Wireless and cellular telecommunications

Đây là cuốn sách gối đầu giường của dân Điện tử viễn thông. Trình bày rõ về thông tin di động, wireless và phạm vi hoạt động của nó.

WIRELESS AND

CELLULAR

TELECOMMUNICATIONS

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WIRELESS AND

CELLULAR TELECOMMUNICATIONS

William C Y Lee, Ph.D.

Chairman, Treyspan, Inc

(Formerly Vice President and Chief Scientist ofVodafone AirTouch PLC, and Chairman ofLinkAir Communications, Inc.)

Third Edition

McGRAW-HILL

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Preface xix

Preface to the First Edition xxi

Acknowledgments xxiii

1.1 History of Mobile Cellular / 1

1.1.1 AMPS System (First-Generation System) / 1

1.1.2 Second-Generation System / 2

1.1.3 3G Systems / 3

1.1.4 4G Systems / 4

1.1.5 Other Cellular-Like Systems / 4

1.2 Wireless Data Networks / 5

1.2.1 General Description / 5

1.2.2 Wireless LAN Standards / 6

1.2.3 Wireless WAN Evolution / 6

1.3 Communication Satellite Systems / 7

1.5.1 International Standard Bodies / 11

1.5.2 Standards Bodies in Different Areas / 13

1.6 Spectrum Allocation / 15

1.6.1 Spectrum Allocation in the United States / 16

1.6.2 ITU: Spectrum for 3G (IMT-2000) / 18

1.6.3 The Other Areas of the World / 19

1.7 Spectrum Efficiency Considerations / 20

2.1 Basic Cellular Systems / 23

vi CONTENTS

2.3 Uniqueness of Mobile Radio Environment / 28

2.3.1 Description of Mobile Radio Transmission Medium / 28

2.3.2 Model of Transmission Medium / 30

2.3.3 Mobile Fading Characteristics / 32

2.3.4 Direct Wave Path, Line-of-Sight Path, and Obstructive

2.4.2 Maximum Number of Calls Per Hour Per Cell / 42

2.4.3 Maximum Number of Frequency Channels Per Cell / 44

2.5 Concept of Frequency Reuse Channels / 45

2.5.1 Frequency Reuse Schemes / 45

2.5.2 Frequency Reuse Distance / 46

2.5.3 Number of Customers in the System / 47

2.6 Cochannel Interference Reduction Factor / 48

2.7 Desired C/I from a Normal Case in an Omnidirectional Antenna System / 49

2.11 Different Cellular Systems and B3G-Systems / 57

3.1 Definitions of Terms and Functions / 59

3.2 Specification of Mobile Station (Unit) in the United States / 61

3.3.5 Additional Spectrum Radio (ASR) Issues / 78

3.4 Different Specifications of the World’s Analog Cellular Systems / 79

4.1 Introduction to Digital Systems / 85

4.1.1 Advantages of Digital Systems / 85

4.1.2 Digital Technologies / 86

4.2.6 Channel Coding and Interleaving / 121

4.2.7 Radio Resource (RR) Management / 124

4.3.3 Transmission and Modulation / 131

4.3.4 Time Alignment and Limitation of Emission / 137

4.4.1 Terms of CDMA Systems / 147

4.4.2 Output Power Limits and Control / 149

5.3 HSCSD (High Speed Circuit Switched Data) / 196

5.4 iDEN (Integrated Digital Enhanced Network) / 197

5.4.1 History / 197

viii CONTENTS

5.4.2 Description of iDEN’s Attributes / 197

5.4.3 iDEN’s Unique Features / 198

5.4.4 iDEN Communications Network / 198

5.4.5 Radio Link / 202

5.4.6 Dispatch Call Processing / 206

5.4.7 Packet Data Networking / 209

5.5 PHS (Personal Handy Phone System) / 211

5.5.1 Introduction / 211

5.5.2 PHS Network Structure and System Components / 211

5.5.3 Value Added Service Platform / 212

6.1 WCDMA-UMTS (UTRA-FDD) Physical Layer / 226

6.1.1 Description of Physical Layer / 226

6.1.2 Transport Channels / 228

6.1.3 Physical Channels / 229

6.1.4 Transmission Characteristics / 230

6.1.5 User Data Transmission / 233

6.1.6 Physical Layer’s Functions / 234

6.2 WCDMA-ARIB Physical Layer / 235

6.2.1 FDD Mode / 235

6.2.2 TDD Mode / 239

6.2.3 Common Physical Layers for Both FDD and TDD Modes / 239

6.3 WCDMA-TDD Physical Layer / 240

6.3.1 WCDMA-TDD Channel Structure / 240

6.3.2 Channel Mapping / 241

6.3.3 Spreading (Channelization) Codes / 241

6.3.4 Modulation and Spreading / 242

6.3.5 Bandwidth Requirement and Capacity / 242

6.4 UMTS Network Architecture / 243

6.4.7 Overview of 3GPP Release 99 Network / 250

6.5 Evolution of UMTS-3GPP Release 4 and Beyond (Release 5, 6, 7) / 254

6.5.1 Release 4 Core Network Architecture / 254

6.6.2 Radio Interface Parameters of cdma2000 FDD / 265

