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DIGITAL COMMUNICATIONS: FUNDAMENTALS AND APPLICATIONS 2ND EDITION

Titre :

DIGITAL COMMUNICATIONS: FUNDAMENTALS AND APPLICATIONS 2ND EDITION

Caractéristiques :


Auteur(s) :SKLAR
Editeur :PRENTICE HALL
Parution :01/2001
Langue :Anglais Anglais
Nbre de pages :1024
ISBN :978-0-13-084788-1
Reliure :MIXED MEDIA-PAK
Prix :55.00 € ttc
Disponibilité :Livraison sous 2 à 10 jours ouvrables.

Couverture :


DIGITAL COMMUNICATIONS: FUNDAMENTALS AND APPLICATIONS 2ND EDITION

Résumé :


Exceptionally accessible, this book presents the
often "difficult" concepts of digital communications in an
easy-to- understand manner-without diluting the
mathematical precision. Using a student-friendly approach,
it develops the important techniques in the context
of a unified structure (in block diagram form)-providing
organization and structure to a field that has, and
continues, to grow rapidly, and ensuring that students
gain an awareness of the "big picture" even while
delving into the details (the most up-to-date modulation,
coding, and signal processing techniques that have
become the basic tools of our modern era). It traces
signals and key processing steps from the
information source through the transmitter, channel, receiver,
and ultimately to the information sink.

New-Expanded coverage of error-correction
coding-Particularly in the areas of Reed-Solomon codes,
turbo codes, and trellis-coded modulation.
New-A chapter on fading channels-And how to
mitigate their degrading effects. Methodically
organizes the nomenclature of fading channels,
the fading phenomena, and their effects, making
them easier to grasp.
Prepares students for disciplines such as
mobile communications, which require a basic
understanding of how such channels suffer the
effects of fading, and how to withstand these
degrading effects.
New-Expanded explanations and descriptions of
essential digital communication concepts.
New-Expanded chapter-end problem sets-Adds
question sets (and where to find the answers), as
well as CD exercises.
New-An accompanying CD-Contains a student
version of SystemView software by ELANIXr; over 30
additional communications problems (in
addition to the ones at the end of each chapter) which can
be solved by using the software; and an
extensive tutorial on digital signal processing.
Allows students to explore the textbook
concepts by viewing waveforms, and changing system
parameters in the software to see the effects
on the overall system.
Sophisticated concepts presented in an
easy-to-understand, intuitive way-Uses simple numerical
examples, including detailed step-by-step
"how-to" instructions.
Helps students readily grasp the Newest
technology, such as turbo codes, trellis-coded modulation,
fading channels, Reed- Solomon codes, PGP
encryption.
Techniques developed in the context of a
unified structure-The structure, in block diagram form,
appears at the beginning of each chapter;
blocks in the diagram are emphasized, when appropriate,
to correspond to the subject of that chapter.
Signal transformations-Organized according to
nine functional classes: Formatting and source
coding; Baseband signaling; Bandpass
signaling; Equalization; Channel coding; Multiplexing and
multiple access; Spreading; Encryption; and
Synchronization.
An emphasis on system goals and
trade-offs-E.g., between basic system parameters, such as
signal-to-noise ratio, probability of error,
and bandwidth (spectral) expenditure.
Turbo codes-Features unique, thorough coverage
of turbo code concepts and "how-to" examples.
Gives students insight into the
state-of-the-art technique that allows "squeezing out the last drop" of
performance improvement that is theoretically
possible by using advanced error- correction
techniques.
Trellis-coded modulation and Reed-Solomon
error-correction codes-Goes beyond simple
mathematical description to explain all of the
sophisticated math-with analogies of what that math is
accomplishing.
Exposes students to subtle, but important
ideas-how they work and how they can be used as a
vehicle for achieving different system goals.
Pretty Good Privacy (PGP)-Explains the key
features of how PGP works and how it has evolved.
Familiarizes students to the security program
that has become the "de facto" standard for e-mail
and file encryption.
An abundance of illustrations (500) and
problems and exercises (300).


