Radio System Design for Telecommunications Third Edition

Roger L. Freeman

Radio System Design for Telecommunications

Radio System Design for Telecommunications Third Edition

Roger L. Freeman

Copyright 䊚2007 John Wiley & Sons, Inc. All rights reserved. Published by John Wiley & Sons, Inc., Hoboken, New Jersey Published simultaneously in Canada. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning or otherwise, except as permitted under Section 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923, 978-750-8400, fax 978-750-4470, or on the web at www.copyright.com. Requests to the Publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, 201-748-6011, fax 201-784-6008, or online at http:rrwww.wiley.comrgorpermission. Limit of liabilityrDisclaimer of Warranty: While the publisher and author have used their best efforts in preparing this book, they make no representation or warranties with respect to the accuracy or completeness of the contents of this book and specifically disclaim any implied warranties of merchantability or fitness for a particular purpose. No warranty may be created or extended by sales representatives or written sales materials. The advice and strategies contained herein may not be suitable for your situation. You should consult with a professional where appropriate. Neither the publisher nor author shall be liable for any loss, loss of profit or any other commercial damages, including but not limited to special, incidental, consequential or other damages. For general information on our other products and services or for technical support, please contact our Customer Care Department within the United States at 877-762-2974, outside the United States at 317-572-3995 or fax 317-572-4002. Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic form. For more information about Wiley products, visit our web site at www.wiley.com Library of Congress Cataloging in Publication Data: Freeman, Roger L. Radio system design for telecommunicationsr Roger L. Freeman.ᎏ3rd ed. p. cm. A ‘‘Wiley-Interscience publication.’’ Includes bibliographical references and index. ISBN: 978-0-471-75713-9 1. Radio relay systemsᎏDesign and construction. I. Title. TK6553.F722254 2006 621.384⬘156ᎏdc22 2006042354 Printed in the United States of America 10 9 8 7 6 5 4 3 2 1

For my daughter Rosalind

CONTENTS

Preface

xxi

Chapter 1

Radio Propagation 1 1.1 Introduction, 1 1.2 Loss in Free Space, 2 1.3 Atmospheric Effects on Propagation, 4 1.3.1 Introduction, 4 1.3.2 Refractive Effects on Curvature of Ray Beam, 4 1.3.3 Refractivity Gradients, 8 1.4 Diffraction EffectsᎏThe Fresnel Zone Problem, 14 1.5 Ground Reflection, 18 1.6 Fading, 19 1.6.1 Introduction, 19 1.6.2 Multipath Fading, 19 1.6.3 Power Fading, 20 1.6.4 K-Factor Fading, 22 1.6.5 Surface Duct Fading on Over-Water Paths, 23 1.7 From Another PerspectiveᎏA Discussion of Fading, 25 1.7.1 Comparison of Some Common Fading Types, 25 1.7.2 Blackout Fading, 28 1.8 Fade Depth and Fade Duration, 31 1.9 Penalty for Not Meeting Obstacle Clearance Criteria, 32 1.10 Attenuation Through Vegetation, 33

Chapter 2

Line-of-Sight Microwave Radiolinks 2.1 Objective and Scope, 37

37

vii

viii

CONTENTS

2.2

2.3

Initial Planning and Site Selection, 38 2.2.1 Requirements and Requirements Analyses, 2.2.2 Route Layout and Site Selection, 40

38

Path Profiles, 43 2.3.1 Determiniation of Median Value for K-Factor,

2.4

Reflection Point,

48

2.5

Site Survey, 51 2.5.1 Introduction, 51 2.5.2 Information Listing, 51 2.5.3 Notes on Site Visit, 53

2.6

Path Analysis, 54 2.6.1 Objective and Scope, 54 2.6.2 Unfaded Signal Level at the Receiver, 55 2.6.3 Receiver Thermal Noise Threshold, 58 2.6.4 Calculation of IF Bandwidth and Peak Frequency Deviation, 61 2.6.5 Pre-emphasisrDe-emphasis, 64 2.6.6 Calculation of Median Carrier-to-Noise Ratio ŽUnfaded., 67 2.6.7 Calculation of Antenna Gain, 69

2.7

Fading, Estimation of Fade Margin, and Mitigation of Fading Effects, 70 2.7.1 Discussion of LOS Microwave Fading, 70 2.7.2 Calculating Fade Margin, 71 2.7.3 Notes on Path Fading Range Estimates, 81 2.7.4 Diversity as a Means to Mitigate Fading, 82

