Digital communications : : fundamentals and applications

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Cover Page About This eBook Title Page Copyright Page Dedication Page Contents at a Glance Contents Preface Organization of the Book Additional Book Resources Acknowledgments About the Authors Chapter 1. Signals and Spectra 1.1 Digital Communication Signal Processing 1.2 Classification of Signals 1.3 Spectral Density 1.4 Autocorrelation 1.5 Random Signals 1.6 Signal Transmission Through Linear Systems 1.7 Bandwidth of Digital Data 1.8 Conclusion References Problems Questions Chapter 2. Formatting and Baseband Modulation 2.1 Baseband Systems 2.2 Formatting Textual Data (Character Coding) 2.3 Messages, Characters, and Symbols 2.4 Formatting Analog Information 2.5 Sources of Corruption 2.6 Pulse Code Modulation 2.7 Uniform and Nonuniform Quantization 2.8 Baseband Transmission 2.9 Correlative Coding 2.10 Conclusion References Problems Questions Chapter 3. Baseband Demodulation/Detection 3.1 Signals and Noise 3.2 Detection of Binary Signals in Gaussian Noise 3.3 Intersymbol Interference 3.4 Equalization 3.5 Conclusion References Problems Questions Chapter 4. Bandpass Modulation and Demodulation/Detection 4.1 Why Modulate? 4.2 Digital Bandpass Modulation Techniques 4.3 Detection of Signals in Gaussian Noise 4.4 Coherent Detection 4.5 Noncoherent Detection 4.6 Complex Envelope 4.7 Error Performance for Binary Systems 4.8 M-ary Signaling and Performance 4.9 Symbol Error Performance for M-ary Systems (M>2) 4.10 Conclusion References Problems Questions Chapter 5. Communications Link Analysis 5.1 What the System Link Budget Tells the System Engineer 5.2 The Channel 5.3 Received Signal Power and Noise Power 5.4 Link Budget Analysis 5.5 Noise Figure, Noise Temperature, and System Temperature 5.6 Sample Link Analysis 5.7 Satellite Repeaters 5.8 System Trade-Offs 5.9 Conclusion References Problems Questions Chapter 6. Channel Coding: Part 1: Waveform Codes and Block Codes 6.1 Waveform Coding and Structured Sequences 6.2 Types of Error Control 6.3 Structured Sequences 6.4 Linear Block Codes 6.5 Error-Detecting and Error-Correcting Capability 6.6 Usefulness of the Standard Array 6.7 Cyclic Codes 6.8 Well-Known Block Codes 6.9 Conclusion References Problems Questions Chapter 7. Channel Coding: Part 2: Convolutional Codes and Reed–Solomon Codes 7.1 Convolutional Encoding 7.2 Convolutional Encoder Representation 7.3 Formulation of the Convolutional Decoding Problem 7.4 Properties of Convolutional Codes 7.5 Other Convolutional Decoding Algorithms 7.6 Reed–Solomon Codes 7.7 Interleaving and Concatenated Codes 7.8 Coding and Interleaving Applied to the Compact Disc Digital Audio System 7.9 Conclusion References Problems Questions Chapter 8. Channel Coding: Part 3: Turbo Codes and Low-Density Parity Check (LDPC) Codes 8.1 Turbo Codes 8.2 Low-Density Parity Check (LDPC) Codes Appendix 8A: The Sum of Log-Likelihood Ratios Appendix 8B: Using Bayes’ Theorem to Simplify the Bit Conditional Probability Appendix 8C: Probability that a Binary Sequence Contains an Even Number of Ones Appendix 8D: Simplified Expression for the Hyperbolic Tangent of the Natural Log of a Ratio of Binary Probabilities Appendix 8E: Proof that ϕ(x) = ϕ–1(x) Appendix 8F: Bit Probability Initialization References Problems Questions Chapter 9. Modulation and Coding Trade-Offs 9.1 Goals of the Communication System Designer 9.2 Error-Probability Plane 9.3 Nyquist Minimum Bandwidth 9.4 Shannon–Hartley Capacity Theorem 9.5 Bandwidth-Efficiency Plane 9.6 Modulation and Coding Trade-Offs 9.7 Defining, Designing, and Evaluating Digital Communication Systems 9.8 Bandwidth-Efficient Modulation 9.9 Trellis-Coded Modulation 9.10 Conclusion References Problems Questions Chapter 10. Synchronization 10.1 Receiver Synchronization 10.2 Synchronous Demodulation 10.3 Loop Filters, Control Circuits, and Acquisition 10.4 Phase-Locked