PREFACE

This second edition of Digital Communications:
Fundamentals and
Applications represents an update of the original
publication. The key features
that have been updated are:

The error-correction coding chapters have
been expanded, particularly in
the areas of Reed-Solomon codes, turbo codes,
and trellis-coded
modulation.
A new chapter on fading channels and how to
mitigate the degrading
effects of fading has been introduced.
Explanations and descriptions of essential
digital communication concepts
have been amplified.
End-of-chapter problem sets have been
expanded. Also, end-of-chapter
question sets (and where to find the
answers), as well as end-of-chapter
CD exercises have been added.
A compact disc (CD) containing an educational
version of the design
software SystemView by ELANIX accompanies the
textbook. The CD
contains a workbook with over 200 exercises,
as well as a concise
tutorial on digital signal processing (DSP).
CD exercises in the workbook
reinforce material in the textbook; concepts
can be explored by viewing
waveforms with a windows-based PC and by
changing parameters to
see the effects on the overall system. Some
of the exercises provide basic
training in using SystemView; others provide
additional training in DSP
techniques.

The teaching of a one-semester university course
proceeds in a very different
manner compared with that of a short-course in the
same subject. At the
university, one has the luxury of time_time to
develop the needed skills and
mathematical tools, time to practice the ideas
with homework exercises. In a
short-course, the treatment is almost backwards
compared with the university.
Because of the time factor, a short-course teacher
must "jump in" early with
essential concepts and applications. One of the
vehicles that I found useful in
structuring a short course was to start by handing
out a check list. This was not
merely an outline of the curriculum. It
represented a collection of concepts and
nomenclature that are not clearly documented, and
are often misunderstood.
The short-course students were thus initiated into
the course by being
challenged. I promised them that once they felt
comfortable describing each
issue, or answering each question on the list,
they would be well on their way
toward becoming knowledgeable in the field of
digital communications. I have
learned that this list of essential concepts is
just as valuable for teaching
full-semester courses as it is for short courses.
Here then is my "check list" for
digital communications.

1.What mathematical dilemma is the cause for
there being several
definitions of bandwidth? (See Section
1.7.2.)
2.Why is the ratio of bit energy-to-noise power
spectral density, Eb/N0, a
natural figure-to-merit for digital
communication systems? (See Section
3.1.5.)
3.When representing timed events, what dilemma
can easily result in
confusing the most-significant bit (MSB) and
the least-significant bit
(LSB)? (See Section 3.2.3.1.)
4.The error performance of digital signaling
suffers primarily from two
degradation types. a) loss in signal-to-noise
ratio, b) distortion resulting in
an irreducible bit-error probability. How do
they differ? (See Section
3.3.2.)
5.Often times, providing more Eb/N0 will not
mitigate the degradation due
to intersymbol interference (ISI). Explain
why. (See Section 3.3.2.)
6.At what location in the system is Eb/N0
defined? (See Section 4.3.2.)
7.Digital modulation schemes fall into one of
two classes with opposite
behavior characteristics. a) orthogonal
signaling, b) phase/amplitude
signaling. Describe the behavior of each
class. (See Section 4.8.2 and
9.7.)
8.Why do binary phase shift keying (BPSK) and
quaternary phase shift
keying (QPSK) manifest the same
bit-error-probability relationship?
Does the same hold true for M-ary pulse
amplitude modulation
(M-PAM) and M2-ary quadrature amplitude
modulation (M2-QAM)
bit-error probability? (See Sections 4.8.4
and 9.8.3.1.)
9.In orthogonal signaling, why does
error-performance improve with higher
dimensional signaling? (See Section 4.8.5.)
10.Why is free-space loss a function of
wavelength? (See Section 5.3.3.)
11.What is the relationship between received
signal to noise (S/N) ratio and
carrier to noise (C/N) ratio? (See Section
5.4.)
12.Describe four types of trade-offs that can be
accomplished by using an
error-correcting code. (See Section 6.3.4.)
13.Why do traditional error-correcting codes
yield error-performance
degradation at low values of Eb/N0? (See
Section 6.3.4.)
14.Of what use is the standard array in
understanding a block code, and in
evaluating its capability? (See Section
6.6.5.)
15.Why is the Shannon limit of -1.6 dB not a
useful goal in the design of real
systems? (See Section 8.4.5.2.)
16.16. What are the consequences of the fact that
the Viterbi decoding
algorithm does not yield a posteriori
probabilities? What is a more
descriptive name for the Viterbi algorithm?
(See Section 8.4.6.)
17.17. Why do binary and 4-ary orthogonal
frequency shift keying (FSK)
manifest the same bandwidth-efficiency
relationship? (See Section 9.5.1.)
18.18. Describe the subtle energy and rate
transformations of received
signals: from data-bits to channel-bits to
symbols to chips. (See Section
9.7.7.)
19.19. Define the following terms: Baud, State,
Communications Resource,
Chip, Robust Signal. (See Sections 1.1.3 and
7.2.2, Chapter 11, and
Sections 12.3.2 and 12.4.2.)
20.20. In a fading channel, why is signal
dispersion independent of fading
rapidity? (See Section 15.1.1.1.)