2.8

Analysis of Noise on a FM Radiolink, 87 2.8.1 Introduction, 87 2.8.2 Sources of Noise in a Radiolink, 89 2.8.3 FM Improvement Threshold, 90 2.8.4 Noise in a Derived Voice Channel, 91 2.8.5 Noise Power Ratio ŽNPR., 95 2.8.6 Antenna Feeder Distortion, 103 2.8.7 Total Noise in the Voice Channel, 107 2.8.8 Signal-to-Noise Ratio for TV Video, 107

2.9

Path Analysis Worksheet and Example, 2.9.1 Introduction, 108

108

46

CONTENTS

2.9.2

Sample Worksheet,

ix

108

2.10 Frequency Assignment, Compatibility, and Frequency Plan, 113 2.10.1 Introduction, 113 2.10.2 Frequency PlanningᎏChannel Arrangement, 113 2.10.3 Some Typical ITU-R Channel Arrangements, 119 Chapter 3

Digital Line-of-Sight Microwave Radiolinks 133 3.1 Introduction, 133 3.1.1 Energy per Bit per Noise Density Ratio, EbrN0 , 134 3.2 Regulatory Issues, 135 3.3 Modulation Techniques, Spectral Efficiency, and Bandwidth, 138 3.3.1 Introduction, 138 3.3.2 Bit Packing, 138 3.3.3 Spectral Efficiency, 141 3.3.4 Power Amplifier Distortion, 143 3.4 Comparison of Several Types of Modulation, 144 3.4.1 Objective, 144 3.4.2 Definitions and Notation, 144 3.4.3 Modulation Format Comparison, 145 3.4.4 Notes on Implementation and BER Performance, 146 3.5 Some System Impairments Peculiar to Digital Operation, 150 3.5.1 Mitigation Techniques for Multipath Fading, 151 3.5.2 ITU-R Guidelines on Combating Propagation Effects, 153 3.6 Performance Requirements and Objectives for Digital Radiolinks, 155 3.6.1 Introduction, 155 3.6.2 Five Definitions, 155 3.6.3 Hypothetical Reference Digital Path ŽHRDP. for Radio-Relay Systems with a Capacity Above the Second Hierarchical Level, 155 3.6.4 Error Performance Objectives for Real Digital Radiolinks Forming Part of a High-Grade Circuit in an ISDN Network, 156

x

CONTENTS

3.6.5

3.7 3.8

3.9

Error Performance Objectives of a 27,500-km Hypothetical Reference Path, 159 3.6.6 Jitter and Wander, 160 3.6.7 Error Performance from a Telecordia Perspective, 161 Application of High-Level M-QAM to High-Capacity SDHrSONET Formats, 161 Considerations of Fading on LOS Digital Microwave Systems, 162 3.8.1 Introduction, 162 3.8.2 Other Views of Calculations of Fade Margins on Digital LOS Microwave, 163 3.8.3 Multipath Fading Calculations Based on TIA TSB 10-F, 164 3.8.4 Simple Calculations of Path Dispersiveness, 169 Path Analyses or Link Budgets on Digital LOS Microwave Paths, 170

Chapter 4 Forward Error Correction and Advanced Digital Waveforms 175 4.1 Objective, 175 4.2 Forward Error Correction, 175 4.2.1 Background and Objective, 175 4.2.2 Basic Forward Error Correction, 177 4.2.3 FEC Codes, 180 4.2.4 Binary Convolutional Codes, 187 4.2.5 Channel Performance of Uncoded and Coded Systems, 196 4.2.6 Coding with Bursty Errors, 201 4.3 Advanced Signal Waveforms, 207 4.3.1 Block-Coded Modulation ŽBCM., 207 4.3.2 Trellis-Coded Modulation ŽTCM., 210 4.3.3 Multilevel-Coded Modulation ŽMCLM., 211 4.3.4 Partial Response with a Soft Decoder, 213 Chapter 5

Over-the-Horizon Radiolinks 5.1 Objectives and Scope, 219 5.2 Application, 219 5.3 Introduction to Tropospheric Scatter Propagation,

219

220

CONTENTS

5.4

5.5

5.6 5.7

5.8

Chapter 6

xi

Tropospheric Scatter Link Design, 223 5.4.1 Site Selection, Route Selection, Path Profile, and Field Survey, 223 5.4.2 Link Performance Calculations, 224 Path CalculationrLink Analysis, 288 5.5.1 Introduction, 284 5.5.2 Path Intermodulation NoiseᎏAnalog Systems, 284 5.5.3 Sample Link Analysis, 289 Threshold Extension, 291 Digital Transhorizon Radiolinks, 292 5.7.1 Introduction, 292 5.7.2 Digital Link Analysis, 292 5.7.3 Dispersion, 294 5.7.4 Some Methods of Overcoming the Effects of Dispersion, 295 5.7.5 Some ITU-R Perspectives on Transhorizon Radio Systems, 297 Troposcatter Frequency Bands and the Sharing with Space Radio-Communication Systems, 300 5.8.1 Frequency Bands Shared with Space Services ŽSpace-to-Earth ., 300

