DATA COMMUNICATIONS AND COMPUTER NETWORKS

Transcription

1

2 DATA COMMUNICATIONS AND COMPUTER NETWORKS Second Edition PRAKASH C. GUPTA Formerly Head Department of Information Technology Maharashtra Institute of Technology Pune Delhi

3 DATA COMMUNICATIONS AND COMPUTER NETWORKS, Second Edition Prakash C. Gupta 2014 by PHI Learning Private Limited, Delhi. All rights reserved. No part of this book may be reproduced in any form, by mimeograph or any other means, without permission in writing from the publisher. ISBN The export rights of this book are vested solely with the publisher. Eighth Printing (Second Edition) January, 2014 Published by Asoke K. Ghosh, PHI Learning Private Limited, Rimjhim House, 111, Patparganj Industrial Estate, Delhi and Printed by Rajkamal Electric Press, Plot No. 2, Phase IV, HSIDC, Kundli , Sonepat, Haryana.

4 Contents Preface xxv 1 Data Communication Concepts and Terminology Basic Model of Data Communication System Data Representation ASCII American Standard Code for Information Interchange Byte Data Transmission Parallel Transmission Serial Transmission Bit Rate Receiving Data Bits Modes of Data Transmission Asynchronous Transmission Synchronous Transmission Digital Signal Encoding Unipolar and Polar Line Codes Non Return to Zero (NRZ) Codes Return to Zero (RZ) Codes Bipolar Line Codes Alternate Mark Inversion (AMI) High Density Bipolar-3 Zeroes (HDB3) Bipolar with 8 Zeroes Substitution (B8ZS) Code Block Codes Frequency Spectrum Fourier Series Transmission Channel Bauds Baseband Transmission Modem Data Compression Information Entropy Redundancy Encoding for Compression Shannon-Fano Code Huffman Code 26 iii

5 iv CONTENTS 1.12 Data Communication Synchronous Communication Asynchronous Communication Directional Capabilities of Data Exchange Line Configurations 30 Summary 31 Exercises 32 2 Transmission Media Transmission Line Characteristics Primary Parameters Secondary Parameters Phase Velocity and Phase Delay Frequency Dependence of Secondary Parameters Linear Distortions Group Delay Frequency Domain Equalizers Characteristics of Transmission Line in Time Domain Crosstalk Logarithmic Units of Power Level Measurements Metallic Transmission Media Balanced Pair Balanced Pair Cables Loading of Balanced Pairs Balanced Pair for Data Networks Coaxial Cable Optical Fibre Multimode Fibres Modal Dispersion Monomode Fibre Graded Index Fibres Chromatic Dispersion Total Dispersion Fibre Attenuation Advantages of Optical Fibre Radio Media Electromagnetic Spectrum Baseband Transmission of Data Signals First Nyquist Criterion Second Nyquist Criterion Channel Characteristic for Finite Duration Pulses Equalization Transversal Filter Equalizer Adaptive Equalization 59

6 CONTENTS v 2.11 Clocked Regenerative Receiver Eye Pattern 61 Summary 63 Exercises 63 3 Telephone Network Telephone Network Network Topology Single Exchange Area Multiple Exchanges Trunk Automatic Exchanges International Transit Exchange Transport Network Hybrids Multiplexing Pulse Code Modulation (PCM) Channel PCM Signal Plesiochronous Digital Hierarchy (PDH) Synchronous Digital Hierarchy (SDH) STM-1 Frame Structure Virtual Container (VC) VC VC Mapping of Data Signals on STM Higher Order SDH Signals Transmission Systems for Long Distance Network Echo in Transmission Systems Noise in Transmission Systems Intermodulation Noise Thermal and Shot Noise Psophometric Weighting Signal to Noise Ratio Companders Signal Impairments in the Telephone Network Impulse Noise Gain Hits and Dropouts Phase Hits Phase Jitter Single Frequency Interference Frequency Shift Integrated Services Digital Network (ISDN) ISDN Interface ISDN Devices Reference Interfaces 95