I hope you find it useful to be challenged in this
way. Now, let us describe the
purpose of the book in a more methodical way. This
second edition is intended
to provide a comprehensive coverage of digital
communication systems for
senior level undergraduates, first year graduate
students, and practicing
engineers. Though the emphasis is on digital
communications, necessary analog
fundamentals are included since analog waveforms
are used for the radio
transmission of digital signals. The key feature
of a digital communication system
is that it deals with a finite set of discrete
messages, in contrast to an analog
communication system in which messages are defined
on a continuum. The
objective at the receiver of the digital system is
not to reproduce a waveform
with precision; it is instead to determine from a
noise-perturbed signal, which of
the finite set of waveforms had been sent by the
transmitter. In fulfillment of this
objective, there has arisen an impressive
assortment of signal processing
techniques.

The book develops these techniques in the context
of a unified structure. The
structure, in block diagram form, appears at the
beginning of each chapter;
blocks in the diagram are emphasized, when
appropriate, to correspond to the
subject of that chapter. Major purposes of the
book are to add organization
and structure to a field that has grown and
continues to grow rapidly, and to
insure awareness of the "big picture" even while
delving into the details. Signals
and key processing steps are traced from the
information source through the
transmitter, channel, receiver, and ultimately to
the information sink. Signal
transformations are organized according to nine
functional classes: Formatting
and source coding, Baseband signaling, Bandpass
signaling, Equalization,
Channel coding, Muliplexing and multiple access,
Spreading, Encryption, and
Synchronization. Throughout the book, emphasis is
placed on system goals and
the need to trade off basic system parameters such
as signal-to-noise ratio,
probability of error, and bandwidth expenditure.

ORGANIZATION OF THE BOOK

Chapter 1 introduces the overall digital
communication system and the basic
signal transformations that are highlighted in
subsequent chapters. Some basic
ideas of random variables and the additive white
Gaussian noise (AWGN)
model are reviewed. Also, the relationship between
power spectral density and
autocorrelation, and the basics of signal
transmission through linear systems are
established. Chapter 2 covers the signal
processing step, known as formatting,
in order to render an information signal
compatible with a digital system.
Chapter 3 emphasizes baseband signaling, the
detection of signals in Gaussian
noise, and receiver optimization. Chapter 4 deals
with bandpass signaling and
its associated modulation and
demodulation/detection techniques. Chapter 5
deals with link analysis, an important subject for
providing overall system
insight; it considers some subtleties that are
often missed. Chapters 6, 7, and 8
deal with channel coding_a cost-effective way of
providing a variety of
system performance trade-offs. Chapter 6
emphasizes linear block codes,
Chapter 7 deals with convolutional codes, and
Chapter 8 deals with
Reed-Solomon codes and concatenated codes such as
turbo codes.

Chapter 9 considers various modulation/coding
system trade-offs dealing with
probability of bit-error performance, bandwidth
efficiency, and signal-to-noise
ratio. It also treats the important area of coded
modulation, particularly
trellis-coded modulation. Chapter 10 deals with
synchronization for digital
systems. It covers phase-locked loop
implementation for achieving carrier
synchronization. It covers bit synchronization,
frame synchronization, and
network synchronization, and it introduces some
ways of performing
synchronization using digital methods.