Basic Principles of Satellite Communications 305 6.1 Introduction, Scope, and Applications, 305 6.2 Satellite SystemsᎏAn Introduction, 306 6.2.1 Satellite Orbits, 306 6.2.2 Elevation Angle, 308 6.2.3 Determination of Range and Elevation Angle of a Geostationary Satellite, 309 6.3 Introduction to Link Analysis or Link Budget, 311 6.3.1 Rationale, 311 6.3.2 Frequency Bands Available for Satellite Communications, 311 6.3.3 Free-Space Loss or Spreading Loss, 315 6.3.4 Isotropic Receive LevelᎏSimplified Model, 315 6.3.5 Limitation of Flux Density on Earth’s Surface, 316 6.3.6 Thermal Noise Aspects of Low-Noise Systems, 318 6.3.7 Calculation of CrN0 , 321

xii

CONTENTS

6.4

6.5

6.6

Chapter 7

6.3.8 Gain-to-Noise Temperature Ratio, GrT, 323 6.3.9 Calculation of CrN0 Using the Link Budget, 332 6.3.10 Calculation SrN, 337 Access Techniques, 343 6.4.1 Introduction, 343 6.4.2 Frequency Division Multiple Access ŽFMDA., 345 6.4.3 Brief Overview of Time Division Multiple Access ŽTDMA., 352 INTELSAT Systems, 354 6.5.1 Introduction, 354 6.5.2 INTELSAT Type A Standard Earth Stations, 354 6.5.3 INTELSAT Standard B Earth Stations, 360 6.5.4 INTELSAT Standard C Earth Stations, 361 6.5.5 INTELSAT Standard D Earth Stations, 361 6.5.6 INTELSAT Standard E Earth Stations, 363 6.5.7 INTELSAT Standard F Earth Stations, 364 6.5.8 Basic INTELSAT Space Segment Data Common to All Families of Standard Earth Stations, 364 6.5.9 Television Operation Over INTELSAT, 364 Domestic and Regional Satellite Systems, 372 6.6.1 Introduction, 372 6.6.2 Rationale, 373 6.6.3 Approaches to Cost Reduction, 373 6.6.4 A Typical Satellite Series that Can Provide Transponder Space for Enterprise Networks, 374

Digital Communications by Satellite 381 7.1 Introduction, 381 7.2 Digital Operations of a Bent-Pipe Satellite System, 382 7.2.1 General, 382 7.2.2 Digital FMDA Operation, 382 7.2.3 TDMA Operation on a Bent-Pipe Satellite, 394 7.3 Digital Speech Interpolation, 403 7.3.1 Freeze-Out and Clipping, 404 7.3.2 TASI-Based DSI, 405 7.3.3 Speech Predictive Encoding DSI, 406 7.4 INTELSAT TDMArDSI System, 407 7.4.1 Overview, 407

CONTENTS

7.5

7.6

7.7

Chapter 8

xiii

7.4.2 Frame, Multiframe, and Burst Format, 409 7.4.3 Acquisition and Synchronization, 415 7.4.4 Transponder Hopping, 415 7.4.5 Digital Speech Interpolation Interface, 415 Processing Satellites, 416 7.5.1 Primitive Processing Satellite, 417 7.5.2 Switched-Satellite TDMA ŽSSrTDMA., 418 7.5.3 IF Switching, 421 7.5.4 Intersatellite Links, 422 Performance Considerations for Digital Satellite Communications, 425 7.6.1 Hypothetical Reference Digital Path for Systems Using Digital Transmissio5 in the Fixed-Satellite Service, 425 7.6.2 BERs at the Output of a HRDP for Systems Using PCM Telephony, 426 7.6.3 Allowable Error Performance for a HRDP in the Fixed-Satellite Service Operating Below 15 GHz When Forming Part of an International Connection in an ISDN, 426 7.6.4 Allowable Error Performance for a HRDP Operating at or Above the Primary Rate ŽThe Impact of ITU-T Rec. 5.826., 428 Link Budgets for Digital Satellites, 431 7.7.1 Commentary, 431

