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DATA COMMUNICATIONPRINCIPLES For Fixed and Wireless Networks... Network Protocol Architecture OSI-RM Characteristics and Terminology Communications Model within an OSI Node Communication

DATA COMMUNICATION

PRINCIPLES

For Fixed and Wireless Networks

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DATA COMMUNICATION

PRINCIPLES

For Fixed and Wireless Networks

Aftab Ahmad

KLUWER ACADEMIC PUBLISHERS

NEW YORK, BOSTON, DORDRECHT, LONDON, MOSCOW

eBook ISBN: 0-306-47793-9

Print ISBN: 1-4020-7328-3

©2002 Kluwer Academic Publishers

New York, Boston, Dordrecht, London, Moscow

Print ©2003 Kluwer Academic Publishers

All rights reserved

No part of this eBook may be reproduced or transmitted in any form or by any means, electronic, mechanical, recording, or otherwise, without written consent from the Publisher

Created in the United States of America

Visit Kluwer Online at: http://kluweronline.com

and Kluwer's eBookstore at: http://ebooks.kluweronline.com

Dordrecht

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To my parents

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The Computer System

The Communications System

The Networking System

1.2 Network Development Example

1.2.1 Three Role Players

1.2.2 Network Design

1.3 Standardization

1.3.1

1.3.2

Example 1 - Communication of Voice

Example 2 - File Transfer

1.4 Classification of Networks

1.4.1

1.4.2

1.4.3

Local Area Networks (LANs)

Wide Area Networks (WANs)

Metropolitan Area Networks (MANs)

1.5 Network Protocol Architecture

OSI-RM Characteristics and Terminology

Communications Model within an OSI Node

Communications Across the OSI Network

Inter-layer communication

OSI-RM Layer Definitions and Functions

2.2 The TCP/IP Protocol Suite

2.2.1

2.2.2

2.2.3

2.2.4

The Internet Protocol (IP)

The Transmission Control Protocol (TCP)

The Application Protocols for the Internet

Lower Layers of the Internet

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22345569910121212131313131414151516

17

1818192223253639404141

Local Area Networks

Wireless Local Area Networks

The Physical Layer (PHY)

The Medium Access Control (MAC) Layer

International Telecommunications Union (ITU)

The Internet Society

International Organization for Standardization (ISO)

European Telecommunications Standards Institute (ETSI)

American National Standard Institute (ANSI)

Institute of Electrical and Electronic Engineers (IEEE)

The Network Data

The Physical Layer Data

Sequence of Events and Definitions

Modulation of data and signals

Digital Encoding of Data

Non-Return to Zero (NRZ)

Multilevel Encoding

Manchester Coding

General Characteristics of Bit Encoding

Zero-substitution and nB/NB Translation

Amplitude Shift Keying (ASK)

Frequency Shift Keying (FSK)

Phase Shift Keying (PSK)

3.5 The User Data

3.5.1

3.5.2

3.5.3

3.5.4

Digital Transmission of Voice

The Sampling Theorem

Pulse Coded Modulation (PCM)

Delta Modulation

3.6 Text and Numerical Data

3.6.1 ASCII (American National Standard Code for InformationInterchange)

3.6.2 ISO 8859-1 (ISO Latin -1)

424243454647484949505050515253

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56575767707172737475767677808081828484858591939495

Optical Fiber Cable (OFC)

4.4 The Wireless Media

4.4.1

4.4.2

Characteristics

Examples of Wireless Bands

4.5 Physical Layer Protocol Example: EIA-232-F

5 Data Link Control Layer Functions and Procedures

5.1 Data Link Layer Functions

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Block Error Check

The Cyclic Redundancy Check (CRC)

Stop-and-Wait (SnW) Flow Control

The Sliding-windows (SW) Flow Control Mechanism

Link Utilization of Window Flow Control Mechanisms

Full-duplex Communications Using Window Flow Control

5.7 Flow Control Based Error Recovery Mechanisms

Selective Reject ARQ

Maximum Window Size

Normal Response Mode (NRM)

Asynchronous Balanced Mode (ABM)

Asynchronous Response Mode (ARM)

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6.7.1 The ATM Cell

6.8 ATM Protocol Procedures

The Distributed Coordination Function (DCF)

MAC Frame Structure

MAC Frame Types

6.10 Review Questions

7 Multiplexing and Carrier Systems

7.1 Analog and Digital Transmissions

Analog and Digital Multiplexing

Frequency Division Multiplexing (FDM)

Frequency Division Duplexing (FDD)

Time Division Multiplexing (TDM)