Loop Timing Recovery 10.5 Frequency Recovery Using a Frequency-Locked Loop (FLL) 10.6 Effects of Phase and Frequency Offsets 10.7 Conclusion References Problems Questions Chapter 11. Multiplexing and Multiple Access 11.1 Allocation of the Communications Resource 11.2 Multiple-Access Communications System and Architecture 11.3 Access Algorithms 11.4 Multiple-Access Techniques Employed with INTELSAT 11.5 Multiple-Access Techniques for Local Area Networks 11.6 Conclusion References Problems Questions Chapter 12. Spread-Spectrum Techniques 12.1 Spread-Spectrum Overview 12.2 Pseudonoise Sequences 12.3 Direct-Sequence Spread-Spectrum Systems 12.4 Frequency-Hopping Systems 12.5 Synchronization 12.6 Jamming Considerations 12.7 Commercial Applications 12.8 Cellular Systems 12.9 Conclusion References Problems Questions Chapter 13. Source Coding 13.1 Sources 13.2 Amplitude Quantizing 13.3 Pulse Code Modulation 13.4 Adaptive Prediction 13.5 Block Coding 13.6 Transform Coding 13.7 Source Coding for Digital Data 13.8 Examples of Source Coding 13.9 Conclusion References Problems Questions Chapter 14. Fading Channels 14.1 The Challenge of Communicating over Fading Channels 14.2 Characterizing Mobile-Radio Propagation 14.3 Signal Time Spreading 14.4 Time Variance of the Channel Caused by Motion 14.5 Mitigating the Degradation Effects of Fading 14.6 Summary of the Key Parameters Characterizing Fading Channels 14.7 Applications: Mitigating the Effects of Frequency-Selective Fading 14.8 Conclusion References Problems Questions Chapter 15. The ABCs of OFDM (Orthogonal Frequency-Division Multiplexing) 15.1 What Is OFDM? 15.2 Why OFDM? 15.3 Getting Started with OFDM 15.4 Our Wish List (Preference for Flat Fading and Slow Fading) 15.5 Conventional Multi-Channel FDM versus Multi-Channel OFDM 15.6 The History of the Cyclic Prefix (CP) 15.7 OFDM System Block Diagram 15.8 Zooming in on the IDFT 15.9 An Example of OFDM Waveform Synthesis 15.10 Summarizing OFDM Waveform Synthesis 15.11 Data Constellation Points Distributed over the Subcarrier Indexes 15.12 Hermitian Symmetry 15.13 How Many Subcarriers Are Needed? 15.14 The Importance of the Cyclic Prefix (CP) in OFDM 15.15 An Early OFDM Application: Wi-Fi Standard 802.11a 15.16 Cyclic Prefix (CP) and Tone Spacing 15.17 Long-Term Evolution (LTE) Use of OFDM 15.18 Drawbacks of OFDM 15.19 Single-Carrier OFDM (SC-OFDM) for Improved PAPR Over Standard OFDM 15.20 Conclusion References Problems Questions Chapter 16. The Magic of MIMO (Multiple Input/Multiple Output) 16.1 What is MIMO? 16.2 Various Benefits of Multiple Antennas 16.3 Spatial Multiplexing 16.4 Capacity Performance 16.5 Transmitter Channel-State Information (CSI) 16.6 Space-Time Coding 16.7 MIMO Trade-Offs 16.8 Multi-User MIMO (MU-MIMO) 16.9 Conclusion References Problems Questions Index Chapter 17. Encryption and Decryption 17.1 Models, Goals, and Early Cipher Systems 17.2 The Secrecy of a Cipher System 17.3 Practical Security 17.4 Stream Encryption 17.5 Public Key Cryptosystems 17.6 Pretty Good Privacy 17.7 Conclusion References Problems Questions Appendix A. A Review of Fourier Techniques A.1 Signals, Spectra, and Linear Systems A.2 Fourier Techniques for Linear System Analysis A.3 Fourier Transform Properties A.4 Useful Functions A.5 Convolution A.6 Tables of Fourier Transforms and Operations A.7 sampled data fourier transform References Appendix B. Fundamentals of Statistical Decision Theory B.1 Bayes’ Theorem B.2 Decision Theory B.3 Signal Detection Example References Appendix C. Response of a Correlator to White Noise Appendix D. Often-Used Identities Appendix E. S-Domain, Z-Domain, and Digital Filtering E.1 The Laplace Transform E.2 The z-transform E.3 Digital Filtering E.4 Finite Impulse Response Filter Design E.5 Infinite Impulse Response Filter Design References Appendix F. OFDM Symbol Formation with an N-Point Inverse Discrete Fourier Transform (IDFT) Appendix G. List of Symbols