KHz. Find the frequency of modulating
signal.
3. Explain the generation of FM wave and any one method of
demodulating an FM wave.
4. Derive the expression for the frequency modulated signal.
Questions & Answers
MATRUSRI
ENGINEERING COLLEGE

83. CONTENTS:
2.3 Digital converters
2.4 . Digital Modulation schemes-AK,FSK,PSK,QPSK Modulation and Demodulation
OUTCOMES:
Students will be able:
To define different digital modulation schemes and differentiate them.
To learn functions of different digital demodulation schemes
MODULE-3
MATRUSRI
ENGINEERING COLLEGE

84. .
Basic Digital Communication System
MATRUSRI
ENGINEERING COLLEGE
.
DigitalcommunicationisthephysicaltransferofdataoverPoint-To-
PointorPoint-To-Multipointcommunication channel.Itistransferof
discretemessages

85. .
Digital Converters
MATRUSRI
ENGINEERING COLLEGE
Digital Converters: A converter that is used to change the analog signal to digital
is known as an analog to digital converter or ADC converter.
This converter is one kind of integrated circuit or IC that converts the signal directly
from continuous form to discrete form.
This converter can be expressed in A/D, ADC, A to D. The inverse function of DAC is
nothing but ADC

86. Digital Converters
MATRUSRI
ENGINEERING COLLEGE
Steps for Convert Analog to Digital:
•Sampling
•Quantizing
•Encoding

87. AMPLITUDE SHIFT KEYING(ASK)
MATRUSRI
ENGINEERING COLLEGE
Amplitude-shiftkeying(ASK)isaformofamplitudemodulationthat
representsdigitaldataasvariationsintheamplitudeofacarrier
wave.InanASKsystem,asymbol,representingoneormorebits,issent
bytransmittingafixed-amplitudecarrierwaveatafixedfrequencyfora
specifictimeduration

88. AMPLITUDE SHIFT KEYING(ASK):
MATRUSRI
ENGINEERING COLLEGE()
()
( ) [1 ( )] cos( )
2

( ) inf (mod ) ( )
mod ( )
2

ask m c
ask
m
A
v t v t t
where v amplitude shift keying wave
v t digital ormatio ulating signal volts
A
un ulated carrier amplitude volts








log ( sec ,2 )
cc
ana carrier radian frequency radians per ond f t ()
( ) 1 1 ( ) 1 0
( ) 1 ( ) 1
( ) [1 1] cos( )
2
mm
mm
ask c
Let v t V for Logic and v t V for Logic
For v t V For v t V
A
v t t 
   
   




()
( ) [1 1] cos( )
2
cos( ) =0

ask c
c
A
v t t
At







AMPLITUDE SHIFT KEYING(ASK)

89. ASK Modulation and Demodulation
MATRUSRI
ENGINEERING COLLEGE

90. FREQUENCY SHIFT KEYING(FSK)
MATRUSRI
ENGINEERING COLLEGE
Frequency-shiftkeying(FSK)isafrequencymodulationschemein
whichdigitalinformationistransmittedthroughdiscretefrequency
changesofacarriersignal.

91. FREQUENCY SHIFT KEYING(FSK):
MATRUSRI
ENGINEERING COLLEGE ()
()
( ) cos 2 ( ) t

( ) (mod ) ( )
log ( )

fsk c c m
fsk
m
c
c
v t V f v t f
where v frequncy shift keying wave
v t binary input ulating signal volts
V ana carrier amplitude volts
f ana
  



log ( )
( ) log ( )
carrier center frequency hertz
f peak change shift in ana carrier center frequency hertz
FREQUENCY SHIFT KEYING(FSK) 
()
( ) 1 1 ( ) 1 0
( ) 1 ( ) 1

( ) cos 2 t
mm
mm
fsk c c
Let v t V for Logic and v t V for Logic
For v t V For v t V
v t V f f
   
   
    
()
( ) cos 2 t
hertz
2
- ( )
fsk c c
ms
ms
v t V f f
ff
frequency Deviation f
f f absolute difference between mark and space frequency hertz
  




92. MATRUSRI
ENGINEERING COLLEGE
FREQUENCY SHIFT KEYING(FSK)
FSK,inthemostbasiccase,representsa1(amark)byonefrequencyand
a0(aspace)byanother.Thesefrequenciesliewithinthebandwidthofthe
transmissionchannel.

93. FSK Modulation and Demodulation
MATRUSRI
ENGINEERING COLLEGE
FSK Modulator

94. MATRUSRI
ENGINEERING COLLEGE
PHASE SHIFT KEYING(PSK)
Phase-shiftkeyingisadigitalmodulationprocesswhichconveysdataby
changingthephaseofaconstantfrequencyreferencesignal.

95. Binary phase shift keying(BPSK):
MATRUSRI
ENGINEERING COLLEGE
Binary Phase Shift Keying( BPSK)

96. BINAR PHASE SHIFT KEYING(BPSK):
MATRUSRI
ENGINEERING COLLEGE
Generation:
Detection:
Generation and Detection of Binary Phase Shift Keying( BPSK)

97. MATRUSRI
ENGINEERING COLLEGE
QuadraturePhase Shift Keying(QPSK)
QPSKisaformofPhaseShiftKeyinginwhichtwobitsaremodulatedat
once,selectingoneoffourpossiblecarrierphaseshifts.
QPSKallowsthesignaltocarrytwiceasmuchinformationasordinaryPSK
usingthesamebandwidth

98. MATRUSRI
ENGINEERING COLLEGE
QuadraturePhase Shift Keying(QPSK)
Constellation Diagram
QPSK

99. QuadraturePhase Shift Keying(QPSK):
MATRUSRI
ENGINEERING COLLEGE
Generation:
Detection:
Generation and Detection of QuadraturePhase Shift Keying(QPSK)

100. 1. Define ASK, FSK and PSK modulation schemes and draw them.
2. Sketch the waveform of PSK for binary sequence 1100101.
3. Differentiate QPSK and BPSK.
4. Differentiate ASK and FSK.
5. Explain the Generation of BPSK with neat diagram.
6. Draw the block diagrams of ASK & FSK and explain with wave forms.
7. Explain the Demodulation of BASK with neat diagram.
8. Explain the Demodulation of BPSK with neat diagram.
Questions & Answers
MATRUSRI
ENGINEERING COLLEGE

101. INTRODUCTION:
This unit describes data communications components, data representation,
data flow, network structure, topologies, categories and network models.
.
OUTCOMES:
After successful completion of this Unit students will be able to
Understand the concepts of data communications and networking.
Understand the principles and concepts of network models.
MATRUSRI
ENGINEERING COLLEGE
UNIT-III: Data Communication and Networking

102. CONTENTS:
3.1Components of a data communications system
3.2 Network Models
OUTCOMES:
Studentswillbeable
To understand the Data Communications System and its components.
Familiarizewiththebasictaxonomyandterminologyofthecomputer
networkingarea.
Toidentifythedifferenttypesofnetworktopologies
MODULE-1
MATRUSRI
ENGINEERING COLLEGE

103. .
UNIT-III: Data Communication and Networking
MATRUSRI
ENGINEERING COLLEGE
Datacommunications aretheexchangeofdatabetweentwodevices
viasomeformoftransmissionmediumsuchasawirecable.
Fordatacommunicationstooccur,thecommunicatingdevicesmustbe
partofacommunicationsystemmadeupofacombinationofhardware
(physicalequipment)andsoftware(programs).Theeffectivenessofadata
communicationssystemdependsonfourfundamentalcharacteristics:
delivery,accuracy,timeliness,andjitter

104. Components of Data Communication system:
Messageis the information (data) include text, numbers, pictures, audio, and video.
Sender can be a computer, workstation, telephone handset, video camera, and so on.
Receiver can be a computer, workstation, telephone handset, television, and so on.
Ttransmission medium include twisted-pair wire, coaxial cable, fiber-optic cable, and
radio waves
Protocolis a set of rules that govern data communications. it represents an agreement
between the communicating devices.
UNIT-III: Data Communication and Networking
MATRUSRI
ENGINEERING COLLEGE

105. UNIT-III: Data Communication and Networking
MATRUSRI
ENGINEERING COLLEGE
Data Flow:

106. .
Network models
MATRUSRI
ENGINEERING COLLEGE
A network is a set of devices (often referred to as nodes) connected by
communication links.
A node can be a computer, printer, or any other device capable of sending
and/or receiving data generated by other nodes on the network.
A link can be a cable, air, optical fiber, or any medium which can transport
a signal carrying information.
•Performance
•Depends on Network Elements
•Measured in terms of Delay and Throughput
•Reliability
•Failure rate of network components
•Measured in terms of availability/robustness
•Security
•Data protection against corruption/loss of data due to:
•Errors
•Malicious users

107. Type of connection
1. Point to point -single transmitter and receiver
2. Multipoint -multiple recipients of single transmission
Network models
MATRUSRI
ENGINEERING COLLEGE

108. .
Physical Topology
MATRUSRI
ENGINEERING COLLEGE
The term physical topologyrefers to the way in which a network is laid out
physically.: one or more devices connect to a link; two or more links form a
topology.
The topology of a network is the geometric representation of the relationship
of all the links and linking devices (usually called nodes) to one another.
There are four basic topologies possible:

109. Mesh and Star Topology
MATRUSRI
ENGINEERING COLLEGE
1.Fully connected
2. Robust
3. Not flexible
1. Every node has its own dedicated
connection
2. Acts as a repeater for data flow.
3. Used with twisted cable, optical fiber or
coaxial cable.
Mesh: Star:

110. Bus and Ring Topology
MATRUSRI
ENGINEERING COLLEGE
1. Transmits data only in one direction.
2. Every device is connected to single cable only.
1. A number of repeaters are used with large number of nodes to prevent data loss.
2. Data is transferred in a sequential manner.
Bus:
Ring:

111. 1. Combination of two or topologies.
2. A star backbone with bus networks
3. Inherits the advantages and disadvantages of the topologies included
Hybrid Topology
MATRUSRI
ENGINEERING COLLEGE

112. .
•Local Area Networks (LANs)
•Short distances
•Designed to provide local interconnectivity
•Wide Area Networks (WANs)
•Long distances
•Provide connectivity over large areas
•Metropolitan Area Networks (MANs)
•Provide connectivity over areas such as a city, a campus
Categories of Networks
MATRUSRI
ENGINEERING COLLEGE

