Introduction to Digital Communications

This is an undergraduate-level textbook that lucidly provides the basic princi-ples in the analysis and design of digital communication systems. Since digitalcommunications is an advanced topic, the treatment here is more descriptiveand explanatory rather than merely rigorous. However, it is not devoid of math-ematical analyses, as all relevant results are presented. Although the mathemat-ical level of the book is intentionally constrained, the intuitive level of it is not.The premise is that complex concepts are best conveyed in the simplest possiblecontext. The goal, at every step of the way, is to provide big picture throughanalysis, description, example, and application. In taking a systems approachto digital communications, the text hardly considers actual physical realiza-tions of the devices (i.e., the systems are presented in block diagram form).There is intentionally much more in this book than can be taught in one semes-ter (of 36 lecture hours). The book consists of 12 chapters focused on digitalcommunications. Chapters 1 & 2 provide an overview of the fundamentalsof digital communications. Since digital communications at the physical layerinvolves the transmission of continuous-time signals where the channel noiseis also in the form of continuous time, Chapters 3 & 4 cover deterministic andrandom signals in detail, and should serve as review materials. Chapters 5 to 12,inclusive, discuss the critical elements and major topics in the broad field ofdigital communications. In addition, there is an appendix with a summaryof analog communications. Introduction to Digital Communications Copyright atl_0002257240_ Preface Acknowledgements Introduction Historical Review of Communications Block Diagram of a Digital Communication System Organization of the Book References Fundamental Aspects of Digital Communications Introduction Why Digital? Advantages of Digital Disadvantages of Digital Communications modalities Text Audio Visual Communication network models Layered Architectures OSI Model TCP/IP Protocol Suite Guided-Transmission Media Twisted-Pair Cable Coaxial Cable Fiber-Optic Cable Radio transmission Advantages of Radio Disadvantages of Radio Radio Spectrum Wave Propagation Transmission impairments Attenuation Distortion Interference Noise Modulation process Fundamental limits in digital transmission Digital communication design aspects Summary and Sources Signals, Systems, and Spectral Analysis Basic operations on signals Operations Performed on Dependent Variable Operations Performed on Independent Variable Classification of signals Continuous-Value and Discrete-Value Signals Continuous-Time and Discrete-Time Signals Analog and Digital Signals Deterministic and Random Signals Real and Complex Signals Periodic and Nonperiodic Signals Even and Odd Signals Energy and Power Signals Causal and Noncausal Signals Time-Limited and Band-Limited Signals Baseband and Bandpass Signals Classification of systems Baseband and Passband Systems Invertible and Noninvertible Systems Lumped and Distributed Systems Adaptive and Fixed Systems Systems with or without Feedback Systems with or without Memory Systems with Single/Multiple Inputs and Single/Multiple Outputs Passive and Active Systems Causal and Noncausal Systems Stable and Unstable Systems Continuous-Time and Discrete-Time Systems Power-Limited and Band-Limited Systems Linear and Nonlinear Systems Time-Invariant and Time-Varying Systems Linear Time-Invariant LTI Systems Sinsuoidal signals Characteristics of Sinusoidal Signals Benefits and Applications of Sinusoidal Signals Relation between Sinusoidal and Complex Exponential Signals Elementary signals DC Signal Unit Step Function Exponential Signal Sinc Function Gaussian Pulse Unit Ramp Function Signum Function Rectangular Pulse Dirac Delta or Unit Impulse Function Periodic Pulse and Impulse Trains Fourier series Orthogonal Functions Dirichlets Conditions Quadrature Fourier Series Polar Fourier Series Complex Exponential Fourier Series Spectrum of Periodic Signals Power of Periodic Signals Fourier transform Fourier Transform Pair Fourier Spectra Fourier Transform for Periodic Signals Properties of Fourier Transform Numerical Computation of Fourier Transform: Discrete Fourier Transform Time and frequency relations Bandwidth Definitions Time-Bandwidth Product Summary and Sources Probability, Random Variables, and Random Processes Introduction Contents Probability Basic Definitions Axioms of Probability Conditional Probability and Bayes’ Rule Random variables Single Random Variable Important Single Random Variables Expected Value Conditional cdf and pdf of a Random Variable