Chapter 11 treats multiplexing and multiple
access. It explores techniques that
are available for utilizing the communication
resource efficiently. Chapter 12
introduces spread spectrum techniques and their
application in such areas as
multiple access, ranging, and interference
rejection. This technology is important
for both military and commercial applications.
Chapter 13 deals with source
coding which is a special class of data
formatting. Both formatting and source
coding involve digitization of data; the main
difference between them is that
source coding additionally involves data
redundancy reduction. Rather than
considering source coding immediately after
formatting, it is purposely treated in
a later chapter so as not to interrupt the
presentation flow of the basic
processing steps. Chapter 14 covers basic
encryption/decryption ideas. It
includes some classical concepts, as well as a
class of systems called public key
cryptosystems, and the widely used E-mail
encryption software known as
Pretty Good Privacy (PGP). Chapter 15 deals with
fading channels. Here,
we deal with applications, such as mobile radios,
where characterization of the
channel is much more involved than that of a
nonfading one. The design of a
communication system that will withstand the
degradation effects of fading can
be much more challenging than the design of its
nonfading counterpart. In this
chapter, we describe a variety of techniques that
can mitigate the effects of
fading, and we show some successful designs that
have been implemented.

It is assumed that the reader is familiar with
Fourier methods and convolution.
Appendix A reviews these techniques, emphasizing
those properties that are
particularly useful in the study of communication
theory. It also assumed that the
reader has a knowledge of basic probability and
has some familiarity with
random variables. Appendix B builds on these
disciplines for a short treatment
on statistical decision theory with emphasis on
hypothesis testing_so important
in the understanding of detection theory. A new
section, Appendix E, has been
added to serve as a short tutorial on s-domain,
z-domain, and digital filtering. A
concise DSP tutorial also appears on the CD that
accompanies the book.

If the book is used for a two-term course, a
simple partitioning is suggested; the
first seven chapters can be taught in the first
term, and the last eight chapters in
the second term. If the book is used for a
one-term introductory course, it is
suggested that the course material be selected
from the following chapters: 1, 2,
3, 4, 5, 6, 7, 9, 10, and 12.


Bernard Sklar is Head of Advanced Systems at
Communications Engineering Services, Inc., and a visiting
lecturer at UCLA. He has over 40 years of
experience in technical design and management positions at
Republic Aviation Corporation, Hughes Aircraft,
Litton Industries, and The Aerospace Corporation. He is
author of numerous technical papers and won the
Prize Paper Award from the IEEE for a tutorial series on
digital communications.



Table of Contents

1. SIGNALS AND SPECTRA.
Digital Communication Signal Processing.
Classification of Signals. Spectral
Density. Autocorrelation. Random Signals. Signal
Transmission through
Linear Systems. Bandwidth of Digital Data.
Conclusion.

2. FORMATTING AND BASEBAND MODULATION.
Baseband Systems. Formatting Textual Data
(Character Coding).
Messages, Characters, and Symbols. Formatting
Analog Information.
Sources of Corruption. Pulse Code Modulation.
Uniform and Nonuniform
Quantization. Baseband Modulation. Correlative
Coding. Conclusion.

3. BASEBAND DEMODULATION/DETECTION.
Signals and Noise. Detection of Binary Signals
in Gaussian Noise.
Intersymbol Interference. Equalization.
Conclusion.

4. -BANDPASS MODULATION AND
DEMODULATION/_DETECTION.
Why Modulate? Digital Bandpass Modulation
Techniques. Detection of
Signals in Gaussian Noise. Coherent Detection.
Noncoherent Detection.
Complex Envelope. Error Performance for Binary
Systems. M-ary Signaling
and Performance. Symbol Error Performance for
M-ary Systems (M >2).
Conclusion.

5. COMMUNICATIONS LINK ANALYSIS.
What the System Link Budget Tells the System
Engineer. The Channel.
Received Signal Power and Noise Power. Link
Budget Analysis. Noise
Figure, Noise Temperature, and System
Temperature. Sample Link
Analysis. Satellite Repeaters. System
Trade-Offs. Conclusion.