113. 1. Private networks, not subject to
tariffs or other regulatory controls.
2. Operate at relatively high speed
when compared to the typical WAN.
3. Different types of media access
control methods in a LAN, the
prominent ones are Ethernet, token
ring.
4. Connects computers in a single
building, block or campus, i.e. they
work in a restricted geographical
area.
Local Area Network (LAN)
MATRUSRI
ENGINEERING COLLEGE

114. 1. Covers towns and cities (50 km)
2. Communication medium used
are optical fibers, cables etc.
3. Data rates adequate for
distributed computing applications.
Metropolitan Area Network (MAN)
MATRUSRI
ENGINEERING COLLEGE

115. 1. Covers large distances(states, countries, continents).
2. Communication medium used are satellite, public telephone networks which are
connected by routers.
Wide Area Network (WAN)
MATRUSRI
ENGINEERING COLLEGE

116. 1. Draw & explain the functionality of different blocks of a data
communication system.
2. What is network topology and explain the different network
topologies.
3. What are the different type of networks? Explain in detail.
4. Comparison of different type of networks
Questions & Answers
MATRUSRI
ENGINEERING COLLEGE

117. CONTENTS:
OSI MODEL
Layered Architecture
Peer-to-peerProcesses
Encapsulation
OUTCOMES:
Student will able to enumerate the layers of the OSI model and explain the
function(s) of each layer.
MODULE-2
MATRUSRI
ENGINEERING COLLEGE

118. OSI model
MATRUSRI
ENGINEERING COLLEGE
1.Establishedin1947,theInternationalStandardsOrganization(ISO)isa
multinationalbodydedicatedtoworldwideagreementoninternational
standards.
2.AnISOstandardthatcoversallaspectsofnetworkcommunicationsis
theOpenSystemsInterconnection(OSI)model.
3.Itwasfirstintroducedinthelate1970s.
Responsibilities of layer in OSI Reference Model

119. Interaction between layers in the OSI model
MATRUSRI
ENGINEERING COLLEGE

120. An exchange using the OSI model
MATRUSRI
ENGINEERING COLLEGE

121. The physical layer is responsible for movements of individual bits from one
hop (node) to the next.
Functions of Physical Layer
1.Representation of Bits
2.Data Rate
3.Synchronization
4.Interface
5.Line Configuration
6.Topologies
7.Transmission Modes
Physical layer
MATRUSRI
ENGINEERING COLLEGE

122. The data link layer is responsible for moving frames from one hop (node) to
the next.
Functions of Data Link Layer
1. Framing
2. Physical Addressing
3. Flow Control
4. Error Control
5. Access Control
Data link layer
MATRUSRI
ENGINEERING COLLEGE

123. The network layer is responsible for the delivery of individual packets from
the source host to the destination host.
Functions of Network Layer:
1. Internetworking
2. Addressing
3. Routing
4. Packetizing
Network layer
MATRUSRI
ENGINEERING COLLEGE

124. Source-to-destination delivery
MATRUSRI
ENGINEERING COLLEGE

125. The transport layer is responsible for the delivery of a message from one
process to another.
Functions of Transport Layer
1. Service-point addressing
2. Segmentation and reassembly
3. Connection control
4. Flow control
5. Error control
Transport layer
MATRUSRI
ENGINEERING COLLEGE

126. Process-to-process delivery
MATRUSRI
ENGINEERING COLLEGE

127. The session layer is responsible for dialog control and synchronization.
Functions of Session Layer
1. Dialog Control
2. Token Management
3. Synchronization
Session layer
MATRUSRI
ENGINEERING COLLEGE

128. The presentation layer is responsible for translation, compression, and
encryption
Functions of Presentation layer
1. Translation
2. Encryption
3. Compression
Presentation layer
MATRUSRI
ENGINEERING COLLEGE

129. The application layer is responsible for providing services to the user.
Application layer
MATRUSRI
ENGINEERING COLLEGE

130. 1. Explain the OSI reference model with neat diagram.
2. Explain the functions of physical layer and data link layer in brief.
3. Explain the functions of network layer and transport layer in brief.
4. Explain the functions of session layer and application layer in brief.
Questions & Answers
MATRUSRI
ENGINEERING COLLEGE

131. CONTENTS:
Data link layer –media access control
Ethernet
OUTCOMES:
Student will able to enumerate the data link layer
MODULE-3
MATRUSRI
ENGINEERING COLLEGE

132. The data link layer is responsible for moving frames from one hop (node) to
the next.
Functions of Data Link Layer
1. Framing
2. Physical Addressing
3. Flow Control
4. Error Control
5. Access Control
Data link layer
MATRUSRI
ENGINEERING COLLEGE

133. Data link layer
MATRUSRI
ENGINEERING COLLEGE
The data link layer transforms the physical layer, a raw transmission facility, to a reliable
link. It makes the physical layer appear error-free to the upper layer
Communicationatthedatalinklayeroccursbetweentwoadjacentnodes.
TosenddatafromAtoF,threepartialdeliveriesaremade.
First,thedatalinklayeratAsendsaframetothedatalinklayeratB(arouter).
Second,thedatalinklayeratBsendsanewframetothedatalinklayeratE.
Finally,thedatalinklayeratEsendsanewframetothedatalinklayeratF.
Notethattheframesthatareexchangedbetweenthethreenodeshavedifferentvalues
intheheaders.
TheframefromAtoBhasBasthedestinationaddressandAasthesourceaddress.
TheframefromBtoEhasEasthedestinationaddressandBasthesourceaddress.
TheframefromEtoFhasFasthedestinationaddressandEasthesourceaddress.
Thevaluesofthetrailerscanalsobedifferentiferrorcheckingincludestheheaderof
theframe.

134. Media Access control
MATRUSRI
ENGINEERING COLLEGE
InIEEE802LAN/MANstandards,themediumaccesscontrol(MAC,alsocalledmedia
accesscontrol)sub-layeristhelayerthatcontrolsthehardwareresponsiblefor
interactionwiththewired,opticalorwirelesstransmissionmedium
TheMACsublayerandthelogicallinkcontrol(LLC)sublayertogethermakeup
thedatalinklayer.
Withinthedatalinklayer,theLLC
providesflowcontrolandmultiplexing
forthelogicallink,whiletheMAC
providesflowcontrolandmultiplexing
forthetransmissionmedium.

135. Media Access Control
MATRUSRI
ENGINEERING COLLEGE
CSMA / CD
Carrier Sense: wait till medium is idle before sending frame.
Multiple Access: multiple computers use the same shared media. Each uses same access algorithm.
Collision Detection: Listen to medium –detect if another station’s signal interferes –back off and try again later.
If collision occurs: wait a random time t
1 -0< t
1<d.
D depends on transmission speed –time for frame width or 512 bits.
If second collision occurs, wait a random time t
2 -0< t
2<2d.
Double range for each succesive collision.
Exponential backoff
No acknowledgement like TCP.
CSMA/CA used in wireless networks where not all stations receive message.
Both sides send small message followed by data:
X is about to send to Y
Y is about to receive from X
Data frame sent from X to Y.
Shared medium –stations take turns at sharing the medium.
Media access control ensures fairness.

136. Ethernet
MATRUSRI
ENGINEERING COLLEGE
Invented in 1973 @ Xerox (IEEE 802.3)
Originally a LAN technology –extended to MAN / WAN.
Same frame format, different wiring schemes, data rates across generations.
Most common version (10BaseT) –1990

137. Ethernet
MATRUSRI
ENGINEERING COLLEGE
Ethernet Generations:
NIC –Network Interface Card
MAU –Media Attachment Unit
AUI –Attachment Unit
Interface
MII –Media Independent
Interface
.

138. Ethernet
MATRUSRI
ENGINEERING COLLEGE
Ethernet Frame
48-bit address
Address assigned when NIC card is manufactured.
Packets can be sent to
Single address –Unicast
All stations on network –Broadcast (address = all 1s.)
Subset of stations –Multicast
Broadcast (address = all 1s.)
All receivers accepts unicast / broadcats.
Half addresses reserved for multicast (2
47
)
NIC can accepts zero or more multicasts.
Ethernet Addressing:

139. .
Ethernet
MATRUSRI
ENGINEERING COLLEGE
.
100Base-FX
LED light source / MMF / 2 km
max distance.
Modal dispersion –limited
bandwidth
100Base-SX(IEEE 802.3z)
Short wavelength laser (850 nm)
Max distance = 5 km.
100Base-LX
Long wavelength laser (1310
nm)
Max distance = 5 km.
Beyond Gigabit Ethernet: Recent Developments:
10 Gb/s Ethernet
No CSMS/CD, same frame format.
Applications
Upgrade LANs / Backbone.
MAN applications.

140. CONTENTS:
Network Layer-Intent Protocol (IPv4/IPv6)
OUTCOMES:
Understand the principles and concepts of internet protocols .
MODULE-4
MATRUSRI
ENGINEERING COLLEGE

141. Network Layer-Intent Protocol (IPv4/IPv6)
MATRUSRI
ENGINEERING COLLEGE
Transport segment from sending to receiving host
on sending side encapsulates segments into datagrams
on receiving side, delivers segments to transport layer
network layer protocols in everyhost, router
router examines header fields in all IP datagramspassing through it
Network Layer
Network Layer: Internet
host, router network layer functions:

142. .
Network Layer-Internet Protocol (IPv4/IPv6)
MATRUSRI
ENGINEERING COLLEGE
.
IP Datagram format
IP: the Internet Protocol
datagram format
addressing

143. Network Layer-Internet Protocol (IPv4/IPv6)
MATRUSRI
ENGINEERING COLLEGE
IP address: 32-bit identifier associated with each host or router interface
Interface:connection between
host/router and physical link.
router’s typically have multiple
interfaces.
host typically has one or two
interfaces (e.g., wired Ethernet, wireless
802.11)

144. .
MATRUSRI
ENGINEERING COLLEGE
Network Layer-Intent Protocol (IPv4/IPv6)
Pv4 stands forInternet Protocol version 4. It is the underlying technology that
makes it possible for us to connect our devices to the web. Whenever a device
accesses the Internet, it is assigned a unique, numerical IP address such as 99.48.
227.22
IPv4 frame format

145. MATRUSRI
ENGINEERING COLLEGE
priority:identify priority among datagrams in flow
flow Label:identify datagrams in same “flow.” concept of“flow” not well defined).
next header:identify upper layer protocol for data
Network Layer-Intent Protocol (IPv4/IPv6)
IPv6 datagram format

146. .
Network Layer-Internet Protocol (IPv4/IPv6)
MATRUSRI
ENGINEERING COLLEGE
.
Not all routers can be upgraded simultaneously
no “flag days”
how will network operate with mixed IPv4 and IPv6 routers?
tunneling:IPv6 datagram carried as payloadin IPv4 datagram among IPv4
routers
Transition from IPv4 to IPv6