Very Small Aperture Terminals 8.1 Definitions of VSAT, 439 8.2 VSAT Network Applications, 439 8.2.1 One-Way Applications, 440 8.2.2 Two-Way Applications, 441 8.3 Technical Description of VSAT Networks and Their Operations, 442 8.3.1 Introduction, 442 8.3.2 A Link Budget for a Typical VSAT Operation at Ku-Band, 442 8.3.3 Summary of VSAT RF Characteristics, 447 8.4 Access Techniques, 447 8.4.1 Random Access, 449 8.4.2 Demand-Assigned Multiple Access, 450

439

xiv

CONTENTS

8.5 8.6 8.7 Chapter 9

Chapter 10

8.4.3 Fixed-Assigned FDMA, 451 8.4.4 Summary, 452 8.4.5 Outbound TDM Channel, 452 A Modest VSAT Network in Support of Short Transaction Communications, 453 Interference Issues with VSATs, 457 Excess Attenuation Due to Rainfall, 460

Radio System Design Above 10 GHz 463 9.1 The ProblemᎏAn Introduction, 463 9.2 The General Propagation Problem Above 10 GHz, 464 9.3 Excess Attenuation Due to Rainfall, 467 9.3.1 Calculation of Excess Attenuation Due to Rainfall for LOS Microwave Paths, 469 9.4 Calculation of Excess Attenuation Due to Rainfall for Satellite Paths, 479 9.4.1 Calculation Method, 479 9.4.2 Rainfall Fade Rates, Depths, and Durations, 482 9.4.3 Site or Path Diversity, 483 9.5 Excess Attenuation Due to Atmospheric Gases on Satellite Links, 484 9.5.1 Example Calculation of Clear Air AttenuationᎏHypothetical Location, 487 9.5.2 Conversion of Relative Humidity to Water Vapor Density, 488 9.6 Attenuation Due to Clouds and Fog, 490 9.7 Calculation of Sky Noise Temperature as a Function of Attenuation, 492 9.8 The Sun as a Noise Generator, 493 9.9 Propagation Effects with a Low Elevation Angle, 495 9.10 Depolarization on Satellite Links, 495 9.11 Scintillation Fading on Satellite Links, 495 9.12 Trade-off Between Free-Space Loss and Antenna Gain, 496 Mobile Communications: Cellular Radio and Personal Communication Services 10.1 Introduction, 503 10.1.1 Background, 503 10.1.2 Scope and Objective, 504

503

CONTENTS

xv

10.2 Some Basic Concepts of Cellular Radio, 504 10.2.1 N-AMPS Increases Channel Capacity Threefold, 508 10.3 Radio Propagation in the Mobile Environment, 509 10.3.1 The Propagation Problem, 509 10.3.2 Several Propagation Models, 509 10.3.3 Microcell Prediction Model According to Lee, 512 10.4 ImpairmentsᎏFading in the Mobile Environment, 515 10.4.1 Introduction, 515 10.4.2 Classification of Fading, 516 10.4.3 DiversityᎏA Technique to Mitigate the Effects of Fading and Dispersion, 518 10.4.4 Cellular Radio Path Calculations, 521 10.5 The Cellular Radio Bandwidth Dilemma, 521 10.5.1 Background and Objectives, 521 10.5.2 Bit Rate Reduction of the Digital Voice Channel, 522 10.6 Network Access Techniques, 522 10.6.1 Introduction, 522 10.6.2 Frequency Division Multiple Access ŽFDMA., 523 10.6.3 Time Division Multiple Access ŽTDMA., 524 10.6.4 Code Division Multiple Access ŽCDMA., 527 10.7 Frequency Reuse, 535 10.8 Paging Systems, 538 10.8.1 What Are Paging Systems?, 538 10.8.2 Radio-Frequency Bands for Pagers, 538 10.8.3 Radio Propagation into Buildings, 538 10.8.4 Techniques Available for Multiple Transmitter Zones, 538 10.8.5 Paging Receivers, 539 10.8.6 System Capacity, 540 10.8.7 Codes and Formats for Paging Systems, 540 10.8.8 Considerations for Selecting Codes and Formats, 540

