i Syllabus osmania university UNIT - I CHAPTER - 1 : INTRODUCTION TO Elements of Digital Communication System, Comparison of Digital and Analog Communication Systems. CHAPTER - 2 : DIGITAL TRANSMISSION OF ANALOG SIGNALS Analog to Digital Conversion, Quantization and Encoding Techniques, PCM, Companding in PCM Systems μ-law and A-law, Applications of PCM : PCM-TDM, Introduction to Linear Prediction Theory, Modulation and Demodulation of DPCM and DM, Quantization Noise and Slope Overload Error in DM, Modulation and Demodulation of ADM, Comparison of PCM, DPCM, DM and ADM, SNR of PCM and DM, Vocoders. UNIT - II CHAPTER - 3 : INFORMATION THEORY Uncertainty, Information and entropy, Source Coding, Shannon Fano Algorithm and Huffman Coding, Discrete Memoryless Channels, Probability Relations in a Channel, Priori and Posteriori Entropies, Cascaded Channels, Mutual Information, Channel Capacity, Information Rate and Information Capacity, Rate Distortion. UNIT - III CHAPTER - 4 : ERROR CONTROL CODING Types of Transmission Errors, Need for Error Control Coding, Linear Block Codes (LBC), Description of LBC, Generation, Syndrome and Error Detection, Minimum Distance of a Block Code, Error Correcting and Error Detecting Capabilities, Standard Array and Syndrome Decoding, Hamming Codes, Binary Cyclic Codes (BCC), Description of Cyclic Codes, Encoding, Decoding and Error Correction of Cyclic Codes Using Shift Registers, BCH Codes, Convolution Codes, Description, Encoding and Decoding.
ii UNIT - IV CHAPTER - 5 : BASE BAND DATA A TRANSMISSION Base Band Data Transmission, Error Probability, Matched Filter, Correlation Receiver. CHAPTER - 6 : DIGITAL CARRIER MODULATION SCHEMS Coherent and Non Coherent ASK, FSK, PSK, DPSK, and QPSK, and Error Probability, Need for MSK Modulation, Comparison of Digital Carrier Modulation Schemes, M ary Signaling Schemes, Synchronization Methods. UNIT - V CHAPTER - 7 : SPREAD SPECTRUM MODULATION Need for Spreading Code, Generation and Characteristics of PN Sequences, Direct Sequence Spread Spectrum and Frequency Hopping Spread Spectrum Systems and Their Applications, Acquisition Schemes for Spread Spectrum Receivers, Tracking of FH and DS Signals.
iii digital communication FOR (B.E OSMANIA) III YEAR II SEMESTER (ELECTRONIC AND COMMUNICATION ENGINEERING) UNIT - I [CH. H. - 1] ] [INTRODUCTION TO ]... 1.1-1.10 1.1 INTRODUCTION... 1.2 1.2 ELEMENTS OF DIGITAL AL COMMUNICATION SYSTEM... 1.3 1.2.1 Information Source... 1.4 1.2.2 Source Encoder/Decoder... 1.5 1.2.3 Communication Channel... 1.6 1.2.4 Modulator... 1.7 1.2.5 Demodulator... 1.8 1.2.6 Channel Encoder/Decoder... 1.8 1.2.7 Other Functional Blocks... 1.9 1.3 COMPARISON OF DIGITAL AL AND ANALOG COMMUNICATION SYSTEMS... 1.9 UNIT - II [CH. - 2] ] [DIGITAL TRANSMISSION OF ANALOG SIGNALS]... 1.11-1.78 2.1 ANALOG TO DIGITAL CONVERSION... 1.12 2.2 PULSE CODE MODULATION (PCM)... 1.14 2.2.1 Sampling... 1.15 2.2.2 Quantization... 1.15 2.2.2.1 Uniform Quantization... 1.17 2.2.2.2 Non Uniform Quantization... 1.18