147. Network layer-internet protocol (ipv4/ipv6)
MATRUSRI
ENGINEERING COLLEGE
IPv4andIPv6aretheactualprotocolstaskedwithdatatransmissionintheformof
packetsanddatagrams.IPv4protocolismainlyusedwithethernetsduringpacket
switchinginthelink-layernetworks.IPv6protocolbeingmorenewfangledhasimproved
capabilitiesascomparedtoIPV4

148. CONTENTS:
Transport layer –TCP, UDP
OUTCOMES:
Student will able to enumerate the layers of the TCP/IP model and explain the
function(s) of each layer.
MODULE-5
MATRUSRI
ENGINEERING COLLEGE

149. Transport layer -TCP/IP model
MATRUSRI
ENGINEERING COLLEGE

150. Transport layer -TCP/IP model
MATRUSRI
ENGINEERING COLLEGE
TCP, like UDP, is a process-to-process (program-to-program) protocol. TCP, therefore,
like UDP, uses port numbers.
TCP is called a connection-oriented, reliable transport protocol. It adds connection-
oriented and reliability features to the services of IP.
TCP Services:
Process-to-Process Communication
Stream Delivery Service
Full-Duplex Communication
Connection-Oriented Service
Reliable Service
TCP Features:
Numbering System
Flow Control
Error Control
Congestion Control
Format

151. OSI Vs TCP/IP
MATRUSRI
ENGINEERING COLLEGE
Open System Interconnection(OSI) Transmission Control Protocol(TCP)
OSImodelhasbeendevelopedbyISO(International
StandardOrganization).
ItwasdevelopedbyARPANET(AdvancedResearchProject
AgencyNetwork).
Itisanindependentstandardandgenericprotocol
usedasacommunicationgatewaybetweenthe
networkandtheenduser.
Itconsistsofstandardprotocolsthatleadtothe
developmentofaninternet.Itisacommunicationprotocol
thatprovidestheconnectionamongthehosts.
Thetransportlayerprovidesaguaranteeforthe
deliveryofthepackets.
Thetransportlayerdoesnotprovidethesuretyforthe
deliveryofpackets.Butstill,wecansaythatitisareliable
model.
Itisalsoknownasareferencemodelthroughwhich
variousnetworksarebuilt.
ItisanimplementedmodelofanOSImodel.
Thenetworklayerprovidesbothconnection-
orientedandconnectionlessservice.
Thenetworklayerprovidesonlyconnectionlessservice.
Protocolsarehiddenandcanbeeasilyreplaced
whenthetechnologychanges.
Theprotocolcannotbeeasilyreplaced.
Itconsistsof7layers. Itconsistsof4layers.
Definestheservices,protocols,andinterfacesaswell
asprovidesaproperdistinctionbetweenthem.Itis
protocolindependent.
IntheTCP/IPmodel,services,protocols,andinterfacesare
notproperlyseparated.Itisprotocoldependent.
Theusageofthismodelisverylow. Thismodelishighlyused.
Itprovidesstandardizationtothedeviceslikerouter,
motherboard,switches,andotherhardwaredevices.
Itdoesnotprovidethestandardizationtothedevices.It
providesaconnectionbetweenvariouscomputers.

152. Transport layer -User datagram protocol (UDP)
MATRUSRI
ENGINEERING COLLEGE
The original TCP/IP protocol suite specifies two protocols for the transport layer:
UDP and TCP
TheUserDatagramProtocol(UDP)iscalledaconnectionless,unreliabletransport
protocol.
ItdoesnotaddanythingtotheservicesofIPexcepttoprovideprocess-toprocess
communicationinsteadofhost-to-hostcommunication.
Also,itperformsverylimitederrorchecking.

153. Transport layer -User datagram protocol (UDP)
MATRUSRI
ENGINEERING COLLEGE
The following lists some uses of the UDP protocol:
o UDP is suitable for a process that requires simple request-response communication
with little concern for flow and error control. It is not usually used for a process
such as FrP that needs to send bulk data .
o UDP is suitable for a process with internal flow and error control mechanisms. For
example, the Trivial File Transfer Protocol (TFTP) process includes flow and error
control. It can easily use UDP.
o UDP is a suitable transport protocol for multicasting. Multicasting capability is
embedded in the UDP software but not in the TCP software.
o UDP is used for management processes such as SNMP .
o UDP is used for some route updating protocols such as Routing Information Protocol
(RIP).
UDP Process:
Connectionless Services
Flow and Error Control
Encapsulation and De-capsulation

154. Transport layer -User datagram protocol (UDP)
MATRUSRI
ENGINEERING COLLEGE
Pseudo header for checksum calculation
TheUDPchecksumcalculationisdifferentfromtheoneforIPandICMP.Herethe
checksumincludesthreesections:apseudoheader,theUDPheader,andthedata
comingfromtheapplicationlayer
If the checksum does not include the pseudo
header, a user datagram may arrive safe and
sound.
However, if the IP header is corrupted, it
may be delivered to the wrong host.
The protocol field is added to ensure that
the packet belongs to UDP, and not
to other transport-layer protocols.
If this value is changed during transmission,
the checksum calculation at the receiver will
detect it and UDP drops the packet. It is not
delivered to the wrong protocol.

155. 1. Explain the TCP/IP reference model with neat diagram.
2. Comparison between OSI model and TCP/IP model.
Questions & Answers
MATRUSRI
ENGINEERING COLLEGE

156. INTRODUCTION:
The telephone system is the largest and most complex electronic communication system
in the world. It uses just about every type of electronic communication technique
available including virtually all the ones described in this chapter
UNIT IV-Telecommunication Systems
OUTCOMES:
After successful completion of this Unit students will be able to
Acquire the knowledge of Electronic telephone system.
Describe the operation of a PBX.
Explain the operation of a facsimile machine and operation of an Internet
Protocol telephone.
Understand the concepts of Optical communication and wavelength division
multiplexing
MATRUSRI
ENGINEERING COLLEGE

157. CONTENTS:
4.1. Telephones, telephone system
OUTCOMES:
Nameanddescribedthecomponentsinconventionalandelectronictelephones.
Describedthecharacteristicsofthevarioussignalsusedintelephonecommunication.
Understandthegeneraloperationofacordlesstelephone.
MODULE-I
MATRUSRI
ENGINEERING COLLEGE

158. Telephones
MATRUSRI
ENGINEERING COLLEGE
-The original telephone system was designed for full-duplex analog communication
of voice signals.
-Today, this system is still primarily used for voice, but it employs mostly digital
techniques, not only in signal transmission but also in control operations.
The basic telephone system:

159. Telephones
MATRUSRI
ENGINEERING COLLEGE
It also contains a ringer and a dialing mechanism. Overall, the
telephone set fuli lls the following basic functions. The receive
mode provides:
1. An incoming signal that rings a bell or produces an audio tone indicating that a
call
is being received
2. A signal to the telephone system indicating that the signal has been answered
3. Transducers to convert voice to electric signals and electric signals to voice
The transmit mode:
1. Indicates to the telephone system that a call is to be made when the handset is
lifted
2. Indicates that the telephone system is ready to use by generating a signal
called the
dial tone
3. Provides a way of transmitting the telephone number to be called to the
telephone
system
4. Receives an indication that the call is being made by receiving a ringing tone
5. Provides a means of receiving a special tone indicating that the called line is
busy
6. Provides a means of signaling the telephone system that the call is complete

160. .
Telephones
MATRUSRI
ENGINEERING COLLEGE
Basic telephone set
Basic telephone set:
Ringer Hybrid
Hook switch Dialing circuit
DTMF

161. Telephones
MATRUSRI
ENGINEERING COLLEGE
DTMF
Most modern telephones use a dialing system known as Touch-Tone.
It uses pairs of audio tones to create signals representing the numbers to be dialed.
This dialing system is referred to as the dual-tone multi frequency (DTMF) system

162. Telephones
MATRUSRI
ENGINEERING COLLEGE
Standard Telephone and Local Loop:
Transmitter Central office Pulse dialing
Receiver Ring Tone dialing
Hook Switch Tip Hybrid

163. Telephone System
MATRUSRI
ENGINEERING COLLEGE
The telephone system refers to the organizations and facilities involved in connecting a telephone to
the called telephone regardless of where it might be in the united states or anywhere else in the
world.
Telephone Hierarchy:
•Wheneveryoumakeatelephonecall,yourvoiceisconnectedthroughyourlocalexchangetothe
telephonesystem.
•Fromthereitpassesthroughatleastoneotherlocalexchange,whichisconnectedtothetelephone
youarecalling.
•Severalotherfacilitiesmayprovideswitching,multiplexing,andotherservicesrequiredtotransmit
yourvoice.
•Thetelephonesystemisreferredtoasthepublicswitchedtelephonenetwork(PSTN).
•Thecentralofficeorlocalexchangeisthefacilitytowhichyourtelephoneisdirectlyconnectedbya
twisted-paircable.
•RegionalBelloperatingcompanies(RBOCs),alsocalledlocalexchangecarriers(LECs),providelocal
telephoneservice.Independentphonecompaniesprovidelocalserviceinruralareasnotservedby
RBOCs.
•TheLECsprovidetelephoneservicestodesignatedgeographicalareasreferredtoaslocalaccess
andtransportareas(LATAs).
•Long-distanceserviceisprovidedbylong-distancecarriersknownasinterexchangecarriers(IXCs).
•TheIXCsarethefamiliarlong-distancecarrierssuchasAT&T(nowSBC),WorldCom(nowVerizon),
andUSSprint.
•Long-distancecarriersmustbeusedfortheinterconnectionforanyinter-LATAconnections.

164. .
Telephone System
MATRUSRI
ENGINEERING COLLEGE
Subscriber interface : The subscriber interface or the subscriber line interface circuit (SLIC) is
comprised of a group of basic circuits that power the telephone and provide all the basic functions
such as ringing, dial tone, and dialing supervision.
BORSCHT functions in the subscriber line interface at the central office

165. .
Telephone System
MATRUSRI
ENGINEERING COLLEGE
Organization of the telephone system in the United States
The POP provides the connections to the long-distance carriers, or IXCs. The “cloud” represents the
long-distance networks of the IXCs. The long-distance network connects to the remote POPs, which
in turn are connected to other central offices and local exchanges.

