Digital Communication 1. INTRODUCTION
1.1 INTRODUCTION
1.2 TYPICAL DIGITAL COMMUNICATION SYSTEM
1.3 ADVANTAGES OF DIGITAL COMMUNICATION
1.3.1 Regeneration of digital signals
1.3.2 Power efficiency of digital modulators
1.3.3 Bandwidth compression
1.3.4 Multimedia: unification of signals
1.3.5 Performance
1.3.6 Technology
2. COMMUNICATION SIGNALS AND SYSTEMS
2.1 INTRODUCTION
2.2 TIME AND FREQUENCY REPRESENTATION
2.1.1 Fourier Series
2.1.2 Fourier Transform
2.1.3 Discrete-Time Fourier Transform
2.1.4 Discrete Fourier Transform
2.3 CONVOLUTION
2.4 CORRELATION
2.5 HILBERT TRANSFORM
2.6 BANDPASS AND LOWPASS REPRESENTATIONS
2.6.1 Bandpass Signals and Systems
2.6.2 Analytic Signal
2.6.3 Lowpass Equivalent Signals
2.7 SIGNAL SPACE REPRESENTATIONS
2.7.1 Vector Space
2.7.2 Signal Space
2.7.3 Orthonormal Representation of Signals
2.7.4 Gram-Schmidt Procedure
Summary
Review Questions
Problems
3. PROBABILITY AND RANDOM PROCESSES
3.1 INTRODUCTION
3.2 PROBABILITY
3.2.1 Set Theory
3.2.2 Probability space
3.2.3 Properties of probability
3.2.4 Probability of joint events
3.2.5 Conditional probability
3.2.6 Bayes' Rule
3.2.7 Independence
3.3 RANDOM VARIABLES
3.3.1 Probability Distribution Function
3.3.2 Probability Density Function
3.3.3 Probability Mass Function
3.3.4 Mean and Variance
3.3.5 Some common distributions
3.3.6 Functions of Random Variables
3.3.7 Multiple Random Variables
3.3.8 Sum of Random Variables
3.3.9 Central Limit Theorem
3.3.10 Linear Mean Square Estimation
3.4 RANDOM PROCESSES
3.4.1 Properties of Random Processes
3.4.2 Some examples of Random Processes
Summary
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Problems
4. INFORMATION THEORY
4.1 INTRODUCTION
4.2 INFORMATION MEASURE
4.2.1 Self-Information
4.2.2 Entropy
4.2.3 Discrete Memoryless Source (DMS)
4.2.4 Joint and Conditional Entropy
4.2.5 Mutual Information
4.3 DISCRETE CHANNEL
4.3.1 Statistics of the Discrete Channel
4.3.2 Channel Capacity
4.4 CONTINUOUS RANDOM VARIABLE
4.4.1 Differential Entropy
4.4.2 Capacity of Continuous Channel
4.5 SOURCE CODING
4.5.1 Source Efficiency and Redundancy
4.5.2 Kraft inequality
4.5.3 Source coding theorem
4.5.4 Shannon-Fano Encoding
4.5.5 Huffman Coding
4.5.6 Non-binary Huffman coding
Summary
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5. DIGITAL CODING
5.1 INTRODUCTION
5.2 DIGITIZING ANALOG SIGNALS
5.2.1 Sampling
5.2.1.1 Sampling with ideal impulses
5.2.1.2 Spectra of sampled waveform
5.2.1.3 Sampling rate and aliasing noise
5.2.1.4 Sampling of bandpass signals
5.2.1.5 Sample and Hold
5.2.1.6 Spectral distortion due to Sample and Hold
5.2.2 Quantization
5.2.2.1 Quantizer characteristics
5.2.2.2 Quantization error
5.2.3 Encoding
5.2.3.1 Analog to Digital Conversion
5.2.3.2 Sigma-Delta A-D Converter
5.2.3.3 Pulse Code Modulation (PCM)
5.3 SIGNAL COMPRESSION
5.3.1 Signal Statistics and Redundancy