xvi

CONTENTS

10.9 Personal Communication Systems, 541 10.9.1 Defining Personal Communications, 541 10.9.2 Narrowband Microcell Propagation at PCS Distances, 541 10.10 Cordless Telephone Technology, 546 10.10.1 Background, 546 10.10.2 North American Cordless Telephones, 546 10.10.3 European Cordless Telephones, 546 10.11 Future Public Land Mobile Telecommunication System ŽFPLMTS., 549 10.11.1 Introduction, 549 10.11.2 Traffic Estimates, 549 10.11.2.1 Nonvoice Traffic, 551 10.11.2.2 PCS Outdoors, 551 10.11.2.3 PCS Indoors, 551 10.11.3 Estimates of Spectrum Requirements, 552 10.11.4 Sharing Considerations, 553 10.11.5 Sharing Between FPLMTS and Other Services, 554 10.12 Mobile Satellite Communications, 554 10.12.1 Background and Scope, 554 10.12.2 Overview of Satellite Mobile Services, 555 10.12.2.1 Existing Systems, 555 10.12.3 System Trends, 555 Chapter 11

Wireless LANs, 561 11.1 Definition, 561 11.2 IEEE802.11 and its Variants, 562 11.3 Wireless LANs and Other Wireless Technologies, 564 11.3.1 Benefits of a Centralized WLAN Architecture, 565 11.4 Wireless LAN Frequencies, 566 11.5 Wireless LAN Structures, 566 11.6 WLAN Capabilities, 567 11.6.1 Distance Capabilities, 567 11.6.2 The WLAN Signal, 567 11.6.2.1 Direct Sequence Spread Spectrum ŽDSSS., 567 11.6.2.2 Frequency Hop Spread-Spectrum ŽFHSS., 568

CONTENTS

11.7 11.8

Chapter 12

xvii

IEEE 802.11 Layers, 568 Software-Defined Radio and Cognitive Radio, 570 11.8.1 Software-Defined Radio Description, 570 11.8.2 Cognitive Radio, 570

High-Frequency (HF) Transmission Links, 573 12.1 General, 573 12.2 Applications of HF Radio Communication, 573 12.3 Typical HF Link Operation, Conceptual Introduction, 575 12.4 Basic HF Propagation, 575 12.4.1 Introduction, 575 12.4.2 Skywave Transmission, 577 12.5 Choice of Optimum Operating Frequency, 580 12.5.1 Frequency Management, 587 12.6 Propagation Modes, 598 12.6.1 Basic Groundwave Propagation, 598 12.6.2 Skywave Propagation, 599 12.6.3 Near-Vertical Incidence ŽNVI. Propagation, 602 12.6.4 Reciprocal Reception, 604 12.7 HF Communication Impairments, 605 12.7.1 Introduction, 605 12.7.2 Fading, 605 12.7.3 Effects of Impairments at the HF Receiver, 608 12.8 Mitigation of Propagation-Related Impairments, 611 12.9 HF ImpairmentsᎏNoise in the Receiving System, 613 12.9.1 Introduction, 613 12.9.2 Interference, 613 12.9.3 Atmospheric Noise, 616 12.9.4 Man-Made Noise, 622 12.9.5 Receiver Thermal Noise, 625 12.10 Notes on HF Link Transmission Loss Calculations, 625 12.10.1 Introduction, 625 12.10.2 Transmission Loss Components, 625 12.10.3 A Simplified Example of Transmission Loss Calculation, 634 12.10.4 Groundwave Transmission Loss, 635

xviii

CONTENTS

12.11 Link Analysis for Equipment Dimensioning, 640 12.11.1 Introduction, 640 12.11.2 Methodology, 641 12.12 Some Advanced Modulation and Coding Schemes, 643 12.12.1 Two Approaches, 643 12.12.2 Parallel Tone Operation, 643 12.12.3 Serial Tone Operation, 645 12.13 Improved Lincompex for HF Radio Telephone Circuits, 650 Chapter 13

Meteor Burst Communication 13.1 Introduction, 657 13.2 Meteor Trails, 658 13.2.1 General, 658 13.2.2 Distribution of Meteors, 660 13.2.3 Underdense Trails, 660 13.2.4 Overdense Trails, 661 13.3 Typical Meteor Burst Terminals and Their Operation, 663 13.4 System Design Parameters, 665 13.4.1 Introduction, 665 13.4.2 Operating Frequency, 666 13.4.3 Data Rate, 666 13.4.4 Transmit Power, 666 13.4.5 Antenna Gain, 666 13.4.6 Receiver Threshold, 666 13.5 Prediction of MBC Link Performance, 667 13.5.1 Introduction, 667 13.5.2 Receiver Threshold, 667 13.5.3 Positions of Regions of Optimum Scatter, 668 13.5.4 Effective Length, Average Height, and Radius of Meteor Trails, 670 13.5.5 Ambipolar Diffusion Constant, 671 13.5.6 Received Power, 671 13.5.7 Meteor Rate, 674 13.5.8 Burst Time Duration, 675 13.5.9 Burst Rate Correction Factor, 678 13.5.10 Waiting Time Probability, 679