166. .
Telephone System
MATRUSRI
ENGINEERING COLLEGE
Private Telephone System:
Key Systems serve 2–50 user telephones within an organization.
Individual telephone units called stations,all of which are connected to a central answering
station
The central answering station is connected to one or more local loop lines, or trunks, back to
the local exchange.
The telephone sets in a key system typically have a group of pushbuttons that allow each phone
to select two or more outgoing trunkinglines.
Private Telephone System: Private Branch Exchange
For larger organizations: thousands of individual telephones within an organization.
private automatic branch exchanges (PABXs)
computer branch exchanges (CPXs).
Advantages of efficiency and cost reduction when many telephones are required.
An alternative to PBX is Centrex.
This service performs the function of a PBX but uses special equipment and special trunk
lines.

167. Telephone System
MATRUSRI
ENGINEERING COLLEGE
PBX: PBX provides baseband interconnections to all the telephones in an organization.
The PBX offers the advantages of efficiency and cost reduction when many telephones are required.
The modern PBX is usually fully automated by computer control.

168. 1. Draw And Explain about telephone hierarchy.
2. Write short notes on telephone SYSTEM.
Questions & Answers
MATRUSRI
ENGINEERING COLLEGE

169. CONTENTS:
Paging systems,
Internet telephony
OUTCOMES:
Students will be able to Understand
the operation of paging systems
Operation of an internet protocol telephone.
MODULE-2
MATRUSRI
ENGINEERING COLLEGE

170. .
Paging systems
MATRUSRI
ENGINEERING COLLEGE
Pagingis a radio communication system designed to signal individuals wherever they may be.
Paging systems operate in the simplex mode. They broadcast signals or messages to individuals
who carry small battery-operated receivers.
To contact an individual with a pager, make a telephone call.
A paging company will send a radio signal that will be received by the pager.
The paging receiver has a built-in audible signaling device or silent vibrator that inform the
person that he or she is being paged.
Some paging receivers have a small LCD screen on which a telephone number is displayed. This
tells the paged individual which number to call.
The newest pagers are two-way devices that receive data or send data in the form of numerically
coded messages or short alphanumeric text.

171. MATRUSRI
ENGINEERING COLLEGE
Paging systems
The paging business is closely allied with the telephone business, because the telephone system
provides the initial and final communication process.
To contact a person via a pager, an individual dials the telephone number assigned to that person.
The call is received at the office of the paging company.
The paging company responds with one or more signaling tones that tell the caller to
enter the telephone number the paged person should call.
Once the number is entered, the caller presses the pound sign key to signal the end
of the telephone entry
The paging system records the telephone number in a computer and translates this
number into a serial binary-coded message.
The message is transmitted as a data bit stream to the paging receiver.
Paging systems usually operate in the VHF and UHF frequency ranges.
Most paging systems can locate an individual within a 30-mi radius

172. Paging systems
MATRUSRI
ENGINEERING COLLEGE
Each paging receiver is assigned a special code called a cap code, which is a sequence of
numbers or a combination of letters and numbers.
The cap code is broadcast over a paging region and if the pager is in the region, it will pick up
and recognize its unique code.
Thus the most widely used digital paging format is the FLEX system,developed by Motorola.
REFLEXand INFLEXIONare newer, two-way forms of FLEX.

173. .
Paging systems
MATRUSRI
ENGINEERING COLLEGE
Paging Receiver
A paging receiver is a small battery-powered superheterodyne receiver.
Most pagers use a single-chip IC receiver.
Single-and double-conversion models are available.
Direct conversion receivers (ZIF) are also used.
Most basic paging systems use some form of frequency modulation.

174. .
Internet telephony
MATRUSRI
ENGINEERING COLLEGE
.
Internettelephony,alsocalledInternetProtocol(IP)telephonyorVoiceoverInternet
Protocol(VoIP),usestheInternettocarrydigitalvoicetelephonecalls.
VoIPalmostcompletelybypassestheexistingtelephonesystem.
VoIPisahighlycomplexdigitalvoicesystemthatreliesonhigh-speedInternetconnections
fromcableTVcompanies,phonecompaniessupplyingDSL,andotherbroadbandsystems
includingwireless.
VoIPusestheInternet’svastfiber-opticcablingnetworktocarryphonecallswithoutphone
companycharges.
Inlargecompanies,VoIPisreplacingtraditionaltelephoneservicebecause:
Itoffersthebenefitsoflowerlong-distancecallingcharges
Itreducestheamountofnewequipmentneeded,sincephoneserviceisprovidedover
thesameLANthatinterconnectsthePCs.
TherearetwobasicpartstoanIPphonecall:
The“dialing”processwhichestablishesaninitialconnection
Thevoicesignalflow.

175. Internet telephony
MATRUSRI
ENGINEERING COLLEGE
Voice Signal Flow
Link Establishment
Home VoIP
Enterprise IP Phones

176. 1. Explain the concept of internet telephony.
2. Explain the operation of an internet protocol telephone.
Questions & Answers
MATRUSRI
ENGINEERING COLLEGE

177. CONTENTS:
Optical communications: Optical principles
OUTCOMES:
MODULE-3
MATRUSRI
ENGINEERING COLLEGE

178. .
Optical principles
MATRUSRI
ENGINEERING COLLEGE
.
Optical communication systemsuse light to transmit information from one place to another.
Light is a type of electromagnetic radiation like radio waves.
Today, infrared light is being used increasingly as the carrier for information in communication
systems.
The transmission medium is either free space or a light-carrying cable called a fiber-optic cable.
Because the frequency of light is extremely high, it can accommodate very high rates of data
transmission with excellent reliability.
Physical Optics: Reflection
The simplest way of manipulating light is to reflect it.
When light rays strike a reflective surface, the light waves are thrown back or reflected.
By using mirrors, the direction of a light beam can be changed.
The law of reflection states that if the light ray strikes a mirror at some angle A from the normal,
the reflected light ray will leave the mirror at the same angle B to the normal.
In other words, the angle of incidence is equal to the angle of reflection.
A light ray from the light source is called an incident ray.

179. .
Optical principles
MATRUSRI
ENGINEERING COLLEGE
Physical Optics: Refraction
The direction of the light ray can also be changed by refraction,which is the bending of a
light ray that occurs when the light rays pass from one medium to another.
Refraction occurs when light passes through transparent material such as air, water, and
glass.
Refraction takes place at the point where two different substances come together.
Refraction occurs because light travels at different speeds in different materials
The amount of refraction of the light of a material is usually expressed in terms of the index
of refraction n.
This is the ratio of the speed of light in air to the speed of light in the substance.
It is also a function of the light wavelength.

180. Optical communication systems
MATRUSRI
ENGINEERING COLLEGE
Light Wave Communication in Free Space:
An optical communication system consists of:
A light source modulated by the signal to be transmitted.
A photo detector to pick up the light and convert it back into an electrical signal.
An amplifier.
A demodulator to recover the original information signal.

181. Optical communication systems
MATRUSRI
ENGINEERING COLLEGE
Fiber-Optic Communication System
Fiber-optic cables many miles long can be constructed and interconnected for the purpose of
transmitting information.
Fiber-optic cables have immense information-carrying capacity (wide bandwidth).
Many thousands of signals can be carried on a light beam through a fiber-optic cable.

182. FIBER-OPTIC CABLES
MATRUSRI
ENGINEERING COLLEGE
Types of Fiber-Optic cables:
Step Index cable
Graded Index cable
Multi mode graded index cable

183. Optical Transmitters & Receivers
MATRUSRI
ENGINEERING COLLEGE
In an optical communication system, transmission begins with the transmitter, which consists of a
carrier generator and a modulator. The carrier is a light beam that is usually modulated by turning it
on and off with digital pulses. The basic transmitter is essentially a light source.
Thereceiverisalightorphotodetectorthatconvertsthereceivedlightbacktoanelectricsignal.In
thissection,thetypesoflightsourcesusedinfiber-opticsystemsandthetransmittercircuitry,as
wellasthevariouslightdetectorsandtherelatedreceivercircuits,

184. MATRUSRI
ENGINEERING COLLEGE
Optical Transmitters & Receivers
(a) Typical LED construction. (b) Light radiation pattern
Light-Emitting Diodes.:
A light-emitting diode (LED) is a PN-junction semi
conductor device that emits light when forward-biased.
When a free electron encounters a hole in the
semiconductor structure, the two combine, and in the
process they give up energy in the form of light.
Semiconductors such as gallium arsenide (GaAs) are
superior to silicon in light emission.
Most LEDs are GaAs devices optimized for producing red light.
LEDs are widely used for displays indicating whether a circuit is off or on, or for displaying
decimal and binary data.
However, because an LED is a fast semiconductor device, it can be turned off and on very quickly and is
capable of transmitting the narrow light pulses required in a digital Fiber optic system.

185. MATRUSRI
ENGINEERING COLLEGE
Optical Transmitters & Receivers
Laser Diodes.:
The other commonly used light transmitter is a laser, which is a
light source that emits coherent monochromatic light.
Monochromatic light is a pure single frequency light.
Although an LED emits red light, that light covers a narrow
spectrum around the red frequencies.
Coherent refers to the fact that all the light waves emitted are in
phase with one another.
Coherence produces a focusing effect on a beam so that it is narrow and, as a result, extremely intense.
The effect is somewhat similar to that of using a highly directional antenna to focus radio waves into a
narrow beam that also increases the intensity of the signal.
The most widely used light source in i ber-optic systems is the injection laser diode (ILD), also known
as a Fabry-Perot (FP) laser. Like the LED, it is a PN junction diode usually made of GaAs.

186. OPTICAL TRANSMITTERS & RECEIVERS
MATRUSRI
ENGINEERING COLLEGE
Light Detectors
The receiver part of the optical communication system is relatively simple.
It consists of a detector that senses the light pulses and converts them to an electric signal.
This signal is amplified and shaped into the original serial digital data.
The most critical component is the light sensor
Photodiode:
The most widely used light sensor is a photodiode. It is a silicon PN-junction diode that is sensitive to
light. This diode is normally reverse-biased,.
The only current that flows through it is an extremely small reverse leakage current. When light
strikes the diode, this leakage current increases significantly. This current flows through a resistor and
develops a voltage drop across it. The result is an output voltage pulse.
Phototransistor:
The reverse current in a diode is extremely small even when exposed to light. The resulting voltage
pulse is very small and so must be amplified.
The base collector junction is exposed to light.
The base leakage current produced causes a larger emitter-to-collector current to flow. Thus the
transistor amplifies the small leakage current into a larger, more useful output . Phototransistor
circuits are far more sensitive to small light levels, but they are relatively slow. Thus further
amplification and pulse shaping are normally used.