Functions of a Single Random Variable Chebyshev Inequality Pair of Random Variables Independent, Uncorrelated, and Orthogonal Random Variables Jointly Gaussian Random Variables Sum of Random Variables Random processes Basic Concepts Statistical Averages Stationary Processes Ergodic Processes Power Spectral Density Response of Linear Time-Invariant Systems to Random Processes Gaussian Random Process Noise Narrowband Bandpass Noise Sampling Theorem of Random Signals Summary and Sources Problems Analog-to-Digital Conversion Introduction Sampling process Sampling Theorem Undersampling and Aliasing Effect Natural Sampling and Flat-Top Sampling Upsampling and Oversampling Sampling of Bandpass Signals and Random Signals Quantization process Uniform Quantization Nonuniform Quantization Vector Quantization Digital pulse modulation Pulse-Code Modulation PCM Differential PCM DPCM and Adaptive DPCM ADPCM Delta Modulation DM and Adaptive DM ADM Line codes Line Coding Schemes and Selection Criteria Power Spectral Density of Line Codes Summary and Sources Problems Baseband Digital Transmission Introduction Baseband binary PAM transmission system model Intersymbol interference Nyquist Criterion for Distortionless Zero-ISI Transmission Raised-Cosine Pulse Spectrum Eye Diagrams Optimum system design for noise immunity Bit Error Rate Derivation Optimum Transmitting and Receiving Filters Design Procedure and Example Baseband M-ary signaling schemes Bandwidth and Bit Rate Power and Bit Error Rate Binary vs. M-ary Signaling Schemes Equalization Viterbi Equalizers Linear Equalizers Decision-Feedback Equalizers Adaptive Equalization Summary and Sources Problems Passband Digital Transmission Introduction Optimum receiver principles System Model Gram-Schmidt Orthogonalization Procedure Geometric Representation and Interpretation of Signals Receiver Implementation Probability of Error Nonwhite Noise and Noncoherent Detection Binary digital modulation schemes Binary Amplitude-Shift Keying Binary Frequency-Shift Keying Binary Phase-Shift Keying Comparison of Binary Digital Modulation Schemes Coherent quaternary signaling schemes Quadrature Phase-Shift Keying Offset Quadrature Phase-Shift Keying Minimum-Shift Keying M-ary coherent modulation techniques M-ary Amplitude-Shift Keying M-ary Phase-Shift Keying M-ary Quadrature Amplitude Modulation M-ary Frequency-Shift Keying Comparison of M-ary Modulation Schemes Orthogonal Frequency-Division Multiplexing Summary and Sources Problems Synchronization Introduction Synchronization levels Scrambling Pseudorandom Scrambler Self-Synchronizing Scrambler Phase-Locked Loop PLL Basic Operation Linear Model of PLL Carrier Recovery The Mth-Power Loop The Costas Loop Symbol Synchronization Nonlinear-Filter Synchronizer Early-Late Gate Synchronizer Summary and Sources Problems Information Theory Introduction Measure of information Information Content Average Information Content Extended DMS Classification of source codes Block Codes Fixed-Length Codes Variable-Length Codes Distinct Codes Prefix-Free Instantaneous Codes Uniquely Decodable Codes Kraft Inequality Extension Codes Source Coding theorem Lossless data compression Huffman Source Coding Algorithm Lempel-Ziv Source Coding Algorithm Discrete Memoryless channels Channel Transition Probabilities Mutual Information Capacity of Discrete Memory Channel Channel coding theorem Gaussian Channel Capacity Theorem Summary and Sources Problems Error-Control Coding Introduction Errors Types of Errors Methods of Controlling Errors Classes of Codes Decoding Methods Error-detection methods Parity-Check Codes Checksum Cyclic Redundancy Check Automatic Repeat Request ARQ Stop-and-Wait, Go-Back-N, and Selective-Repeat ARQ Techniques Performance of ARQ Systems Block codes Description and Capabilities of Linear Block Codes Syndrome-Based Decoding Well-Known Codes Convolutional codes Representations of Convolutional Codes Maximum-Likelihood Decoding: The Viterbi Algorithm Trellis-Coded Modulation Compound codes Interleavering Simple Combining Codes Turbo Codes Low-Density Parity-Check Codes Summary and Sources Problems Communication Networks Introduction Multiplexing Frequency-Division Multiplexing Time-Division Multiplexing Wavelength-Division Multiplexing Duplexing Frequency-Division Duplexing Time-Division Duplexing Multiple Access Frequency-Division Multiple Access Time-Division Multiple Access Code-Division Multiple Access Random access ALOHA CSMA Controlled Access Reservation Polling Wired Communication Networks Circuit-Switched and Packet-Switched Networks Topology Routing and Flow Control Local Area Networks Telephone and Cable Networks Network Security and