657

CONTENTS

13.6 13.7 13.8 13.9 13.10

xix

DesignrPerformance Prediction Procedure, 683 Notes on MBC Transmission Loss, 683 MBC Circuit Optimization, 685 Meteor Burst Networks, 686 Privacy and the Meteor Burst Footprint, 686

Chapter 14

Interference Issues in Radio Communications 14.1 Rationale, 691 14.2 Spurious Response Interference Windows at a Receiver, 692 14.3 Typical Interference Control for Line-of-Sight Microwave and Satellite Communication Facilities, 693 14.3.1 Introduction, 693 14.3.2 Conceptual Approach to Interference Determination, 694 14.3.3 Applicable FCC Rule for Minimum Antenna Radiation Suppression, 699 14.3.4 Coordination Contours, 702 14.4 Victim Digital Systems, 704 14.5 Definition of CrI Ratio, 706 14.5.1 Example CrI Calculations Based on Ref. 6, 706 14.5.2 Example of Digital Interferer into Victim Digital System, 710 14.6 Obstructed Interfering Paths, 712 14.7 ITU-R Approach to Digital Link Performance Under Interference Conditions, 714 14.7.1 Gaussian Interference Environmentᎏ M-QAM Systems, 714

691

Chapter 15

Radio Terminal Design Considerations 721 15.1 Objective, 721 15.1.1 The Generic Terminal, 721 15.2 Analog Line-of-Sight Radiolink Terminals and Repeaters, 722 15.2.1 Basic Analog LOS Microwave Terminal, 722 15.3 Digital LOS Microwave Terminals, 725 15.3.1 Gray or Reflected Binary Codes, 728

xx

CONTENTS

15.3.2

15.4

15.5

15.6

15.7

The Antenna Subsystem for LOS Microwave Installations, 729 15.3.3 Analog Radiolink Repeaters, 740 15.3.4 Diversity Combiners, 741 15.3.5 Hot-Standby Operation, 749 15.3.6 Pilot Tones, 753 15.3.7 Service Channels, 755 15.3.8 Alarm and Supervisory Subsystems, 756 15.3.9 Antenna TowersᎏGeneral, 760 15.3.10 Waveguide Pressurization, 765 Tropospheric Scatter and Diffraction Installations: Analog and Digital, 766 15.4.1 Antennas, Transmission Lines, Duplexer, and Related Transmission Line Devices, 768 15.4.2 Modulator᎐Exciter and Power Amplifier, 769 15.4.3 FM Receiver Group, 770 15.4.4 Diversity Operation, 770 15.4.5 Isolation, 771 Satellite Communications, Terminal Segment, 772 15.5.1 Functional Operation of a ‘‘Standard’’ Earth Station, 772 15.5.2 The Antenna Subsystem, 777 15.5.3 Very Small Aperture Terminals ŽVSATs., 787 Cellular and PCS Installations: Analog and Digital, 788 15.6.1 Introduction, 788 15.6.2 Base Station or Cell Design Concepts, 789 15.6.3 The MTSO or MSC, 791 15.6.4 Personal Communication Services, 793 HF Terminals and Antennas, 794 15.7.1 Introduction, 794 15.7.2 Composition of Basic HF Equipment, 795 15.7.3 Basic Single-Sideband ŽSSB. Operation, 796 15.7.4 SSB System Considerations, 797 15.7.5 Linear Power Amplifiers, 798 15.7.6 HF Configuration Notes, 800 15.7.7 HF Antennas, 800

CONTENTS

15.8

Appendix 1

Meteor Burst Installations, 808 15.8.1 Yagi Antennas, 808

Availability of a Line-of-Sight Microwave Link 815 A1.1 Introduction, 815 A1.2 Contributors to Unavailability, 816 A1.3 Availability Requirements, 817 A1.4 Calculation of Availability of LOS Radiolinks in Tandem, 817 A1.4.1 Discussion of Partition of Unavailability, 817 A1.4.2 Propagation Availability, 819 A1.5 Improving Availability, 819 A1.6 Application to Other Radio Media, 820