187. MATRUSRI
ENGINEERING COLLEGE
Optical Transmitters & Receivers
PIN Diode:
The sensitivity of a standard PN-junction photodiode can be increased and the response time decreased
by creating a new device that adds an un doped or intrinsic (I) layer between the P and N semiconductors.
The thin P layer is exposed to the light, which penetrates to the junction, causing electron flow
proportional to the amount of light. The diode is reverse-biased, and the current is very low until light
strikes the diode, which significantly increases the current. PIN diodes are significantly faster in response
to rapid light pulses of high frequency. And their light sensitivity is far greater than that of an ordinary
photodiode.
Structure of a PIN photodiode.

188. MATRUSRI
ENGINEERING COLLEGE
Optical Transmitters & Receivers
Avalanche Diode:
The avalanche photodiode (APD) is a more widely used photo sensor.
It is the fastest and most sensitive photodiode available, but it is expensive and its circuitry is complex.
Like the standard photodiode, the APD is reverse-biased. However, the operation is different.
The APD uses the reverse breakdown mode of operation that is commonly found in zener and IMPATT
microwave diodes.
When a sufficient amount of reverse voltage is applied, an extremely high current flows because of the
avalanche effect.
Normally, several hundred volts of reverse bias, just below the avalanche threshold, are applied.
When light strikes the junction, breakdown occurs and a large current flows.
This high reverse current requires less amplification than the small current in a standard photodiode.
Germanium APDs are also significantly faster than the other photodiodes and are capable of handling
the very high gigabit-per-second data rates possible in some systems.

189. MATRUSRI
ENGINEERING COLLEGE
Wavelength Division Multiplexing(WDM)
Data is most easily multiplexed on i ber-optic cable by using time-division multiplexing (TDM), as in the
T1 system or in the SONET system .
However, developments in optical components make it possible to use frequency-division multiplexing
(FDM) on Fuber-optic cable (called wavelength-division multiplexing, or WDM), which permits multiple
channels of data to operate over the cable’s light wave bandwidth.
Wavelength-division multiplexing, another name for frequency-division multiplexing, has been widely
used in radio, TV, and telephone systems. The best example today is the multiplexing of dozens of TV
signals on a common coaxial cable coming into the home

190. MATRUSRI
ENGINEERING COLLEGE
Wavelength Division Multiplexing(WDM
In WDM, different frequencies or “colors’’ of infrared light are employed to carry individual data streams.
These are combined and carried on a single Fiber.
Although frequency as a parameter is more widely used to distinguish the location of wireless signals
below 300 GHz, at light frequencies the wavelength parameter is the preferred measure.
Coarse Wavelength-Division Multiplexing
The first coarse WDM (CWDM) systems used two channels operating on 1310 and 1550 nm.
Later, four channels of data were multiplexed.
A separate serial data source controls each laser. The data source may be a single data source or a
multiple TDM source. Current systems use light in the 1550-nm range.
A typical four channel system uses laser wavelengths of 1534, 1543, 1550, and 1557.4 nm.
Each laser is switched off and on by the input data.
The laser beams are then optically combined and transmitted over a single Fiberc able. At the
receiving end of the cable, special optical Filters are used to separate the light beams into individual
channels. Each light beam is detected with an optical sensor and then filtered into the four data
streams.

191. Questions & Answers
MATRUSRI
ENGINEERING COLLEGE
1. Draw the block diagram of fiber optics communication system? Explain in detail.
2. What are the advantages of wavelength division multiplexing?
3. Explain classification of fibers.

192. INTRODUCTION:
Thisunitdescribesthecellphoneoperationalconcepts,thetwomost
commonsecond-generationdigitalcellphonesystemsanddifferent
wirelesstechnologieswithdifferentapplications.
UNIT-V
OUTCOMES:
After successful completion of this Unit students will be able to
Understand the concepts of cell phone systems.
Understand the different wireless technologies.
MATRUSRI
ENGINEERING COLLEGE

193. CONTENTS:
CELLULAR TELEPHONE SYSTEMS
OUTCOMES:
DESCRIBED THE ARCHITECTURE AND OPERATION OF A CELL
PHONE BASE STATION.
MODULE-I
MATRUSRI
ENGINEERING COLLEGE

194. INTRODUCTION
•Wireless refers primarily to the cellular telephone industry.
•The cell phone is the largest-volume consumer electronics device.
•It has changed the way that we communicate.
•In2005,cellphonesubscribersnumberedmorethanwiredtelephone
subscribers.
•Asthedataspeedofthenewerdigitalcellphonetransmissions
increases,morecellphoneapplicationsarepossible,including
cameras,Internetaccess,e-mails,audio,gaming,andvideo.
•Acellularradiosystemprovidesstandardtelephoneservicebytwo-
wayradioatremotelocations.
•Cellularradiosortelephoneswereoriginallyinstalledincarsortrucks,
buttodaymostofthemareavailableinhandheldmodels.
CELLULAR TELEPHONE SYSTEMS
MATRUSRI
ENGINEERING COLLEGE

195. INTRODUCTION
•Cellulartelephonespermituserstolinkupwiththe
standardtelephonesystem,whichpermitscallstoanypart
oftheworld.
•Cellularradiotelephoneserviceisavailableworldwide.
•TheoriginalU.S.cellphonesystem,knownasthe
advancedmobilephonesystem,orAMPS,wasbasedon
analogtechnologies.
•AMPShasbeenphasedoutandreplacedbysecond-
generation(2G)andthird-generation(3G)digitalcell
phonesystems.
CELLULAR TELEPHONE SYSTEMS
MATRUSRI
ENGINEERING COLLEGE

196. CELLULAR CONCEPTS
•Thebasicconceptbehindthecellularradiosystemisthatrather
thanservingagivengeographicalareawithasingletransmitterand
receiver,thesystemdividestheserviceareaintomanysmallareas
knownascells.
•Thetypicalcellcoversonlyseveralsquaremilesandcontainsits
ownreceiverandlow-powertransmitter.
•Thecoverageofacelldependsuponthedensity(number)ofusers
inagivenarea.
•Eachcellisconnectedbytelephonelinesoramicrowaveradiorelay
linktoamastercontrolcenterknownasthemobiletelephone
switchingoffice(MTSO).
•TheMTSOcontrolsallthecellsandprovidestheinterfacebetween
eachcellandthemaintelephoneoffice.
CELLULAR TELEPHONE SYSTEMS
MATRUSRI
ENGINEERING COLLEGE

197. CELLULAR CONCEPTS
•Asthepersonwiththecellphonepassesthroughacell,itisservedbythecell
transceiver.
•ThetelephonecallisroutedthroughtheMTSOandtothestandardtelephone
system.
•Asthepersonmoves,thesystemautomaticallyswitchesfromonecelltothe
next.
•Thereceiverineachcellstationcontinuouslymonitorsthesignalstrengthof
themobileunit.
•Whenthesignalstrengthdropsbelowadesiredlevel,itautomaticallyseeksa
cellwherethesignalfromthemobileunitisstronger.
•ThecomputerattheMTSOcausesthetransmissionfromthepersontobe
switchedfromtheweakercelltothestrongercell.Thisiscalledahandoff.
CELLULAR TELEPHONE SYSTEMS
MATRUSRI
ENGINEERING COLLEGE

198. The area served by a cellular telephone system is divided into small
areas called cells. Note: cells are shown as ideal hexagons, but in reality
they have circular to other geometric shapes. These areas may overlap,
and the cells may be of different sizes.
CELLULAR TELEPHONE SYSTEMS
MATRUSRI
ENGINEERING COLLEGE

199. FREQUENCY ALLOCATION
•Cellular radio systems operate in the UHF and microwave bands as
assigned by the Federal Communications Commission (FCC).
•The original frequency assignments were in the 800-to 900-MHz
range previously occupied by the mostly unused UHF TV channels 68
through 83.
•The frequencies between 824 and 849 MHz are reserved for the
uplink transmissions from the cell phone to the base station. These are
also called the reverse channels.
•The frequencies between 869 and 894 MHz are the downlink bands
from base station to cell phone.
•Two blocks of 60 MHz between 1850 and 1990 MHz are referred to
as the personal communications systems (PCS) channels.
CELLULAR TELEPHONE SYSTEMS
MATRUSRI
ENGINEERING COLLEGE

200. Additional U.S. Cell phone spectrum. (A) 890 to 960 mhzand (b) 1850 to 1990
mhzare called the personal communication system PCS band.
CELLULAR TELEPHONE SYSTEMS
MATRUSRI
ENGINEERING COLLEGE

201. MULTIPLE ACCESS
Multiple accessrefers to how the subscribers are allocated to the
assigned frequency spectrum.
Access methods are the ways in which many users share a limited
amount of spectrum.
The techniques include:
1.Frequency reuse
2.Frequency-division multiple access (FDMA)
3.Time-division multiple access (TDMA)
4.Code-division multiple access (CDMA)
5.Spatial-division multiple access (SDMA).
CELLULAR TELEPHONE SYSTEMS
MATRUSRI
ENGINEERING COLLEGE

202. FREQUENCY REUSE
•In frequency reuse, individual frequency bands are
shared by multiple base stations and users.
•This is possible by ensuring that one subscriber or base
station does not interfere with any others.
•This separation achieved by controlling such factors as
transmission power, base station spacing, and antenna
height and radiation patterns.
CELLULAR TELEPHONE SYSTEMS
MATRUSRI
ENGINEERING COLLEGE

203. FREQUENCY-DIVISION MULTIPLE ACCESS
•FDMA systems are like frequency-division multiplexing.
•They allow many users to share a block of spectrum by dividing it up
into many smaller channels.
•Each channel of a band is given an assigned number or is designated
by the center frequency of the channel.
•One subscriber is assigned to each channel.
Time-Division Multiple Access
•TDMA relies on digital signals and operates on a single channel.
•Multiple users use different time slots.
•Because the audio signal is sampled at a rapid rate, the data words
can be interleaved into different time slots.
CELLULAR TELEPHONE SYSTEMS
MATRUSRI
ENGINEERING COLLEGE

204. CODE-DIVISION MULTIPLE ACCESS
•CDMAisjustanothernameforspreadspectrum.
•Ahighpercentageofcellphonesystemsusedirectsequencespreadspectrum
(DSSS).
•Herethedigitalaudiosignalsareencodedinacircuitcalledavocodertoproduce
a13-kbpsserialdigitalcompressedvoicesignal.
•Itisthencombinedwithahigher-frequencychippingsignal.
•Auniquepseudo-randomchippingcodeisusedtoidentifymultiplesubscribers
whousethesamespectrum.
Spatial-Division Multiple Access
•Thisformofaccessisactuallyanextensionoffrequencyreuse.
•Ituseshighlydirectionalantennastopinpointusersandrejectothersonthe
samefrequency.
•Verynarrowantennabeamsatthecellsitebasestationareabletolockinon
onesubscriberbutblockanotherwhilebothsubscribersareusingthesame
frequency.
•Modernantennatechnologyusingadaptivephasedarraysmakesthis
possible.
CELLULAR TELEPHONE SYSTEMS
MATRUSRI
ENGINEERING COLLEGE