7 vi CONTENTS BRA Frame Structure Access Mechanism for D Channel in BRA Data Transmission Mechanisms of ISDN Data Communications on Telephone Network Hz Voice Channel Bandwidth ISDN Services Digital Point-to-Point Links ITU-T Recommendations for Voice Band Leased Circuits 99 Summary 100 Exercises Data Line Devices Digital Modulation Methods Amplitude Shift Keying (ASK) Frequency Shift Keying (FSK) Phase Shift Keying (PSK) Multilevel Modulation Gray Code PSK Modulator PSK Demodulator Differential PSK Differential BPSK Differential 4 PSK Quadrature Amplitude Modulation (QAM) Modem Types of Modems Scrambler and Descrambler Block Schematic of a Modem Additional Modem Features Standard Modems ITU-T V.21 Modem ITU-T V.22 Modem ITU-T V.22bis Modem ITU-T V.23 Modem ITU-T V.26 Modem ITU-T V.26bis Modem ITU-T V.26ter Modem ITU-T V.27 Modem ITU-T V.27bis Modem ITU-T V.27ter Modem ITU-T V.29 Modem ITU-T V.32 Modem ITU-T V.33 Modem ITU-T V.34 Modem ITU-T V.90 Modem 135

8 CONTENTS vii 4.6 Other Modems and Line Drivers Limited Distance Modems Baseband Modems Line Drivers Group Band Modems Digital Subscriber Line (DSL) Asymmetric Digital Subscriber Line (ADSL) Modulation Distance Limitations ITU-T Recommendations for ADSL xdsl Technologies Data Multiplexers Types of Data Multiplexers Frequency Division Multiplexers (FDMs) Time Division Multiplexers (TDMs) Statistical Time Division Multiplexers Buffer Protocol Bit Map Statistical Multiplexing Multiple-Character Statistical Multiplexing Multiplexed Data Frame for Error Control Capability Line Utilization Efficiency Comparison of Data Multiplexing Techniques 150 Summary 150 Exercises Error Control Transmission Errors Content Errors Flow Integrity Errors Methods of Error Control Coding for Detection and Correction of Content Errors Error Detection Error Correction Perfect Error Correcting Code Systematic Code Bit Error Rate (BER) Error Detection Methods Parity Checking Checksum Error Detection Cyclic Redundancy Check (CRC) Forward Error Correction Methods Block Parity Hamming Code Interleaved Codes Convolutional Codes 177

9 viii CONTENTS 5.5 Reverse Error Correction Stop and Wait Go-Back-N Selective Retransmission 182 Summary 183 Exercises Network Architecture Topology of a Computer Network Elements of Meaningful Communication Transport-Oriented Functions Interaction with the Subnetwork Quality of Transport Service Conversion of Signals Error Control Components of a Computer Network Architecture of a Computer Network Network Architecture Models Partitioning of a System Features of a Partitioned Structure Layered Architecture of a Computer Network Need for Standardization of Network Architecture Open System Interconnection Layered Architecture of the OSI Reference Model Application Layer Presentation Layer Session Layer Transport Layer Network Layer Data Link Layer Physical Layer Functionality of the Layered Architecture Hierarchical Communication Peer-to-Peer Communication OSI Terminology Service Interface Service Interface Primitives and Parameters Types of Services Data Transfer Modes Connection-Oriented Mode of Data Transfer Connectionless Mode of Data Transfer Supplementary Functions Multiplexing of Connections Segmenting, Blocking, and Concatenation of Data Units 207

10 CONTENTS ix 6.14 Other Layered Architectures TCP/IP Systems Network Architecture (SNA) Digital Network Architecture (DNA) Standards Making Organizations 209 Summary 211 Exercises The Physical Layer The Physical Layer Physical Connection Service Provided to the Data Link Layer Functions within the Physical Layer Relaying Function in the Physical Layer Physical Interface Physical Layer Standards EIA-232-D Digital Interface DTE/DCE Interface DTE and DCE Ports DCE-DCE Connection EIA-232-D Interface Specifications Mechanical Specifications Electrical Specifications Functional Specifications Procedural Specifications Common Configurations of EIA-232-D Interface Three-Wire Interconnection Three-Wire Interconnection with Loopback Null Modem Null Modem with Loopback and Multiple Crossovers Limitations of EIA-232-D EIA-449 Interface Mechanical Specifications Electrical Specifications Functional Specifications EIA ITU-T X.21 Recommendation Mechanical Specifications Electrical Specifications Functional Specifications Procedural Specifications X.21bis Recommendation 239 Summary 239 Exercises 240

11 Data Communications And Computer Networks 30% OFF Publisher : PHI Learning ISBN : Author : Prakash C. Gupta Type the URL : Get this ebook