Appendix 2 Reference Fields and Theoretical References; Converting RF Field Strength to Power A2.1 Reference FieldsᎏTheoretical References, A2.2 Conversion of Radio-Frequency ŽRF. Field Strength to Power, 823 Appendix 3 Index

xxi

Glossary of Acronyms and Abbreviations

821 821

825 837

PREFACE TO THE THIRD EDITION

This book provides the essential design techniques for radio systems that operate at frequencies of 3 MHz to 100 GHz and which will be employed in the telecommunication service. We may also call these wireless systems, wireless being synonymous with radio, Telecommunications is a vibrant industry, particularly on the ‘‘radio side of the house.’’ The major supporter of this upsurge in radio has been the IEEE and its 802 committees. We now devote an entire chapter to wireless LANs ŽWLANs. detailed in IEEE 802.11. We also now have subsections on IEEE 802.15, 802.16, 802.20 and the wireless metropolitan area network ŽWMAN.. WiFi, WiMax,, and UWB Žultra wideband. are described where these comparatively new radio specialties are demonstrating spectacular growth. Systems operating above 10 GHz are taking on more importance due to the shortage of radio frequency spectrum. We include the new look given to rainfall loss by the ITU-R organization. In this text the dividing line has been set at 10 GHz between where excess attenuation can basically be neglected and above which its impact on link design must be included. The U.S. armed forces set the line at 6 GHz. We recommend the ITU-R method for the calculation of excess attenuation due to rainfall. The reader is cautioned here because of seeming changes in approach by ITU-R to calculate rainfall loss. Chapter 12 covers broadband radio, and we have devoted an entire chapter to this subject because of its growing importance in telecommunication. This chapter also covers in some detail OFDM Žoffset frequency division multiplex., a comparatively new technique to transmit information in an interference environment. Cellular radio by satellite has not blossomed as forecasted in the last edition. On the other hand, VSAT Žvery small aperture satellite terminal. systems have indeed become popular with the user. The rationale for their deployment varies. They can of course be classified as an economic alternative to connectivity via the public switched telecommunication network ŽPSTN. and the term for this is bypass. Another example was a bank in an emerging nation where we offered a satellite communication course. This bank had 120 branches with no direct xxiii

xxiv

PREFACE

electrical communication among branches whatsoever. They solved this problem by installing a VSAT network with its hub located in the bank’s headquarters in the nation’s capital. Intentional bypass of the international PSTN may be another reason. In some countries, it is argued, that such networks are more cost-effective and efficient. For subject completeness, we continue with our chapters on high-frequency ŽHF. communications and meteor burst ŽMBC.. Few other texts cover these two radio transmission technologies, although they are still widely used by the U.S. armed forces ŽHF. and for cost-effective sensor systems Žmeteor burst.. The first 14 chapters are arranged in a hierarchical manner. For example, Chapter 1 deals with general propagation problems. Propagation peculiar to a certain radio transmission method is addressed by discussing topics such as tropospheric scatter, HF, meteor burst, and cellular radio. Chapters 2 and 3 deal with line-of-sight microwave transmission. Chapter 5, 6, 7, and 8 are outgrowths of this topic. Chapters 6, 7, and 8 depend on information discussed in Chapter 4 Žforward-error correction.. The reader is only expected to have a working knowledge of electrical communication, algebra, trigonometry, logarithms and time distributions. The decibel and its many derivative forms are used widely throughout. The more difficult communication concepts are referenced to other texts or standards for further reading or clarification. Nearly every key formula is followed by at least one worked example. A set of review questions and problems can be found at the end of each Chapter. These are meant as a review and can be worked out without resorting to other texts. We have followed international practice of labeling ITU Radio Communication Sector Ži.e., ITU-R. standards. For some of those standards produced before January 1, 1993, we use the older conventional CCIR nomenclature. Those standards published after that date are called ITU-R recommendations.

ACKNOWLEDGMENTS I would like to use this space to thank those professionals in telecommunications that took time out of their lives to graciously help in the preparation of the third edition of Radio System Design for Telecommunications. Many of this group also reviewed the second edition of the text. The order of listing is random, just as they come to my mind. Marshall Cross, who is probably one of the finest antenna designers in the country, kept me on the straight and narrow for antenna applications and link budgets. Marshall is chairman of Megawave Systems of Boylston, Massachusetts. Another contributor was Bob Egri now of Ma-Com in Lowell, Massachusetts. Bob provided numerous suggestions on the book content and correctness of my assumptions.