iv 2.2.2.3 Companding in PCM Systems : m-law and A-Law... 1.20 2.2.2.3.1 μ-law Companding... 1.22 2.2.2.3.2 A-Law Companding... 1.23 2.2.2.3.3 Companding Gain... 1.24 2.2.3 Encoding... 1.24 2.2.3.1 Electrical Representation of Binary Data... 1.26 2.2.3.2 Differential Encoding... 1.28 2.2.3.3 Desirable Properties of Line Coding... 1.28 2.2.4 Regeneration... 1.29 2.2.5 Decoding... 1.30 2.2.6 Reconstruction... 1.30 2.2.7 Noise in PCM Systems... 1.31 2.2.7.1 Quantization Noise... 1.31 2.2.8 SNR of PCM... 1.33 2.2.9 Transmission Bandwidth in PCM... 1.34 2.2.10 Advantages / Disadvantages of Limitation of PCM... 1.35 2.3 APPLICATIONS OF PCM : PCM TDM... 1.36 2.3.1 Synchronous TDM-PCM System... 1.36 2.3.2 Asynchronous TDM : Pulse Stuffing... 1.38 2.4 INTRODUCTION TO O LINEAR PREDICTION THEORY... 1.38 2.5 DIFFERENTIAL PULSE CODE MODULATION (DPCM)... 1.39 2.5.1 DPCM Transmitter/Modulation of DPCM Wave... 1.40 2.5.2 DPCM Receiver / Demodulation of DPCM Wave... 1.41 2.5.3 Advantages and Disadvantages of DPCM... 1.42 2.6 DELTA MODULATION... 1.42 2.6.1 DM Transmitter/Modulation of DM Wave... 1.43 2.6.2 DM Receiver / Demodulation of DM Wave... 1.45
v 2.6.3 Slope Overload Error and Granular Noise in DM... 1.46 2.6.3.1 Slope Overload Error... 1.46 2.6.3.2 Granular Noise... 1.47 2.6.4 Quantization Noise in Delta Modulation... 1.48 2.6.5 Signal to Quantization Noise Ratio (SNR) of DM... 1.49 2.6.6 Advantages of Delta Modulation... 1.51 2.6.7 Disadvantages of Delta Modulation... 1.51 2.6.8 Bit Rate (or Signaling Rate) of a DM System... 1.51 2.7 ADAPTIVE APTIVE DELTA MODULATION (ADM)... 1.52 2.7.1 Step Size Adjustment : Adaptive Algorithm... 1.52 2.7.2 ADM Transmitter... 1.54 2.7.3 ADM Receiver... 1.54 2.7.4 Advantages of ADM... 1.55 2.8 COMPARISON OF PCM, DPCM, DM AND ADM... 1.55 2.9 VOCODERS... 1.56 2.9.1 Channel Vocoder... 1.56 2.9.2 Formant Vocoder... 1.59 2.9.3 Linear Predictor Coders... 1.59 2.10 SOLVED PROBLEMS... 1.61 SHORT QUESTIONS AND ANSWERS NSWERS... 1.72-1.78 UNIT - III [CH. - 3] ] [INFORMATION THEORY]... 2.1-2.80 3.1 INTRODUCTION TO INFORMATION THEORY... 2.2 3.2 INFORMATION SOURCE... 2.2 3.3 UNCERTAINTY... 2.3 3.4 MEASURE OF INFORMATION TION... 2.3 3.4.1 Units of Information... 2.4 3.4.2 Properties of Measure of Information... 2.4
vi 3.5 ENTROPY... 2.8 3.5.1 Properties of Entropy... 2.9 3.5.2 Entropy of a Binary Memoryless Source... 2.10 3.6 INFORMATION RATE TE... 2.16 3.7 MARGINAL, JOINT AND CONDITIONAL ENTROPIES... 2.17 3.7.1 Marginal Entropies... 2.18 3.7.2 Joint Entropy... 2.18 3.7.3 Conditional Entropy... 2.19 3.7.4 Interpretations of Entropies in a Communications System... 2.19 3.7.5 Relation Between Joint and Conditional Entropies... 2.19 3.8 PRIORI AND POSTERIORI ENTROPIES... 2.21 3.9 MUTUAL AL INFORMATION... 2.21 3.9.1 Relation Between Mutual Information, Channel Input, Output Entropies and Conditional Entropy... 2.22 3.9.2 Properties of Mutual Information... 2.23 3.9.3 Guidelines to Find the Mutual Information... 2.25 3.10 SOURCE CODING... 2.27 3.10.1 Terminology Associated with Coding... 2.27 3.10.2 Coding Length... 2.28 3.10.3 Coding Efficiency... 2.28 3.10.4 Source Coding Theorem : Shannon s First Theorem... 2.28 3.10.5 Shannon Fano Algorithm... 2.31 3.10.6 Huffman Coding... 2.34 3.10.6.1 Limitations of Huffman Coding... 2.38 3.11 DISCRETE MEMORY CHANNELS... 2.38 3.11.1 Probability Relations in a Channel... 2.39