Digital Carrier Systems

The DS-1 Carrier System

Problems with T-1/E-1 Systems

7.4 Synchronous Optical Network/ Synchronous Digital Hierarchy

7.5 Digital Subscriber’s Line (DSL)

7.5.1 8.1 Integration With Telephone

7.6 Multiplexing at higher layers

The Network Layer

Typical Functions of Network layer

The End-to-end Layers

X.25 Packet Layer Protocol

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267 273

The Network Performance

Performance of the Physical Layer Protocols

9.2.1 Performance Improvement at PHY

9.3 Data Link Layer Performance

9.3.1

9.3.2

Flow Control Procedures

Error Control Procedures

9.4 Performance of the MAC Sublayer

9.5 Performance of the network and higher layers

9.5.1

9.5.2

9.5.3

Connectionless and Connection-oriented Protocols

QoS Differentiation in Connectionless Protocols

Performance of End-to-end Protocols

9.6 System Simulation for Performance Prediction

9.6.1

9.6.2

What is Simulation?

Designing a Simulation Program Versus Using a Package

9.7 Performance of Wireless and Mobile Networks

9.7.1

9.7.2

9.7.3

The Wireless Network Channel

Resource Management in Wireless Networks

Mobility Management in Mobile Networks

9.8 Review Questions

References

Index

In spite of the fact that the electronic communication systems started

as data communication systems, much of their advancement has been in thefield of voice For decades, the Public Switched TelecommunicationsNetwork (PSTN) has set standards for communication of information all overthe world Things started changing only towards the closing of 80s whenInternet and mobile systems offered competition in some ways Despite thecontinued importance of PSTN, these two technologies have found their niche

to sustain and grow Wireless networks offer mobility as an add-on and theInternet brought the web, email and file transfer Though PSTN could providethe Internet-like services, it has its limitations due to its circuit switchednature For some time, we have used the term data to distinguish the store-and-forward type of information (carried by Internet) from voice This isbecause the Internet uses store and forward mechanism of transmission, which

is not quite suitable for interactive, real-time communication, such as voice

In this way, PSTN, Internet and wireless networks have not quitestood in each other’s way PSTN offering toll-quality digitized voice, wirelesscellular networks adding mobility to voice and data, with some degradation inquality, and the Internet allowing enormous sharing power using store-and-forward protocols for data communications Ever since their debut, all thesefields of technologies have made progress, with PSTN being steady and slow,Internet being slow first and then exploding, and the wireless technologymaking a steady progress at a rapid speed It is only very recently that there is

a slowing in wireless market However, with ever-increasing products inlicense-free wireless band, this is projected to change soon The emphasis,however, may shift from voice to web-based applications In fact, with theavailability of high-speed ‘data’ links, voice is becoming part of ‘data’

Traditionally, data was generated and processed by mainframecomputers Users accessed the computer resources through a network of dumbterminals With developments in microchip fabrication, and reduction inmemory cost, processing power shifted to terminals making them intelligent,and then as powerful as the computer itself These days, desktop computersare mostly the processing powerhouses that mainframes once were And thesemachines are capable of processing data at speeds that could easily take care

of the requirements of interactive information The introduction of IMT-2000systems in wireless arena has reduced the gap in wireless, voice and data.Now we talk about multimedia wireless networks that could use Internet as abackbone Consequently, the entire meaning of data and communications haschanged to include real-time information and wireless networks For a studentand practitioner of data networks, the fundamental concepts of networks with

latest technology have become more important to master than ever before Ofcourse, by latest technologies, we mean packet switching and wireless datanetworks This book has been written with these developments in mind

The primary audience of this book is the students, seniorundergraduate or first year graduate, and personnel in the fields of computerscience, electrical engineering, telecommunications, information systems, andother majors that require an elementary to medium level knowledge of datacommunications principles Much of the material has been used to offergraduate and undergraduate level courses in some of the above areas Thebook is a compilation from lecture notes with some addition The approachadopted is rather straightforward; define a data network as a computercommunication network that could be best understood with the help of theOpen System Interconnection Reference Model (OSI-RM), recommended bythe International Organization for Standardization (ISO) The OSI networkingstandards are not nearly as prolific in use as the Internet protocols, still thepedagogical value of the reference model makes it a good choice for a firstcourse on data communications Besides, the main differences between theOSI and TCP/IP networks exist at layers above the data link control Thebook emphasizes only on the bottom two layers, therefore making it useful forpeople who would work with TCP/IP, OSI or Local Area Network Examples

of protocols are chosen, among others, from the wireless data networks Thisbroadens the scope of the application of work Another salient feature of thebook is a chapter on performance modeling of data networks This is a topicthat results in most innovations in technology, and yet is not easy to introduce

at an elementary level Every try has been made to let the reader appreciatethe models and metrics of performance measures Separate discussions havebeen included about the wireless cellular network performance and simulation

