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 collec- tion of concepts and nomenclature that are not clearly documented, and are often mis- understood. 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 es- sential 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. What mathematical dilemma is the cause for there being several definitions of bandwidth? See Section 1. See Section 3. When representing timed events, what dilemma can easily result in confusing the most-significant bit MSB and the least-significant bit LSB?
See Sec- tion 3. The error performance of digital signaling suffers primarily from two degra- dation types, a loss in signal-to-noise ratio, b distortion resulting in an irre- ducible bit-error probability. How do they differ? Explain why. See Section 4. De- scribe the behavior of each class. See Sections 4. In orthogonal signaling, why does error-performance improve with higher di- mensional signaling? Why is free-space loss a function of wavelength? See Section 5. Describe four types of trade-offs that can be accomplished by using an error- correcting code.
See Section 6. Of what use is the standard array in understanding a block code, and in eval- uating its capability? Why is the Shannon limit of See Section 8. 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? Why do binary and 4-ary orthogonal frequency shift keying FSK manifest the same bandwidth-efficiency relationship? See Section 9. Describe the subtle energy and rate transformations of received signals: from data-bits to channel-bits to symbols to chips. See Sections 1. In a fading channel, why is signal dispersion independent of fading rapidity?
See Section 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 se- nior 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 fi- nite 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 deter- mine 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 impres- sive 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, Band- pass 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. Some basic ideas of random variables and the additive white Gaussian noise AWGN model are re- viewed. Also, the relationship between power spectral density and autocorrelation, and the basics of signal transmission through linear systems are established.
Chap- ter 2 covers the signal processing step, known as formatting, in order to render an information signal compatible with a digital system. Chapter 3 emphasizes base- band signaling, the detection of signals in Gaussian noise, and receiver optimiza- tion. Chapter 5 deals with link analysis, an im- portant 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 Chap- ter 8 deals with Reed-Solomon codes and concatenated codes such as turbo codes. 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 intro- duces spread spectrum techniques and their application in such areas as multiple access, ranging, and interference rejection.
New eBooks. Search Engine. The clear, easy-to-understand introduction to digital communications Completely updated coverage of today's most critical technologies Step-by-step implementation coverage Trellis-coded modulation, fading channels, Reed-Solomon codes, encryption, and more Exclusive coverage of maximizing performance with advanced "turbo codes" "This is a remarkably comprehensive treatment of the field, covering in considerable detail modulation, coding both source and channel , encryption, multiple access and spread spectrum.
It can serve both as an excellent introduction for the graduate student with some background in probability theory or as a valuable reference for the practicing ommunication system engineer. For both communities, the treatment is clear and well presented. Digital Communications, Second Edition is a thoroughly revised and updated edition of the field's classic, best-selling introduction.
With remarkable clarity, Dr. Bernard Sklar introduces every digital communication technology at the heart of today's wireless and Internet revolutions, providing a unified structure and context for understanding them -- all without sacrificing mathematical precision.
Sklar begins by introducing the fundamentals of signals, spectra, formatting, and baseband transmission. Next, he presents practical coverage of virtually every contemporary modulation, coding, and signal processing technique, with numeric examples and step-by-step implementation guidance. Coverage includes: Signals and processing steps: from information source through transmitter, channel, receiver, and information sink Key tradeoffs: signal-to-noise ratios, probability of error, and bandwidth expenditure Trellis-coded modulation and Reed-Solomon codes: what's behind the math Synchronization and spread spectrum solutions Fading channels: causes, effects, and techniques for withstanding fading The first complete how-to guide to turbo codes: squeezing maximum performance out of digital connections Implementing encryption with PGP, the de facto industry standard Whether you're building wireless systems, xDSL, fiber or coax-based services, satellite networks, or Internet infrastructure, Sklar presents the theory and the practical implementation details you need.
With nearly illustrations and problems and exercises, there's never been a faster way to master advanced digital communications. Digital Communications. The text is flexible and can easily be used in a one semester course or there is enough depth to cover two semesters.
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