vii 3.12 TYPES OF CHANNELS... 2.40 3.12.1 Lossless Channels... 2.40 3.12.2 Deterministic Channel... 2.40 3.12.3 Noiseless Channels... 2.41 3.12.4 Symmetric Channel... 2.41 3.12.5 Binary Symmetric Channel... 2.42 3.12.6 Cascaded Channels... 2.44 3.13 CHANNEL CAPACITY CITY... 2.46 3.13.1 Channel Efficiency... 2.47 3.13.2 Channel Redundancy... 2.47 3.13.3 Channel Coding... 2.47 3.13.4 Channel Coding Theorem : Shannon s s Second Theorem... 2.47 3.13.5 Channel Capacities of Various Channels... 2.48 3.14 INFORMATION (OR) CHANNEL CAPACITY CITY THEOREM : SHANNON S THIRD THEOREM... 2.54 3.15 RATE TE DISTOR ORTION... 2.56 3.16 SOLVED PROBLEMS... 2.58 SHORT QUESTIONS AND ANSWERS NSWERS... 2.77-2.80 UNIT - III [CH. - 4] ] [ERROR [ CONTROL CODING]... 3.1-3.72 4.1 INTRODUCTION TO O ERROR CONTROL CODING... 3.2 4.1.1 Need for Error Control Coding... 3.2 4.1.2 Methods of Controlling Errors... 3.3 4.1.3 Types of Transmission Errors... 3.4 4.1.4 Types of Codes... 3.4 4.1.5 Some Important Terminology Related to Error Control Coding... 3.4
viii 4.2 LINEAR BLOCK CODES (LBC)... 3.5 4.2.1 Matrix Description of Linear Block Codes... 3.6 4.2.2 Generation of Linear Block Codes... 3.7 4.2.3 Syndrome and Error Detection... 3.11 4.2.3.1 Properties of Syndrome... 3.14 4.2.4 Minimum Distance of a Block Code... 3.18 4.2.5 Error Correcting and Error Detecting Capabilities of LBC... 3.19 4.2.6 Standard Array and Syndrome Decoding... 3.21 4.2.6.1 Standard Arrays... 3.21 4.2.6.2 Syndrome Decoding using Standard Array... 3.24 4.2.6.3 Implementation of Syndrome Decoding of an (n, k) Linear Code... 3.28 4.2.7 Hamming Codes... 3.30 4.2.7.1 Error Detection and Correction Capabilities of Hamming Code... 3.30 4.2.7.2 Generator and Parity Check Matrix for a Hamming Code... 3.31 4.3 BINARY CYCLIC CODES (BCC)... 3.31 4.3.1 Description (Algebraic Structure) of Cyclic Codes... 3.32 4.3.1.1 Generation of Code Vectors in Non-Systematic Form... 3.32 4.3.1.2 Generation of Code Vectors in Systematic Form... 3.34 4.3.2 Encoding of Cyclic Codes Using Shift Registers... 3.36 4.3.3 Decoding, Error Detection and Error Correction of Cyclic Codes Using Shift Registers... 3.38 4.3.3.1 Syndrome Decoding of Cyclic Codes... 3.38 4.3.3.2 Block Diagram of Syndrome Calculator... 3.40
ix 4.3.3.3 Error Detection... 3.42 4.3.3.4 Error Correction / General Block Diagram of Decoder For Cyclic Codes... 3.42 4.3.4 Advantages and Disadvantages of Cyclic Codes... 3.43 4.4 BOSE CODES (BOSE - CHAUDHRI - HOCQUENGHEM CODES)... 3.43 4.5 CONVOLUTIONAL CODES... 3.45 4.5.1 Convolutional Encoder... 3.45 4.5.1.1 An Example of Convolutional Encoder... 3.46 4.5.1.2 Time Domain Approach to Analysis of Convolutional Encoder... 3.47 4.5.1.3 Transform Domain Approach to Analysis of Convolutional Encoder... 3.48 4.5.2 Representation of Convolution Encoder... 3.51 4.5.2.1 Code Tree ree... 3.52 4.5.2.2 Trellis Diagram... 3.54 4.5.2.3 State Diagram... 3.55 4.5.3 Decoding Methods of Convolutional Codes... 3.55 4.5.3.1 Viterbi Algorithm... 3.55 4.5.3.2 Sequential Decoding for Convolutional Codes... 3.59 4.5.4 Comparison of Block Codes and Convolutional Codes... 3.61 4.6 SOLVED PROBLEMS... 3.62 SHORT QUESTIONS AND ANSWERS NSWERS... 3.68-3.72 UNIT - IV [CH. - 5] ] [BASE BAND DATA TRANSMISSION]... 4.1-4.16 5.1 INTRODUCTION... 4.2 5.2 BASEBAND TRANSMISSION OF BINARY DATA A (PAM SYSTEMS)... 4.2 5.3 Intersymbol Interference (ISI)... 4.4 5.3.1 Nyquist Criterion for Zero ISI... 4.7