6. CHANNEL CODING: PART 1.
Waveform Coding and Structured Sequences. Types
of Error Control.
Structured Sequences. Linear Block Codes.
Error-Detecting and Correcting
Capability. Usefulness of the Standard Array.
Cyclic Codes. Well-Known
Block Codes. Conclusion.

7. CHANNEL CODING: PART 2.
Convolutional Encoding. Convolutional Encoder
Representation.
Formulation of the Convolutional Decoding
Problem. Properties of
Convolutional Codes. Other Convolutional
Decoding Algorithms.
Conclusion.

8. CHANNEL CODING: PART 3.
Reed-Solomon Codes. Interleaving and
Concatenated Codes. -Coding and
Interleaving Applied to the Compact Disc
_Digital Audio System. Turbo
Codes. Conclusion.

Appendix 8A. The Sum of Log-Likelihood Ratios.
9. Modulation and Coding Trade-Offs.
Goals of the Communications System Designer.
Error Probability Plane.
Nyquist Minimum Bandwidth. Shannon-Hartley
Capacity Theorem.
Bandwidth Efficiency Plane. Modulation and
Coding Trade-Offs. -Defining,
Designing, and Evaluating Digital _Communication
Systems.
Bandwidth-Efficient Modulation. Modulation and
Coding for Bandlimited
Channels. Trellis-Coded Modulation. Conclusion.

10. SYNCHRONIZATION.
Introduction. Receiver Synchronization. Network
Synchronization.
Conclusion.

11. MULTIPLEXING AND MULTIPLE ACCESS.
Allocation of the Communications Resource.
Multiple Access
Communications System and Architecture. Access
Algorithms. Multiple
Access Techniques Employed with INTELSAT.
Multiple Access
Techniques for Local Area Networks. Conclusion.

12. SPREAD-SPECTRUM TECHNIQUES.
Spread-Spectrum Overview. Pseudonoise Sequences.
Direct-Sequence
Spread-Spectrum Systems. Frequency Hopping
Systems. Synchronization.
Jamming Considerations. Commercial Applications.
Cellular Systems.
Conclusion.

13. SOURCE CODING.
Sources. Amplitude Quantizing. Differential
Pulse-Code Modulation.
Adaptive Prediction. Block Coding. Transform
Coding. Source Coding for
Digital Data. Examples of Source Coding.
Conclusion.

14. ENCRYPTION AND DECRYPTION.
Models, Goals, and Early Cipher Systems. The
Secrecy of a Cipher System.
Practical Security. Stream Encryption. Public
Key Cryptosystems. Pretty
Good Privacy. Conclusion.

15. FADING CHANNELS.
The Challenge of Communicating over Fading
Channels. Characterizing
Mobile-Radio Propagation. Signal Time-Spreading.
Time Variance of the
Channel Caused by Motion. Mitigating the
Degradation Effects of Fading.
Summary of the Key Parameters Characterizing
Fading Channels.
Applications: Mitigating the Effects of
Frequency-Selective Fading.
Conclusion.

A. A REVIEW OF FOURIER TECHNIQUES.
A.1 Signals, Spectra, and Linear Systems.
Fourier Techniques for Linear
System Analysis. Fourier Transform Properties.
Useful Functions.
Convolution. Tables of Fourier Transforms and
Operations.

B. FUNDAMENTALS OF STATISTICAL DECISION THEORY.
Bayes' Theorem. Decision Theory. Signal Detection
Example.
C. RESPONSE OF A CORRELATOR TO WHITE NOISE.
D. OFTEN-USED IDENTITIES.
E. s-DOMAIN, z-DOMAIN AND DIGITAL FILTERING.
The Laplace Transform. The z-Transform. Digital
Filtering. Finite Impulse
Response Filter Design. Infinite Impulse
Response Filter Design.

F. LIST OF SYMBOLS.
INDEX.

Table des matières :

(NOTE: Each chapter concludes with a Conclusion, References, Problems, Questions, and CD Exercises.)

1. Signals and Spectra.


Digital Communication Signal Processing. Classification of Signals. Spectral Density. Autocorrelation. Random Signals. Signal Transmission through Linear Systems. Bandwidth of Digital Data.