5.3.2 Companded PCM
5.3.2.1 A-Law Companding
5.3.2.2 m-Law Companding
5.3.2.3 Segmented companders
5.3.2.4 Performance of a PCM system
5.3.3 Predictive Coding
5.3.3.1 Delta Modulation (DM)
5.3.3.2 Adaptive Differential PCM (ADPCM)
5.3.4 Transform Coding
5.3.4.1 Discrete Cosine Transform
5.3.4.2 2-D DCT
5.3.4.3 Discrete Wavelet Transform
5.3.5 Parametric Coders
5.3.5.1 Analysis-by-synthesis coder
5.3.6 Perceptual coding
5.3.6.1 Psychoacoustics
5.3.6.2 Perceptual coder
5.4 APPLICATION OF DIGITAL CODING
5.4.1 Digital Speech
5.4.1.1 Voice Codecs and Combo Chips
5.4.2 Digital Audio
5.4.2.1 MP3 Coding
5.4.2.2 AC-3 Coding
5.4.2.3 Advanced Audio Coding (AAC)
5.4.3 Digital Video
5.4.3.1 Run-Length Coding (RLC)
5.4.3.2 Variable Length Coding
5.4.3.3 MPEG-1
5.4.3.4 MPEG-2
5.4.3.5 MPEG4
5.4.3.6 H.264
Summary
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Problems
6. MULTIPLEXING AND MULTIPLE ACCESS
6.1 INTRODUCTION
6.2 MULTIPLEXING
6.2.1 Frequency Division Multiplexing
6.2.2 Concept of Time Division Multiplexing
6.2.3 Frame Synchronization
6.2.4 Primary Multiplexing in Digital Telephony
6.2.4.1 E-1 carrier multiplex system
6.2.4.2 Signaling in E-1 carrier
6.2.4.3 Frame Synchronization in E-1 carrier
6.2.4.4 T-1 carrier multiplex system
6.2.4.5 Signaling and frame synchronization in T-1 carrier
6.2.4.6 Comparison of the primary multiplex standards
6.2.5 Higher Order Multiplexing
6.2.5.1 CEPT Plesiochronous Digital Hierarchy
6.2.5.2 North American Digital Hierarchy
6.3 MULTIPLE ACCESS
6.3.1 Frequency Division Multiple Access (FDMA)
6.3.1.1 SCPC and MCPC systems
6.3.1.2 Capacity in FDMA
6.3.1.3 Advantages and disadvantages of FDMA
6.3.1.4 Applications of FDMA
6.3.2 Time Division Multiple Access (TDMA)
6.3.2.1 TDMA Concept
6.3.2.2 TDMA Frame
6.3.2.3 Frame Efficiency
6.3.2.4 Burst Synchronization
6.3.3 Code Division Multiple Access (CDMA)
6.3.3.1 PN Sequences
6.3.3.2 Processing Gain and Capacity in CDMA
6.3.4 Random Access
6.3.4.1 Pure Aloha
6.3.4.2 Slotted Aloha (S-Aloha)
6.3.4.3 Reservation Aloha (R-Aloha)
6.3.5 Carrier Sense Multiple Access-Collision Detection (CSMA-CD)
6.3.6 Fixed Assignment and Demand Assignment Multiple Access
Summary
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Problems
7. DIGITAL MODULATION
7.1 INTRODUCTION
7.2 BASEBAND MODULATION
7.2.1 Pulse Modulation Systems
7.2.1.1 Pulse Amplitude Modulation
7.2.1.2 Pulse Width Modulation
7.2.1.3 Pulse Position Modulation
7.2.2 Baseband Signaling
7.2.2.1 Line Codes
7.2.2.2 Line Codes for PCM transmission
7.2.3 Correlative Coding
7.2.3. Inter-symbol interference (ISI)
7.2.3.2 Raised-cosine filter
7.2.3.3 Correlative Coding
7.2.3.4 Duo-binary coding
7.2.3.5 Modified duo-binary coding
7.3 BANDPASS MODULATION
7.3.1 Bandpass PAM
7.3.2 Quadrature Amplitude Modulation (QAM)
7.3.3 Digital Phase Modulation (Phase Shift Keying)