205. DUPLEXING
•Duplexingreferstothewaysinwhichtwo-wayradioortelephone
conversationsarehandled.
•Telephonecommunicationshavealwaysbeenfullduplex,whereboth
partiescansimultaneouslysendandreceive.Allcellphonesystemsarefull
duplex.
•Toachievefullduplexoperation,frequency-divisionduplexing(FDD)or
time-divisionduplexing(TDD)mustbeimplemented.
•InFDD,separatefrequencychannelsareassignedforthetransmitand
receivefunctions.
•Thetransmitandreceivechannelsarespacedsothattheydonotinterfere
withoneanotherinsidethecellphoneorbasestationcircuits.
•TDDislesscommon.Thesystemassignsthetransmitandreceivedatato
differenttimeslots,bothonthesamefrequency.
CELLULAR TELEPHONE SYSTEMS
MATRUSRI
ENGINEERING COLLEGE

206. 1. WRITE SHORT NOTES ON MULTIPLE ACCESS.
2. EXPLAIN THE CELLULAR CONCEPTS.
Questions & Answers
MATRUSRI
ENGINEERING COLLEGE

207. CONTENTS:
THE ADVANCED MOBILE PHONE SYSTEM (AMPS)
DIGITAL CELL PHONE SYSTEMS
OUTCOMES:
DESCRIBED THE BLOCK DIAGRAM ARCHITECTURE OF A MODERN
DIGITAL CELL PHONE.
MODULE-II
MATRUSRI
ENGINEERING COLLEGE

208. TYPICAL AMPS HANDSET
Although AMPS cell phones are due to be phased out beginning in
2007, millions are still in use.
An AMPS unit consists of five major sections: transmitter, receiver,
synthesizer, logic unit, and control unit.
Mobile radios derive their operating power from built-in rechargeable
batteries.
The transmitter and receiver share a single antenna.
Advanced Mobile Phone System (AMPS)
MATRUSRI
ENGINEERING COLLEGE

209. GENERAL BLOCK DIAGRAM OF A TYPICAL AMPS UNIT (CELLULAR
RADIO).
Advanced Mobile Phone System (AMPS)
MATRUSRI
ENGINEERING COLLEGE

210. TYPICAL AMPS HANDSET: TRANSMITTER & RECEIVER
•Thetransmitterisalow-powerFMunitoperatinginthefrequency
rangeof825to845MHz.
•Thetransmitter’soutputpoweriscontrollablebythecellsiteand
MTSO.
•Specialcontrolsignalspickedupbythereceiveraresenttoan
automaticpowercontrol(APC)circuitthatsetsthetransmitterto
oneofeightpoweroutputlevels.
•TheAPCfeaturepermitsoptimumcellsitereceptionwithminimal
powerandhelpsminimizeinterferencefromotherstationsinthe
sameoradjacentcells.
•Thereceiveristypicallyadual-conversionsuperheterodyne.
•Thefrequencysynthesizersectiondevelopsallthesignalsusedby
thetransmitterandreceiver.
•Thelogicunitcontainsthemastercontrolcircuitry.
Advanced Mobile Phone System (AMPS)
MATRUSRI
ENGINEERING COLLEGE

211. TYPICAL AMPS HANDSET
•Allcellularradioscontainaprogrammableread-only
memory(PROM)chipcalledthenumberassignment
module(NAM).
•TheNAMcontainsthemobileidentificationnumber
(MIN),whichisthetelephonenumberassignedtotheunit.
•Thecontrolunitcontainsthehandsetwithspeakerand
microphone.
Advanced Mobile Phone System (AMPS)
MATRUSRI
ENGINEERING COLLEGE

212. •Allnewcellphonesandsystemsusedigitalratherthananalog
methods.
•All-digitalsystemsweredevelopedtoexpandthecapacityofexisting
cellphonesystems.
•Digitaltechniquesprovideseveralwaystomultiplexmanyusersinto
thesamespectrumspace.
•Digitalsystemsaremorereliableinanoisyenvironment.
•Digitalcircuitscanbemadesmallerandmorepower-efficient,so
handsetscanbecompactandcanoperateforlongertimesonasingle
batterycharge.
•Digitalcellphonesgreatlyfacilitatethetransmissionofdata,so
servicessuchase-mailandInternetaccessarepossiblewithacell
phone.
DIGITAL CELL PHONE SYSTEMS
MATRUSRI
ENGINEERING COLLEGE

213. 2G CELL PHONE SYSTEMS
•Threebasicsecond-generation(2G)digitalcellphonesystemsarein
wideusetoday.
•Twoofthemusetime-divisionmultiplexing(TDM),andthethirduses
spreadspectrum(SS).
•TheTDMsystemsaretheGlobalSystemforMobileCommunications
(GSM)andtheIS-136standardfortimedivisionmultipleaccess(TDMA).
•TheSSsystemiscode-divisionmultipleaccess(CDMA).
Vocoder
•Tousedigitaldatatransmissiontechniquesfirstrequiresthatthevoice
bedigitized.
•Thecircuitthatdoesthisisavocoder,aspecialtypeofanalog-to-digital
(A/D)converteranddigital-to-analog(D/A)converter.
•Theconvertedserialdatasignal,representingthevoice,modulatesthe
carrierandthecompositesignaltransmittedovertheassignedchannel.
•Themainfunctionofavocoderisdatacompression.
•All2Gand3Gphonescontainavocoder.
DIGITAL CELL PHONE SYSTEMS
MATRUSRI
ENGINEERING COLLEGE

214. 2G CELL PHONE SYSTEMS
IS-136TDMA
•IS-136istheTelecommunicationsIndustryAssociation(TIA)standardthat
describesthetime-divisionmultiple-access(TDMA)cellphonesystem.
•IS-136operatesconcurrentlyonthesame800-to900-MHzbandchannelsused
byAMPSandisalsousedinthePCS-1900bands.
•TheIS-136systemprovidesforsixtimeslotsintheTDMAframe.Twotimeslots
areassignedtoeachofthreeusers.
•Spectralefficiencyisachievedwithπ/4-DQPSKmodulation,oneofthemost
efficientmodulationmethodscurrentlyavailable.
GSM
•Themostwidelyused2GdigitalsystemisGSM,orGlobalSystemforMobile
Communications.
•IntheUS,GSMiswidelyimplementedinboththe800-and1900-MHzpersonal
communicationsystemband.
•IthasmostlyreplacedtheIS-136systemsintheUS.
•LikeIS-136,GSMusesTDMA.
•Themodulationmethod,knownasGaussianminimumshiftkeying(GMSK),is
similartoFSKbutallowshigherspeedstobetransmittedinanarrowerchannel.
•GSMisthedominantcellphonetechnologyintheworld.
DIGITAL CELL PHONE SYSTEMS
MATRUSRI
ENGINEERING COLLEGE

215. 2G CELL PHONE SYSTEMS
IS-95 CDMA
•The IS-95 CDMATIA cell phone standard is called code-division multiple
access (CDMA)and is also known as CDMA One.
•CDMA uses direct sequence spread spectrum (DSSS) with a 1.2288-MHz
chipping rate that spreads the signal over a 1.25-MHz channel.
•Up to 64 users can use this band simultaneously with little or no interference
or degradation of service.
•The CDMA system uses FDD for duplexing.
•A key part of a CDMA system is APC.
DIGITAL CELL PHONE SYSTEMS
MATRUSRI
ENGINEERING COLLEGE

216. 2.5G CELL PHONE SYSTEMS
•Thedesignation2.5Greferstoagenerationofcellphonesbetween
theoriginalsecond-generation(2G)digitalphonesandnewerthird-
generation(3G)phones.
•2.5Gphonesbringdatatransmissioncapabilityto2Gphonesin
additiontonormalvoiceservice.
•A2.5Gphonepermitssubscriberstoexchangeemailsandaccessthe
Internetbycellphone.
•Thethreetechnologiesusedin2.5GsystemsareGPRS,EDGE,and
CDMA2000.
•Onepopular2.5Gtechnologyisthegeneralpacketradioservice
(GPRS).
•ThissystemisdesignedtoworkwithGSMphones.
•ItusesoneormoreoftheeighttimeslotsinaGSMphonesystemto
transmitdataratherthandigitizedvoice.
•Afaster2.5GtechnologyisenhanceddatarateforGSMevolution
(EDGE).
•Ituses8-PSKmodulationinsteadofGMSKtoachievedataratesupto
384kbps.
DIGITAL CELL PHONE SYSTEMS
MATRUSRI
ENGINEERING COLLEGE

217. 2.5G CELL PHONE SYSTEMS
CDMA2000
•Athird,differentformof2.5Gdigitalcellphoneisdesignated
CDMA2000.ThisstandardisanextensionofthewidelyusedIS-95
CDMAstandard(CDMAOne).
•ThebasicCDMA2000datatransmissionmethoduses1.25-MHz-wide
channelsbutchangesthemodulationandcodingformatstodoublethe
voicecapacity.
•Thedatacapabilityispacket-basedandpermitsadatarateofupto
144kbpswhichiscomparabletoEDGE.
•Themorerecentversioniscalled1×EV-DOorEvolution-Data
Optimized.Ithasadatarateofabout3.1Mbpsdownlinkandanuplink
rateupto1.8Mbps.
DIGITAL CELL PHONE SYSTEMS
MATRUSRI
ENGINEERING COLLEGE

218. 3G CELL PHONE SYSTEMS
•Third-generation(3G)cellphonesaretruepacketdataphones.
•3Gphonesfeatureenhanceddigitalvoiceandhigh-speeddatatransmission
capability.
•3Gapplicationsincludefaste-mailandInternetaccess.
•3Gphonesarebeingpackagedwithpersonaldigitalassistants(PDAs).
•Highspeedalsopermitsthetransmissionofvideo.
UMTS3G
•TheITUrecommendedoneworldwideversionknownaswidebandCDMA
(WCDMA)inimplementing3G.
•ThissystemisalsoknownastheUniversalMobileTelecommunications
Service(UMTS).
•WCDMAisadirectsequencespreadspectrumtechnology.
•Inthemostpopularconfiguration,itisdesignedtousea3.84-MHzchipping
ratein5-MHz-widebands.
•DuplexingisFDD,requiringthematchingof5-MHzchannels.Themodulation
isQPSK.
•Itcanachieveapacketdatarateupto2Mbps.
DIGITAL CELL PHONE SYSTEMS
MATRUSRI
ENGINEERING COLLEGE