Cryptography Private-Key Cryptography Public-Key Cryptography Digital Signatures Summary and Sources Problems Wireless Communications Introduction Radio-link analysis Sources of Interference, Loss, and Noise Received Signal Power and Path Loss Noise Temperature and Receive Figure of Merit Link Margin and Link Threshold Frequency reuse Dual Polarization Spatial Separation Mobile-radio propagation characteristics Radio-Propagation Mechanisms Doppler Effect Delay Spread and Coherent Bandwidth Doppler Spread and Coherence Time Large-Scale Fading and Small-Scale Fading Fast Fading and Slow Fading Flat Fading and Frequency-Selective Fading Diversity Time Diversity Space Diversity Site Diversity Frequency Diversity Polarization Diversity Angle Diversity Path Diversity Diversity-combining methods Selection Combining Maximal-Ratio Combining Equal-Gain Combining Emerging wireless communication systems Evolution of Wireless Communication Systems 4G Systems TV White Spaces Summary and Sources Problems Analog Continuous-Wave Modulation Introduction Analog Continuous-Wave CW Modulation Amplitude moDUlation Conventional Amplitude Modulation Double-Sideband Suppressed-Carrier Amplitude Modulation Single-Sideband Amplitude Modulation Vestigial-Sideband Amplitude Modulation Frequency modUlation Representation of FM Signals Spectral Analysis of FM Signals FM Modulation and Demodulation Amplitude Nonlinearity in Analog CW Modulation Effect of Amplitude Nonlinearity on AM Systems Effect of Amplitude Nonlinearity on FM Systems Noise in analog CW modulation Effect of Noise on AM Systems Effect of Noise on FM Systems Commercial radio broadcasting AM Radio Broadcasting and Reception FM Radio Broadcasting and Reception Comparison of Analog CW Modulation Schemes Summary and Sources List of Acronyms and Abbreviations Index A B C D E F G H I J K L M N O P Q R S T U V W Z Annotation Introduction to Digital Communications is a comprehensive third- and fourth-year undergraduate-level and first-year graduate level textbook focusing exclusively on all critical elements of digital communications. Written by Ali Grami, lead researcher and principal designer of the world's first broadband access satellite system, the book demonstrates the basic principles in the analysis and design of digital communication systems in a coherent fashion, and introduces the underlying design objectives and constraints. Descriptive applications, intuitive explanations, practical examples, and technological advances in the field are hallmark features of this book, which begins by laying a solid foundation of signals and systems. The book discusses analog-to-digital & digital-to-analog conversions, since the modalities perceived by humans, such as speech, music, image and video, are all in analog and yet the transmission is in digital. The text also fully describes digital baseband transmission and modulation techniques, source coding (e.g., digital compression) to reduce transmission rate and storage requirements, and channel coding (e.g., digital error control) to improve performance, highlighting major aspects of multi-user communications and providing a complete chapter on digital communication applications. The first and only undergraduate textbook to provide comprehensive and detailed coverage of all major topics in digital communications, including source and channel coding techniquesProvides clear descriptions and intuitive explanations of all theoretical and complex concepts, with an emphasis on not only what and how, but also on whyIncludes significant discussions on design objectives and valuable insight into design constraints, along with their imperative trade-offsContains numerous descriptive applications and practical examples throughout Introduction to Digital Communications explores the basic principles in the analysis and design of digital communication systems, including design objectives, constraints and trade-offs. After portraying the big picture and laying the background material, this book lucidly progresses to a comprehensive and detailed discussion of all critical elements and key functions in digital communications. The first undergraduate-level textbook exclusively on digital communications, with a complete coverage of source and channel coding, modulation, and synchronization. Discusses major aspects of communication networks and multiuser communications Provides insightful descriptions and intuitive explanations of all complex concepts Focuses on practical applications and illustrative examples. A companion Web site includes solutions to end-of-chapter problems and computer exercises, lecture slides, and figures and tables from the text.