x 5.3.2 Ideal Solution or Nyquist Solution for Zero ISI... 4.7 5.3.3 Practical Solution : Raised Cosine Spectrum... 4.10 5.3.4 Transmission Bandwidth Requirement (Raised Cosine Filter)... 4.13 5.4 EYE PATTERN... 4.14 UNIT - IV [CH. H. - 6] ] [DIGITAL CARRIER MODULATION SCHEMES]... 4.17-4.96 6.1 INTRODUCTION TO BANDPASS ASS TRANSMISSION... 4.18 6.2 TYPES OF DIGITAL MODULATION TECHNIQUES... 4.19 6.3 BANDPASS ASS BINARY DATA A TRANSMISSION SYSTEM... 4.20 6.3.1 The Optimum Filter... 4.22 6.3.1.1 Expression for Probability of Error... 4.22 6.3.1.2 Transfer Function of the Optimum Filter ilter... 4.24 6.3.2 Matched Filter... 4.26 6.3.2.1 Impulse Response for the Matched Filter... 4.26 6.3.2.2 Expression of Probability of Error for a Matched Filter... 4.27 6.3.3 Correlation Receiver (Integration and Dump Filter)... 4.28 6.4 AMPLITUDE SHIFT KEYING (AK)... 4.31 6.4.1 Generation/Modulation of ASK Signal... 4.33 6.4.2 Coherent Detection of ASK... 4.33 6.4.3 Probability of Error in ASK... 4.34 6.4.4 Non Coherent ASK... 4.35 6.4.5 Power Spectral Density of ASK Signal... 4.38 6.5 FREQUENCY SHIFT KEYING (FSK)... 4.39 6.5.1 Generation of BFSK Signal... 4.40 6.5.2 Coherent Detection of BFSK Signal... 4.41 6.5.3 Non-Coherent Detection of BFSK Signal... 4.42
xi 6.5.4 Probability of Error in FSK... 4.42 6.5.5 Power Spectral Density of BFSK Signal... 4.44 6.5.6 Bandwidth of BFSK Signal... 4.46 6.6 PHASE SHIFT KEYING (PSK)... 4.46 6.6.1 Generation / Modulation of BPSK Signal... 4.48 6.6.2 Coherent Detection of PSK... 4.48 6.6.3 Probability of Error... 4.49 6.6.4 Power Spectral Density of BPSK Signal... 4.51 6.6.5 Bandwidth of BPSK Signal... 4.53 6.7 DIFFERENTIAL PHASE SHIFT KEYING (DPSK)... 4.53 6.7.1 Generation / Modulation of DPSK Signals... 4.53 6.7.2 Coherent Detection of DPSK... 4.55 6.7.3 Probability of Error in DPSK... 4.56 6.7.4 Bandwidth of DPSK Signal... 4.56 6.7.5 Advantages of DPSK... 4.57 6.7.6 Disadvantages of DPSK... 4.57 6.8 QUADRA ADRATURE PHASE SHIFT KEYING (QPSK)... 4.57 6.8.1 Generation / Modulation of QPSK for (QPSK Modulator... 4.57 6.8.2 QPSK Demodulation (Coherent Detection of QPSK Wave)... 4.61 6.8.3 Probability of Error in QPSK... 463 6.8.4 PSD of QPSK Signals... 4.64 6.8.5 Bandwidth of QPSK Signal... 4.65 6.8.6 Advantages of QPSK... 4.65 6.9 NEED FOR MSK MODULATION... 4.65 6.9.1 Phase Continuity in MSK... 4.70 6.9.2 Generation of MSK Signal (MSK Modulation)... 4.72