of networks Here’s the organization of chapters

A major part of the book is dedicated to the understanding of data andits transmission across a single link However, to put things in perspective, thefirst two chapters discuss the protocol architectures in general Examples ofOSI-RM, TCP/IP suite and IEEE Wireless LAN are discussed under thistopic Chapter 3 discusses data in most of its forms, from analog form tocharacters and as data exists within the network (baseband signal, passbandmodulated signal, to protocol data unit) Chapter 4 discusses physical layercharacteristics and protocol examples Among the protocol examples, adiscussion on the physical layers of IEEE Wireless LAN has been included.Simple descriptions of some important concepts have been provided here,such as the need of physical medium dependent (PMD) sublayer, and termssuch as spread spectrum communications Chapter 5, a rather lengthy one, isdevoted to the discussion of functions and duties of the data link control layer.Chapter 6 builds on Chapter 5 using example protocols HDLC, ATM andIEEE 802.11 MAC have been discussed Chapter 7 is on multiplexing and

carrier systems, that make the backbone of transmission systems T-1, thoughreceding in its deployment, still makes an excellent case of studying a carriersystem Discussions on SONET/SDH and DSL are also included in thischapter Chapter 8 provides a one shot treatment of the layers above the linklayer Terminology pertinent to these layers in introduced here Chapter 9completes the understanding, albeit at an elementary level, by discussing thetopic of performance The material in the book, proposed to be covered in onesemester, could be adjusted according to the specialty of the audience.

In the end, I would like to thank and acknowledge numerousanonymous people who have contributed to this field in many ways I haveused many books, articles, websites and documents of numerous companiesand standardization agencies in learning the subject, some repeatedly Thanksare due to the reviewers of the manuscript Also, thanks are due to thecompanies that designed software and hardware that went in preparing themanuscript I also take this opportunity to thank Alex Green of the KluwerAcademic Publishers for his persistence in making this book a reality Thanksare due to Melissa Sullivan and Deborah Doherty of the Kluwer AcademicPublishers for help with formatting the manuscript Most of all, I am muchindebted to my wife for her patience during the preparation of the manuscript,especially during the final stage

Aftab Ahmad

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1 Computer Communications Networks - Introduction

The purpose of a computer communications network is to allowmoving information from one point to another inside the network Theinformation could be stored on a device, such as a personal computer in thenetwork, it could be generated live outside the network, such as speech, orcould be generated by a process on another piece of information, such asautomatic sales transactions at the end of a business day The device does notnecessarily have to be a computer; it could be a hard disk, a camera or even aprinter on the network Due to a large variety of information to be moved, anddue to the fact that each type of information has its own conditions forintelligibility, the computer network has evolved into a highly complexsystem Specialized knowledge from many areas of science and engineeringgoes into the design of networks It is practically impossible for a single area

of science or engineering to be entirely responsible for the design of all thecomponents Therefore, a study of computer networks branches into manyareas as we go up from fundamentals to the advanced levels

Advancements in communication of speech have long been matured

in the form of public switched telephone network (PSTN) However, design

of store-and-forward type of networks, such as the Internet, is far frommatured - perhaps due to proliferation of the ways in which such networks areused The integration of the two types of networks is the culmination oftelecommunications technology It is not futuristic to imaginetelecommunications networks meeting the needs of live traffic (e.g., phonecalls) as well as store-and-forward data (e.g., email) traffic according to thedesired quality of service

In this chapter, we look at a computer network as a whole, from both

an application point of view and a design point of view In fact, the design andapplication influence each other so much that a study of the fundamentals ispractically impossible by leaving either one out

be more descriptive when live speech and video could not be transmitted over such networks At that time, data meant store and forward type of information that had no real-time content Examples of such information are file, email and logon programs With time, definition of data has changed (see Chapter 3), and so has the definition of data networks A data network now includes all of the above The telephone network could be seen as an exception, even though it is also been used as data network in many of its applications However, due to its circuit-switched nature, it is not projected to belong to computer networks.

1.1.1 The Computer System

Computer systems are stand-alone systems, along with peripheraldevices, capable of performing information input, output, storage andprocessing The study and design of computer systems is the job of computerscientists and engineers

Computer systems usually consist of hardware (processor, memory,storage devices and input and output devices), system software for userinterface and resource management, such as operating system and specialpurpose software such as programming languages, database managementsystem, text-processing systems etc Developments in microchip have led tothe utilization of processor technology in everyday appliances, making allnetworkable devices operating like a computer system

Examples of computer systems are: personal computers, notebookcomputers, and data acquisition systems

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The Computer System

The Communications System

The Networking System

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