7.3.3.1 BPSK Modulation
7.3.3.2 QPSK and Offset QPSK (OQPSK)
7.3.4 Digital Frequency Modulation (Frequency Shift Keying)
7.3.4.1 FSK Generation
7.3.4.2 Continuous Phase FSK (CPFSK)
7.3.5 Minimum Shift Keying (MSK)
7.3.5.1 MSK modulator
7.3.5.2 Gaussian Minimum Shift Keying (GMSK)
7.3.5.3 Continuous Phase Modulation (CPM)
7.4 POWER SPECTRAL DENSITY
7.4.1 Power Spectral Density of Baseband Signals
7.4.1.1 Method I: Finding mpsdf from the definition
7.4.1.2 Method II: Finding mpsdf by stationarizing the signal
7.4.2 Power spectral Density of Bandpass Signals
7.4.2.1 PSD of PAM signal
7.4.2.2 PSD of a Correlative Coded Signal
7.4.2.3 PSD of BPSK signal
7.4.2.4 Bandwidth of QPSK signal
7.5 COMPARISON OF BASIC MODULATIONS
7.6 SOME SPECIAL MODULATION TECHNIQUES
7.6.1 OFDM
7.6.1.1 OFDM Concept
7.6.1.2 FFT implementation of OFDM
7.6.1.3 Applications of OFDM
7.6.2 Trellis Coded Modulation
7.6.2.1 Partitioning of Signal Space
7.6.2.2 Performance of TCM
Summary
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Problems
8. DEMODULATION AND DETECTION
8.1 INTRODUCTION
8.2 OPTIMUM RECEIVER
8.2.1 Correlation Demodulator
8.2.2 Matched Filter
8.2.3 Matched Filter Demodulator
8.3 BINARY DETECTION
8.3.1 Probability of error
8.3.2 Decision Rules
8.3.3 Sufficient Statistics
8.3.4 Performance of an optimal receiver
8.4 GENERAL BINARY DETECTION
8.4.1 Implementation of a general binary receiver
8.4.2 Performance of a general binary receiver
8.4.3 Signals with equal energy
8.4.4 Detection of Bandpass Signals
8.5 M-ARY DETECTION
8.5.1 4-PAM signal
8.5.2 Gray Coding
8.5.3 QPSK signals
8.5.4 M-ary PAM signals
8.5.5 Performance Bounds
8.6 NON COHERENT DETECTION
8.6.1 Non-coherent detection of binary signals
8.6.2 Performance of Non-coherent Receiver
8.6.3 Differential PSK
8.7 EQUALIZATION
8.7.1 Linear Transversal Filter Equalizer
8.7.2 Non-linear Equalizers
Summary
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Problems
9. ERROR CONTROL CODING
9.1 INTRODUCTION
9.1.1 Types and Measures of Error
9.1.2 Shannon-Hartley Capacity Theorem
9.1.3 Concepts behind Error Detection and Correction -A bigger picture
9.1.4 Methods of Error Control
9.1.5 Classification of Error Correcting Codes
9.2 LINEAR BLOCK CODES
9.2.1 Hamming Distance
9.2.2 Hamming Weight
9.2.3 Error Detection and Correction Capabilities of a Code
9.2.4 Codeword Error Probability Computation
9.2.5 Generator Matrix
9.2.6 Systematic Codes
9.2.7 Parity Check Matrix
9.2.8 Syndrome
9.2.9 Standard Array
9.2.10 Implementing the Decoder
9.3 CYCLIC CODES
9.3.1 Generator Polynomial for Cyclic Code
9.3.2 Systematic Cyclic Code
9.3.3 Polynomial Multiplication and Division
9.4 IMPORTANT BLOCK CODES
9.4.1 Hamming Codes
9.4.2 BCH Codes
9.4.3 Golay Codes
9.4.4 Reed-Solomon Codes
9.5 CONVOLUTIONAL CODES
9.5.1 Convolutional Encoder
9.6 CONVOLUTIONAL DECODING