xii 6.9.3 Detection of MSK Wave (MSK Demodulation)... 4.72 6.9.4 Power Spectral Density of MSK... 4.73 6.9.5 Bandwidth of MSK... 4.74 6.9.6 Advantages of MSK as Compared to QPSK... 4.74 6.9.7 Drawbacks of MSK... 4.74 6.10 COMPARISON OF DIGITAL CARRIER MODULATION SCHEMES... 4.75 6.11 M-ARY SIGNALING SCHEMES... 4.76 6.11.1 M-Ary PSK... 4.76 6.11.1.1 Generation of M-ary PSK... 4.76 6.11.1.2 Detection of M-ary PSK... 4.77 6.11.1.3 Signal Space Diagram of M-ary PSK Signal... 4.78 6.11.1.4 Power Spectral Density of M-ary PSK... 4.79 6.11.1.5 Bandwidth of M-ary PSK... 4.80 6.11.2 M-Ary FSK... 4.80 6.11.2.1 Generation of M-ary FSK Signal... 4.80 6.11.2.2 Detection of M-ary FSK Signal... 4.81 6.11.2.3 Signal Space Diagram of M-ary FSK... 4.81 6.11.2.4 Power Special Density of M-ary FSK... 4.83 6.11.2.5 Bandwidth of M-ary FSK... 4.83 6.11.3 Quadrature Amplitude Shift Keying (QASK)... 4.84 6.11.3.1 Signal Space Diagram fo QASK Signal... 4.84 6.11.3.2 Generation of QASK... 4.85 6.11.3.3 Detection of QASK Signal... 4.86 6.11.3.4 Power Spectral Density of QASK Signal... 4.87 6.12 SYNCHRONIZATION METHODS... 4.88 6.12.1 Carrier Synchronization... 4.89 6.12.2 Symbol Synchronization... 4.90 SHORT QUESTIONS AND ANSWERS NSWERS... 4.92-4.96
xiii UNIT - V [CH. H. - 7] ] [SPREAD SPECTRUM MODULATION]... 5.1-5.50 7.1 INTRODUCTION TO SPREAD SPECTRUM MODULATION... 5.2 7.1.1 Definition of Spread Spectrum... 5.2 7.1.2 Need for Spreading Code... 5.2 7.1.3 Advantages of Spread Spectrum Communication System... 5.3 7.1.4 Applications of Spread Spectrum... 5.3 7.1.5 Classification of Spread Spectrum Systems... 5.4 7.2 GENERATION AND CHARACTERISTICS CTERISTICS OF PN SEQUENCE... 5.4 7.2.1 Definition of PN Sequence... 5.4 7.2.2 Generation of PN Sequences... 5.5 7.2.3 CHARACTERISTICS/PROPERTIES OF MAXIMUM LENGTH PN SEQUENCE... 5.8 7.2.3.1 Balance Property... 5.8 7.2.3.2 Run Property... 5.8 7.2.3.3 Correlation Property... 5.9 7.2.4 Selection of Maximum Length Sequence... 5.11 7.3 DIRECT SEQUENCE SPREAD SPECTRUM (DSSS)... 5.12 7.3.1 Baseband Direct Sequence Spread Spectrum System... 5.12 7.3.2 DSSS With Coherent BPSK... 5.15 7.3.3 Performance of DS SS System... 5.16 7.3.3.1 Signal-to-Noise Ratio... 5.16 7.3.3.2 Processing Gain... 5.16 7.3.3.3 Probability of Error of DS/BPSK System... 5.16 7.3.3.4 Jamming Margin (Antijam Characteristics)... 5.17 7.3.4 Advantages and Disadvantages of DS Spread Systems... 5.19 7.4 FREQUENCY HOP SPREAD SPECTRUM... 5.19 7.4.1 Slow Frequency Hopping... 5.20 7.4.1.1 Transmitter of FH/MFSK... 5.20
xiv 7.4.1.2 Receiver of FH/MFSK... 5.21 7.4.1.3 Performance of Slow Frequency Hopping... 5.22 7.4.1.4 An Example Illustrating Slow Frequency Hopping... 5.24 7.4.2 Fast Frequency Hopping... 5.26 7.4.3 Comparison of Slow and Fast Frequency Hopping... 5.28 7.4.4 Advantages and Disadvantages of FH-SS Systems... 5.28 7.5 COMPARISON OF DS AND FH SPREAD SPECTRUM SYSTEMS... 5.29 7.6 APPLICATIONS OF SPREAD SPECTRUM SYSTEMS... 5.30 7.6.1 Code Division Multiple Access... 5.30 7.6.2 Multipath Suppression... 5.30 7.6.3 Range Determination using DS-SS... 5.31 7.7 SYNCHRONIZATION OF SPREAD SPECTRUM SYSTEMS... 5.33 7.7.1 Acquisition Schemes for Spread Spectrum Receivers... 5.33 7.7.1.1 Acquisition of FH Signal... 5.33 7.7.1.2 Acquisition of DS Signal... 5.35 7.7.2 Tracking of FH and SS Signals... 5.37 7.7.2.1 Tracking /Fine ine Synchronization of FH Signal... 5.37 7.7.2.2 Tracking (or) Fine Synchronization of DS Signal... 5.38 7.8 SOLVED PROBLEMS... 5.39 SHORT QUESTIONS AND ANSWERS NSWERS... 5.44-5.50 EXPECTED UNIVERSITY QUESTIONS Expected University Questions with Solutions... E.1 - E.10