2. Formatting and Baseband Modulation.


Baseband Systems. Formatting Textual Data (Character Coding). Messages, Characters, and Symbols. Formatting Analog Information. Sources of Corruption. Pulse Code Modulation. Uniform and Nonuniform Quantization. Baseband Modulation. Correlative Coding.



3. Baseband Demodulation/Detection.


Signals and Noise. Detection of Binary Signals in Gaussian Noise. Intersymbol Interference. Equalization.



4. Bandpass Modulation and Demodulation/Detection.


Why Modulate? Digital Bandpass Modulation Techniques. Detection of Signals in Gaussian Noise. Coherent Detection. Noncoherent Detection. Complex Envelope. Error Performance for Binary Systems. M-ary Signaling and Performance. Symbol Error Performance for M-ary Systems (M>>2).



5. Communications Link Analysis.


What the System Link Budget Tells the System Engineer. The Channel. Received Signal Power and Noise Power. Link Budget Analysis. Noise Figure, Noise Temperature, and System Temperature. Sample Link Analysis. Satellite Repeaters. System Trade-Offs.



6. Channel Coding: Part 1.


Waveform Coding. Types of Error Control. Structured Sequences. Linear Block Codes. Error-Detecting and Correcting Capability. Usefulness of the Standard Array. Cyclic Codes. Well-Known Block Codes.



7. Channel Coding: Part 2.


Convolutional Encoding. Convolutional Encoder Representation. Formulation of the Convolutional Decoding Problem. Properties of Convolutional Codes. Other Convolutional Decoding Algorithms.



8. Channel Coding: Part 3.


Reed-Solomon Codes. Interleaving and Concatenated Codes. Coding and Interleaving Applied to the Compact Disc Digital Audio System. Turbo Codes.



Appendix 8A. The Sum of Log-Likelihood Ratios.
9. Modulation and Coding Trade-Offs.

Goals of the Communications System Designer. Error Probability Plane. Nyquist Minimum Bandwidth. Shannon-Hartley Capacity Theorem. Bandwidth Efficiency Plane. Modulation and Coding Trade-Offs. Defining, Designing, and Evaluating Systems. Bandwidth-Efficient Modulations. Modulation and Coding for Bandlimited Channels. Trellis-Coded Modulation.

10. Synchronization.

Introduction. Receiver Synchronization. Network Synchronization.

11. Multiplexing and Multiple Access.

Allocation of the Communications Resource. Multiple Access Communications System and Architecture. Access Algorithms. Multiple Access Techniques Employed with INTELSAT. Multiple Access Techniques for Local Area Networks.

12. Spread-Spectrum Techniques.

Spread-Spectrum Overview. Pseudonoise Sequences. Direct-Sequence Spread-Spectrum Systems. Frequency Hopping Systems. Synchronization. Jamming Considerations. Commercial Applications. Cellular Systems.

13. Source Coding.

Sources. Amplitude Quantizing. Differential Pulse-Code Modulation. Adaptive Prediction. Block Coding. Transform Coding. Source Coding for Digital Data. Examples of Source Coding.

14. Encryption and Decryption.

Models, Goals, and Early Cipher Systems. The Secrecy of a Cipher System. Practical Security. Stream Encryption. Public Key Cryptosystems. Pretty Good Privacy.

15. Fading Channels.

The Challenge of Communicating over Fading Channels. Characterizing Mobile-Radio Propagation. Signal Time-Spreading. Time Variance of the Channel Caused by Motion. Mitigating the Degradation Effects of Fading. Summary of the Key Parameters Characterizing Fading Channels. Applications: Mitigating the Effects of Frequency-Selective Fading.

A. A Review of Fourier Techniques.

Signals, Spectra, and Linear Systems. Fourier Techniques for Linear System Analysis. Fourier Transform Properties. Useful Functions. Convolution. Tables of Fourier Transforms and Operations.

B. Fundamentals of Statistical Decision Theory.

Bayes' Theorem. Decision Theory. Signal Detection Example.

C. Response of a Correlator To White Noise.D. Often-Used Identities.E. s-Domain, z-Domain and Digital Filtering.F. List of Symbols.G. SystemView by ELANIX Guide to the CD.

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