9.6.1 Maximum Likelihood Decoding and Viterbi Algorithm
9.6.2 Sequential Decoding and Fano Algorithm
9.7 TURBO CODING
9.7.1 Turbo Coder
9.7.2 Turbo Decoder
9.8 LDPC
9.7 PRACTICAL APPLICATION OF ERROR CORRECTING CODES
9.7.1 Deep Space Communication
9.7.2 Satellite Communication
9.7.3 Data Transmission
9.7.4 Data Storage
9.7.5 DAB/DVB
9.7.6 Mobile and Wireless Systems
Summary
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Problems
10. SPREAD SPECTRUM COMMUNICATION
10.1 Introduction
10.2 Pseudo Noise Sequence
10.2.1 Properties of PN Sequences
10.2.2 Gold Sequences
10.3 Processing Gain and Capacity in CDMA
10.4 Direct Sequence Spread Spectrum
10.4.1 DSSS Transmitter and Receiver
10.4.2 Interference Rejection
10.4.3 Short and Long Codes
10.5 Frequency Hopping Spread Spectrum
10.5.1 FHSS Transmitter and Receiver
10.5.2 Slow and Fast Hopping
10.6 Acquisition and Synchronization
10.6.1 Parallel Acquisition
10.6.2 Sequential Acquisition
10.6.3 Sequential Acquisition with Seeding
10.7 Spread Spectrum Applications
10.7.1 Mobile Communication
10.7.2 Low Power Communication
10.7.3 Ranging
10.7.4 Multiuser Communication
Summary
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Problems
11. APPLICATIONS OF DIGITAL COMMUNICATION
11.1 INTRODUCTION
11.2 CELLULAR COMMUNICATION
11.2.1 Cellular Concept
Cochannel Interference
11.2.2 Cellular Standards
11.2.2.1 Groupe Special Mobile (GSM)
11.2.2.2
IS-95
11.2.2.3
IMT-2000
11.3 DIGITAL SATELLITE COMMUNICATIONS
11.3.1 Elements of a Satellite Communication System
11.3.2 Link analysis
11.3.2.1
Link Equation
11.3.2.2
Receiver Noise Temperature
11.3.2.3
G/T Ratio for Earth Stations
11.3.3 Multiple Access
11.3.3.1
FDMA
11.3.3.2
SPADE
11.3.3.3
Satellite TDMA
11.3.4 Special Techniques in Satellite Communication
11.3.4.1
Digital Speech Interpolation
11.3.4.2
Echo cancellation
11.3.5 Digital Satellite systems
11.3.5.1
VSAT Systems
11.3.5.2
DTH Systems
11.3.5.3
DAB Systems
11.3.5.4
Mobile Communication Systems
11.3.5.5
Search and Rescue System
11.3.5.6
Global Positioning System
11.4 OPTICAL COMMUNICATION
11.4.1 Advantages of Optical Communication
11.4.2 Signal Transmission in an Optical Fiber
11.4.2.1
Propagation by total internal reflection
11.4.2.2
Step-index and Graded-index Fibers
11.4.2.3
Numerical Aperture
11.4.2.4
Multipath Dispersion
11.4.2.5
Information Rate
11.4.3 Optical Transmission Systems
11.4.3.1
Modulation
11.3.2 Wavelength Division Multiplexing (WDM)
11.4.4 Optical Telecommunication Networks
11.4.4.1
Synchronous Optical Network (SONET)
11.4.4.2
Synchronous Digital Hierarchy (SDH)
11.4.5 Applications of Optical Fibers
11.5 WIFI AND WIMAX
Review Questions
Problems
Appendix A Useful trigonometrical identities
Appendix B Table of Q functions.
Appendix C MATLAB codes
Appendix D Laboratory manual.
Appendix E Random error generator
Appendix F Model question papers.
Appendix G Hints