219. 3G CELL PHONE SYSTEMS-UMTS 3G
•Akeyprobleminimplementing3Gistheneedforhugeportionsofspectrum.
•Theexact3Gspectrumvarieswidelydependingonwhichpartoftheworld
youarein,makingitextremelydifficulttodesignacellphonethatisfully
operableworldwide.
•TheUMTS3GstandardalsodefinesaTDDversionknownasTD-SCDMAfor
time-divisionsynchronouscode-divisionmultipleaccess.
•TheprimarybenefitofTD-SCDMAisthatlessspectrumisneeded.
•Becauseoftheneedforfastersystems,anewsystemcompatiblewith
WCDMAhasbeendeveloped.
•Knownashigh-speeddownlinkpacketaccess(HSDPA),thisso-called3.5G
technologyisanadd-ontoWCDMAsystems.
•HSDPAusesanadaptivecodingandmodulationschemewithQPSKand16-
QAM.
•Whenafastuplinkisneeded,acompanionstandardknownashigh-speed
uplinkpacketaccess(HSUPA)isused.
DIGITAL CELL PHONE SYSTEMS
MATRUSRI
ENGINEERING COLLEGE

220. 1. EXPLAIN THE DIFFERENT GENERATIONS IN CELLULAR PHONE
SYSTEM.
Questions & Answers
MATRUSRI
ENGINEERING COLLEGE

221. CONTENTS:
WIRELESS TECHNOLOGIES:
WIRELESS LAN
PANS AND BLUETOOTH
OUTCOMES:
•UNDERSTAND THE CONCEPTS OF PERSONAL -AREA NETWORK (PAN)
AND WIRELESS LOCAL AREA NETWORK (WLAN).
•UNDERSTAND TWO POPULAR PAN TECHNOLOGIES.
MODULE-III
MATRUSRI
ENGINEERING COLLEGE

222. WIRELESS LAN
•Inadditiontocellphones,therearemanymorewireless
systemsandapplicationsincommonusetoday.
•Theseareprimarilyshort-rangesystemsthathavea
rangeofafewinchesuptoseveralmilesdependingupon
theapplication.
•Eachofthesepopularsystemsisdefinedbyaspecific
industrystandardandisidentifiedwithoneorafewwell-
knownapplications.
WIRELESS TECHNOLOGIES
MATRUSRI
ENGINEERING COLLEGE

223. TYPES OF WLANS. (A) ACCESS POINT EXTENSION TO A WIRED LAN.
(B) PUBLIC ACCESS POINT VIA AN INTERNET SERVICE PROVIDER (ISP).
WIRELESS LAN
MATRUSRI
ENGINEERING COLLEGE

224. •Local-areanetworks(LANs)withinacompanyoranorganizationare
stillinterconnectedmainlybyCAT5orCAT6twistedpair.
•WirelessextensionsandevencompletewirelessLANshavebecome
morecommonnowthatreliable,low-costwirelessmodemsare
available.
•Wirelessisagreatwaytoexpandanexistingnetwork.
•WhatmakesthewirelessLANsoappealingisthatitoffersflexibility,
convenience,andlowercosts.
•Wirelessaccesspoints(APs)areavailablenotonlywithinoffices,
butalsoinrestaurants,coffeeshops,airports,hotels,convention
centers,andotherpublicplaces.
•Accesspointsaremorecommonlyknownas“hotspots.”Somecities
areinstallingmunicipalhotspots.
•AnyonewithalaptopequippedwithaLANmodeminterfacecanlink
uptotheAPandaccesshisorhere-mailortheInternet.Thereare
hundredsofthousandsofhotspotsaroundtheworld.
WIRELESS LAN
MATRUSRI
ENGINEERING COLLEGE

225. •AslongasthecomputeriswithintherangeoftheAP,the
connectionisautomatic.
•WirelessLANsalsoserveourcontinuingneedtobemore
mobileinourjobsandactivities.
•AnothergrowinguseofwirelessLANsisinthe
implementationofhomenetworks.
•InstallingawirelessLANisfast,easy,andveryinexpensive.A
specialboxcalledaresidentialgatewayorwirelessrouter
connectstothecableTVorDSLandservesastheaccesspoint.
•Thisgatewayorrouterusesasoftwareapproachcalled
networkaddresstranslation(NAT)tomakeitappearasif
eachnetworkedPChasitsownInternetaddress,wheninreality
onlytheoneassociatedwiththeincomingbroadbandlineis
used.
WIRELESS LAN
MATRUSRI
ENGINEERING COLLEGE

226. HARDWARE OF WIRELESS LANS
•The hardware devices in a wireless LAN are the access point or the
gateway/router and the radio modems in the PCs.
•The access point is a box containing a transceiver that interfaces to an
existing LAN by way of CAT5/6 wiring.
•It gets its dc operating power via the twisted-pair cabling.
•The IEEE 802.3af standard related to furnishing dc power over the
network cable is referred to as Power over Ethernet (PoE).
•In a home network, the gateway or router is designed to attach to the
DSL or cable TV modem with CAT5/6 cable.
•It often attaches to one of the PCs in the home network by cable.
•The other PCs link to the gateway/router wirelessly.
WIRELESS LAN
MATRUSRI
ENGINEERING COLLEGE

227. WIRELESS LAN STANDARDS
•OnestandardforwirelessLANshasemergedasthemostflexible,
affordable,andreliable.
•KnownastheIEEE802.11standard,itisavailableinmultipleforms
fordifferentneeds.
•Theearliestusefulandmostwidelyadoptedversionofthe802.11
standardis802.11b.
•Itoperatesin11channelsinthe2.4-GHzunlicensedISMband.
•Thisbandextendsfrom2.4to2.4835MHzforatotalbandwidthof
83.5MHz.
•Theaccessmethodisdirectsequencespreadspectrum(DSSS)sothat
multiplesignalsmaysharethesameband.
•The802.11bstandardspecifiesamaximumdatarateto11Mbps.
Thisrateisachievedonlyunderthemostfavorablepathconditions.
•Increasingrangeornoisecausestheratetoautomaticallydropoffto
5.5,2,or1Mbps,whichhelpsensureareliableconnectiondespitethe
lowerspeed.
WIRELESS LAN
MATRUSRI
ENGINEERING COLLEGE

228. WIRELESS LAN STANDARDS-IEEE 802.11N
•Theneweststandardisthe802.11nversion.
•Itusesthe2.4-GHzbandandOFDM.
•Aprimaryfeatureofthisstandardistheuseofmultiple-input
multiple-output(MIMO)antennasystemstoimprovereliabilityof
thelink.
•APsfor802.11nusetwoormoretransmitantennasandthreeor
morereceiveantennas.Thewirelessnodesuseasimilar
arrangement.Ineachcasemultipletransceiversarerequiredfor
theAPandthenode.
•MIMOsystemsreducemultipathproblemsandextendtherange
andreliabilityofthewirelesslink.
WIRELESS LAN
MATRUSRI
ENGINEERING COLLEGE

229. WIRELESS SECURITY
•The802.11standardalsoincludesprovisionforencryptiontoprotect
theprivacyofwirelessusers.
•Sinceradiosignalscanliterallybepickedupbyanyonewithan
appropriatereceiver,thoseconcernedaboutprivacyandsecurity
shouldusetheencryptionfeaturebuiltintothesystem.
•ThebasicsecurityprotocoliscalledWiredEquivalentPrivacy
(WEP)andusestheRC4encryptionstandardandauthentication.
•WEPmaybeturnedofforonbytheuser.Itdoesprovideabasiclevel
ofsecurity;however,WEPhasbeencrackedbyhackersandisnot
totallysecurefromthemosthigh-techdatathieves.
•TwostrongerencryptionstandardscalledWi-FiProtectedAccess
(WPA)andWPA2arealsoavailableinseveralformstofurtherboost
theencryptionprocess.
•TheIEEEalsohasasecuritystandardcalled802.11ithatprovidesthe
ultimateinprotection.
WIRELESS LAN
MATRUSRI
ENGINEERING COLLEGE

230. •Apersonal-areanetwork(PAN)isaverysmallnetworkthatis
createdinformallyoronanadhocbasis.
•APANtypicallyinvolvestwoorthreenodes,butsomesystems
permitmanynodestobeconnectedinasmallarea.
•PANscanbewired,buttodayallarewireless.
•ThemostpopularwirelessPANsystemisBluetooth,astandard
developedbythecellphonecompanyEricssonforuseasacable
replacement.
•Bluetoothisadigitalradiostandardthatusesfrequency-
hoppingspreadspectrum(FHSS)intheunlicensed2.4-GHzISM
band.
•Threelevelsoftransmissionpowerhavebeendefined,
dependingupontheapplication.
•Bluetoothtransceiversareavailableassingle-chiptransceivers
thatinterfacetothedevicetobepartofaPAN.
PANs and Bluetooth
MATRUSRI
ENGINEERING COLLEGE

231. •Bluetoothtransceiverssendoutsearchsignalsandthenlistenfornearby
Bluetooth-equippeddevices.
•IfanotherBluetoothdevicecomesintorange,thetwoBluetoothdevices
automaticallyinterconnectandexchangedata.
•Thesedevicesformwhatiscalledapiconet,thelinkingofoneBluetooth
devicethatservesasamastercontrollertouptosevenotherBluetooth
slavedevices.
•Bluetoothdevicescanalsolinktootherpiconetstoestablishlarger
scatternets.
•ThemainapplicationsforBluetootharecordlessheadsetsforcell
phones,wirelessconnectionsbetweenPCs,orlaptopcomputersandPDAs.
•Bluetoothapplicationsinclude:laptopconnectionsatmeetings,wireless
printer-to-PCconnections,laptop-to-cellphoneconnections,wireless
audioheadsets,andwirelessdigitalcamera-to-TVsetconnections.
•TheBluetoothstandardismaintainedbytheBluetoothSpecialInterest
Group(SIG)andsupportedbymorethan2000manufacturers.
PANs and Bluetooth
MATRUSRI
ENGINEERING COLLEGE

232. 1. DESCRIBE BLUETOOTH AND PAN.
Questions & Answers
MATRUSRI
ENGINEERING COLLEGE