PREFACE

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I am greatly indebted to Dr. Donald Schilling, professor emeritus in electrical engineering of City College of New York, for his support and suggestions. I am still again indebted to Susan Hoyler of the Telecommunication Industries Association ŽTIA. in Arlington, Virginia. She helped assure me that I was applying the right EIArTIA standard and that it had not been superseded. My thanks to Fran Drake of the electrical engineering department at the University of Wisconsin, Madison where I have been giving seminars on telecommunication transmission, radio systems, and data networks for more than 20 years. His critique has been invaluable. Another reviewer and supporter during the preparation of this text was Dr. Enric Vilar, a Catalan of great fame in the world of electromagnetic propagation. He recently retired as telecommunications department head at Portsmouth Polytechnic University, UK and has moved back to Barcelona. Enric and I worked together at ITT laboratories, Madrid. I would like to devote space to a dedicated friend and colleague in electrical engineering, Donald J. Marsh. Don died during the period of preparation of this edition. He had just retired from ITT World Headquarters in New York City. I worked for and with Don over many years, particularly at ITT Communication Systems in New Jersey and at ITT Laboratories in Madrid, Spain. He was a very dear colleague, and the electrical engineering community is going to sorely miss him. I also wish to thank my dear wife, Paquita, for her patience and support throughout the entire preparation cycle of the text. ROGER L. FREEMAN Scottsdale, Arizona January 2007

1 RADIO PROPAGATION 1.1 INTRODUCTION The purpose of this book is to describe methods of the design of radio systems for telecommunications that operate approximately from 3 MHz to 300 GHz. These systems include line-of-sight ŽLOS . microwave, diffractionrscatter links, satellite links, and very small aperture terminal ŽVSAT. systems ŽRefs. 1᎐5.. Such systems may be described as broadband. The book also covers narrowband systems such as high frequency ŽHF; i.e., in the 3᎐30-MHz band.. Also a chapter is devoted to cellular radio systems and personal communication systems ŽPCSs.. Such systems are commonly part of a larger system, the public switched telecommunication network ŽPSTN.. A common thread throughout such systems is propagation. Free-space loss and fading are examples. There are also some notable differences such as the propagation behavior of HF compared to LOS microwave. This chapter covers topics in propagation that have commonality between at least two of the subject areas. However, those propagation issues peculiar to each of the transmission types are dealt with in the appropriate chapter. We have made an arbitrary division of the radio spectrum of interest at 10 GHz. In general, for those systems operating below 10 GHz, we can say that atmospheric absorption and precipitation play a secondary role, and with many systems these issues are neglected. For those systems operating above 10 GHz, excess attenuation due to rainfall and losses due to atmospheric gases may become principal issues. In the following discussion we use the isotropic as the reference antenna.* The IEEE dictionary ŽRef. 1. defines an isotropic radiator as ‘‘a hypothetical *The reader must take care in this instance. Almost without exception in cellular systems, the reference antenna is a dipole. Such a reference may also be encountered in PCS and HF systems. A reference dipole has a 2.15-dB gain over the isotropic antenna. Radio System Design for Telecommunications, Third Edition By Roger L. Freeman Copyright 䊚 2007 John Wiley & Sons, Inc.

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RADIO PROPAGATION

Figure 1.1. A point source isotropic radiator located at the center of a sphere.

lossless antenna having equal radiation intensity in all directions.’’ An isotropic antenna has a gain of 1 Žin decimal units. or a gain of 0 dB. The decibel unit of antenna gain Žor loss. is the dBi Ždecibels referenced to an isotropic..

1.2 LOSS IN FREE SPACE Loss in free space is a function of frequency squared plus distance squared plus a constant. Let’s see how this relationship is developed. Consider power PT radiated from an isotropic transmitting antenna. This transmitting antenna is a point source radiating power uniformly in all directions. Let’s imagine a sphere with radius d, which is centered on that point source. This concept is shown in Figure 1.1. If free-space transmission is assumed, meaning transmission with no absorption or reflection of energy by nearby objects, the radiated power density will be uniform at all points on the sphere’s surface. The total radiated power PT will pass outward through the sphere’s surface. The radially directed power density at any point on the surface of the sphere is Power density s PT r4␲ d 2

Ž 1.1 .

If a receiving antenna with an effective area A R is located on the surface of the sphere, the total receive power PR is equal to the power density times the area of the antenna. This is expressed as PR s PT = A Rr4␲ d 2

Ž 1.2 .

A transmitting antenna with an effective area of AT , which concentrates its radiation within a small solid angle or beam, has an on-axis transmitting antenna gain, with respect to an isotropic radiator, of g T s 4 ␲ A T r␭ 2

Ž 1.3 .

where ␭ is the wavelength of the emitted signal. Let’s use this antenna in place of the familiar isotropic radiator. The receive power relationship in