233. CONTENTS:
ZIGBEEAND MESH WIRELESS NETWORKS
INFRARED WIRELESS
OUTCOMES:
DESCRIBED THE FEATURES, BENEFI TS, APPLICATIONS, AND
OPERATION OF THE WIRELESS TECHNOLOGIES WI -FI, ZIGBEE,
WIMAX, AND INFRARED WIRELESS.
MODULE-IV
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234. •ZigBeeisthecommercialnameforanotherPANnetwork
technologybasedontheIEEE802.15.4wirelessstandard.
•LikeBluetooth,itisashort-rangetechnologywith
networkingcapability.
•Itwasdesignedprimarilyforcommercial,industrial,and
homemonitoringandcontrolapplications.
•ZigBeeisdesignedtooperateinthelicense-free
spectrum.
•Therearethreebasicbandsandversions(below).
•Dataratesarelow,butmostapplicationsaresimply
transmittingsensordataormakingsimpleon/off
operations.
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235. •ZigBee’svirtueisitsversatilenetworkingcapability.
•Thestandardsupportsthreetopologies:star,mesh,and
clustertree.Themostcommonlyusedarethestarand
mesh.
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Frequency
Band
Number of
Channels
Modulation Max. Data Rate, Kbps
868 MHz
(Europe)
1 DSSS/BPSK 20
915 MHz 1 DSSS/BPSK 40
2.4 GHz 16 DSSS/O-QPSK 250

236. These network topologies are made up of three types of zigbeenodes:
Zigbeecoordinator (ZC)
Zigbeerouter (ZR)
Zigbeeend device (ZED).
•TheZCinitiatesanetworkformation.ThereisonlyoneZCper
network.
•TheZRservesasmonitororcontroldevicethatobservesasensoror
initiatesoff/onoperationsonsomeenddevice.
•Italsoservesasarouterasitcanreceivedatafromothernodesand
retransmitittoothernodes.
•TheZEDissimplyanendmonitororcontroldevicethatonlyreceives
dataortransmitsit.
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237. MOST COMMON ZIGBEENETWORK TOPOLOGIES. (A) STAR. (B) MESH.
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238. Popular applications of ZigBeeinclude:
•Monitoring and controlling lights;
•Heating, ventilating, and air conditioning (HVAC) systems
in large buildings;
•Industrial monitoring and control in factories, chemical
plants, and manufacturing operations.
•Automatic electric and gas meter reading.
•Medical uses, such as wireless patient monitoring.
•Automotive sensor systems.
•Military battlefield monitoring.
•Consumer applications such as home monitoring and
control, remote control of other objects, and security.
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239. •Perhaps the most widespread wireless system uses infrared (IR) light
for short-distance data communication.
•The most widely used is the wireless remote control on TV sets, VCRs,
and DVD players and on most audio CD stereo systems.
•Infrared has also been used for wireless LANs and PANs.
TV Remote Control
•Almost every TV set sold these days, regardless of size or cost, has a
wireless remote control.
•Other consumer electronic products have remote controls including
VCRs, cable TV converters, CD and DVD players, stereo audio systems,
and some ordinary radios.
•Generic remote controls are available to hook up to any device that
you wish to control remotely.
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240. TV REMOTE CONTROL
•Allremotecontroldevicesworkonthesameprinciple.
•Asmallhandheldbattery-poweredunittransmitsaserialdigitalcodevia
anIRbeamtoareceiverthatdecodesitandcarriesoutthespecificaction
definedbythecode.
•ATVremotecontrolisoneofthemoresophisticatedofthesecontrols,
foritrequiresmanycodestoperformvolumecontrol,channelselection,
andotherfunctions.
•Thekeyboardisamatrixofsingle-polesingle-throw(SPST)pushbuttons.
•Therowandcolumnconnectionsaremadetoakeyboardencodercircuit
insidetheIC.
•Whenakeyisdepressed,thepulsesfromoneofthecolumnoutputsare
connectedtooneoftherowinputs.
•Theencodercircuitconvertsthisinputtoauniquebinarycode
representinganumberforchannelselectionorsomefunctionsuchas
volumecontrol.
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241. IR TV REMOTE CONTROL TRANSMITTER
INFRARED WIRELESS
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242. THE IR RECEIVER AND CONTROL MICROPROCESSOR
INFRARED WIRELESS
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243. 1. DESCRIBE ZIGBEE AND INFRARED WIRELESS.
Questions & Answers
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244. CONTENTS:
RADIO-FREQUENCY IDENTIFICATION AND NEAR -FIELD
COMMUNICATIONS
ULTRA WIDEBAND (UWB) WIRELESS
OUTCOMES:
DESCRIBED THE FEATURES, BENEFI TS, APPLICATIONS, AND
OPERATION OF THE WIRELESS TECHNOLOGIES WI -FI, RFID AND
ULTRA WIDEBAND (UWB) WIRELESS .
MODULE-IV
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245. •Anothergrowingwirelesstechniqueisradiofrequencyidentification
(RFID).
•RFIDusesthin,inexpensivetagsorlabelscontainingpassiveradio
circuitsthatcanbequeriedbyaremotewirelessinterrogationunit.
•Thetagsareattachedtoanyitemthatistobemonitored,tracked,
accessed,located,orotherwiseidentified.
•RFIDtagsarewidelyusedininventorycontrol,containerandparcel
shipping,capitalequipmentandotherassetmanagement,baggage
handling,andmanufacturingandproductionlinetracking.
•OtherapplicationsforRFIDtagsarepersonnelsecuritycheckingand
access,animaltracking,andtheftprevention,automatictollcollection
andparkingaccessforvehicles.
•Asthetechnologydevelops,pricesdropandnewapplicationsare
beingdiscovered.
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246. •Thetagisaverythinlabel-likedeviceintowhichisembeddeda
simplepassivesingle-chipradiotransceiverandantenna.
•ThechipalsocontainsamemorythatstoresadigitalIDcodeunique
tothetaggeditem.
•Fortheitemtobeidentified,itmustpassbytheinterrogationor
readerunit,orthereadermustphysicallygotoalocationnearthe
item.
•Thereaderunitsendsoutaradiosignalthatmaytravelfromafew
inchesuptonomorethanahundredfeetorso.
•Theradiosignalisstrongenoughtoactivatethetag.
•ThetagrectifiesandfilterstheRFsignalintodirectcurrentthat
operatesthetransceiver.
•Thisactivatesalow-powertransmitterthatsendsasignalbacktothe
interrogatorunitalongwithitsembeddedIDcode.
•Thereaderchecksitsattachedcomputer,whereitnotesthepresence
oftheitemandmayperformotherprocessingtasksassociatedwith
theapplication.
RADIO-FREQUENCY IDENTIFICATION &
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247. BASIC CONCEPT AND COMPONENTS OF AN RFID SYSTEM
RADIO-FREQUENCY IDENTIFICATION &
NEAR-FILED COMMUNICATIONS
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248. RFID TAG CONFIGURATIONS
RADIO-FREQUENCY IDENTIFICATION & NEAR-
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249. NEAR-FIELD COMMUNICATIONS
•OneofthenewestformsofwirelessisaversionofRFID
callednear-fieldcommunications(NFC).
•Itisanultrashort-rangewirelesswhoserangeisrarely
morethanafewinches.
•Itisatechnologyusedinsmartcardsandcellphonesto
payforpurchasesorgainadmittancetosomefacilities.
RADIO-FREQUENCY IDENTIFICATION & NEAR-
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250. •Perhapsthenewestandmostunusualformofwirelessisknownas
ultrawideband(UWB)wireless.
•TherearetwobasicformsofUWB:theoriginalversionbasedonvery
narrowimpulses,andthenewerkindbasedonOFDM.
•TheoriginalUWB,alsoknownasimpulse,baseband,orcarrierless
wireless,transmitsdataintheformofveryshortpulses,typicallylessthan
1ns.
ImpulseUWBHardware
•TheUWBtransmittercircuitsuseBPSKtogeneratepulseswhichare
applieddirectlytotheantenna.
•Thereceiveramplifiestheincomingsignalandthenappliesittoa
correlatorconsistingofamultiplier,whereitismultipliedbyastreamof
codedpulsessimilartothosetransmitted.
•fthemultiplieroutputexceedsaspecificlevel,itisconsideredtobe
detectedandrecovered.
•Therecognizedsignalisthendemodulatedintotheoriginaldata.
•BroadbandantennasareusedforUWB.
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251. MULTIBAND OFDM UWB
•ThenewestformofUWBiscalledmultibandOFDMorMB-OFDM
UWB.
•ThisformofUWBdividesthelowerendoftheassignedspectrum
intothree528-MHz-widechannels,extendingfrom3.168to4.952
GHz.
•EachbandisdesignedtoholdanOFDMdatasignal.
•Thereare128carriersperband:100carrythedata;12areusedas
pilotcarriers;theremainingonesserveasguardbands.
•Thesignalisdividedupamongthecarriers,andeachismodulatedby
BPSKorQPSKdependingonthedataspeedselected.
•Thesystempermitsawiderangeofdataratesfromabout53to480
Mbps.
•ImplementationofanOFDMUWBtransceiverisjustlikethatofany
OFDMdevice.
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252. ADVANTAGES AND DISADVANTAGES OF UWB
•UWBoffersmanybenefitstoradar,imaging,andcommunication
applications:
•Superiorresolutioninradarandimaging.
•Immunitytomultipathpropagationeffects.
•Higherdataratesthanarepossiblewithotherwirelesstechnologies.
•License-freeoperation
•Nointerferencetoothersignalsusingthesamefrequencyband.UWB
signalsappearasrandomnoisetoconventionalradios.
•Power-efficient.Extremelylow-poweroperation.Peakpowerlevels
areinthemilliwattregion,andaveragepowerinmicrowatts.
•Thislowpowerseverelylimitstherangeofoperation.
•Simplecircuitry,mostofwhichcanbeintegratedinstandardCMOS.
•Potentiallylowcost.
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253. PRIMARY APPLICATION OF UWB
•TheprimaryapplicationofimpulseUWBtodatehas
beeninmilitaryradar.
•UWBradarisusedbyfire,emergency,andpolice
personneltoseethroughwallsanddoors.
•Medicalversionspermitbodyimagingfordiagnosis.
•Low-cost,short-rangeUWBradarsthatcanbeusedin
carsandtrucksforcollisionavoidance,automaticbraking,
improvedairbagdeployment,andsuspensionsystemsare
underdevelopment.
•TargetmarketsforUWBincludecomputerperipherals
andwirelesslyconnectingvideoequipment.
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254. 1. COMPARE MERITS AND DEMERITS OF RFID AND UWB.
Questions & Answers
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