6.6.3 Transmission Characteristics for cdma2000 TDD / 270

6.8 cdma2000 EV-DO and EV-DV / 285

6.8.1 Forward Link Physical Layer / 285

6.8.2 Forward Link MAC Layer / 288

6.8.3 Reverse Link Physical Layer / 289

7.2.1 PPM, DSSS, and FHSS Transmission Technologies / 297

7.2.2 OFDM (Orthogonal Frequency Division Multiplexing) Technology / 298 7.2.3 Generic Physical Layer / 305

7.2.4 Physical Layer for Specific Systems (802.11 b/a/g) / 307

7.2.5 Available Bandwidth for Specific Systems (802.11b/a/g) / 309

7.2.6 802.11a/b/g Throughput Comparisons / 312

7.2.7 802.11b and 802.11g Coexistence / 313

7.2.8 MAC (Media Access Control) Layer / 315

7.2.9 Wi-Fi / 328

7.3 Hot Spot / 329

7.4 802.16 and Associated Standards / 331

7.4.1 802.16a (a BWA System) / 332

8.1.1 Ground Incident Angle and Ground Elevation Angle / 350

8.1.2 Ground Reflection Angle and Reflection Point / 350

8.2 Obtaining the Mobile Point-to-Point Model (Lee Model) / 351

8.2.5 The Straight-Line Path-Loss Slope with Confidence / 359

8.2.6 Determination of Confidence Interval / 361

8.2.7 A General Formula for Mobile Radio Propagation / 362

8.2.8 Comments on the Propagation Models / 363

8.3 Propagation Over Water or Flat Open Area / 363

8.3.1 Between Fixed Stations / 364

8.3.2 Land-to-Mobile Transmission Over Water / 366

x CONTENTS

8.4 Foliage Loss / 367

8.5 Propagation in Near-in Distance / 369

8.5.1 Why Use a 1-mi Intercept? / 369

8.5.2 Curves for Near-in Propagation / 370

8.5.3 Calculation of Near-Field Propagation / 372

8.7.3 Cautions in Obtaining Defraction Loss / 381

8.8 Form of a Point-to-Point Model / 381

8.8.1 General Formula of Lee Model / 381

8.8.2 The Merit of the Point-to-Point Model / 382

8.9 Computer Generation of A Point-to-Point Prediction / 383

8.9.1 Terrain Elevation Data / 384

8.9.2 Elevation Map / 385

8.9.3 Elevation Contour / 386

8.10 Cell-Site Antenna Heights and Signal Coverage

Cells / 387

8.10.1 Effects of Cell-Site Antenna Heights / 387

8.10.2 Visualization of Signal Coverage Cells / 388

8.12.3 Power Spectrum of the Complex Envelope / 394

8.13 Antennas at Cell Site / 396

8.13.1 For Coverage Use: Omnidirectional Antennas / 396

8.13.2 For Interference Reduction Use: Directional Antennas / 397 8.13.3 Location Antennas / 400

8.13.4 Setup-Channel Antennas / 400

8.13.5 Space-Diversity Antennas Used at Cell Site / 400

8.13.6 Umbrella-Pattern Antennas / 400

8.13.7 Interference Reduction Antenna / 402

8.14 Unique Situations of Cell-Site Antennas / 402

8.14.1 Antenna Pattern in Free Space and in Mobile Environments / 402 8.14.2 Minimum Separation of Cell-Site Receiving Antennas / 403 8.14.3 Regular Check of the Cell-Site Antennas / 404

8.14.4 Choosing an Antenna Site / 404

8.16.3 Mobile High-Gain Antennas / 413

8.16.4 Horizontally Oriented Space-Diversity Antennas / 415

8.16.5 Vertically Oriented Space-Diversity Antennas / 415

8.17 Handsets, Antennas, and Batteries / 416

8.17.1 Handset Considerations / 416

8.17.2 RF Antenna Characterization / 417

9.2 Exploring Cochannel Interference Areas in a System / 426

9.2.1 Test 1: Find the Cochannel Interference Area from a Mobile

9.5 Design of a Directional Antenna System / 432

9.5.1 Directional Antennas In K = 7 Cell Patterns / 433

9.5.2 Directional Antenna in K = 4 Cell Pattern / 435

9.5.3 Comparing K = 7 and K = 4 Systems / 436

9.6 Lowering the Antenna Height / 436

9.6.1 On a High Hill or a High Spot / 437

9.7.4 Suggested Method for Reducing Interference / 442

9.7.5 Cautions in Tilting Antennas / 443

9.8 Umbrella-Pattern Effect / 443

9.8.1 Elevation Angle of Long-Distance Propagation / 444

9.8.2 Benefit of the Umbrella Pattern / 444

9.9 Use of Parasitic Elements / 445

9.10 Power Control / 447

9.10.1 Who Controls the Power Level / 447

9.10.2 Function of the MSO / 447

9.10.3 Reduction of Code Channel Interference / 448

10.1 Subjective Test versus Objective Test / 455

10.1.1 The Subjective Test / 455

10.1.2 The Objective Test / 457

10.1.3 Measurement of SINAD / 457

10.2 Adjacent-Channel Interference / 458

10.2.1 Next-Channel Interference / 458

10.2.2 Neighboring-Channel Interference / 459

xii CONTENTS

10.2.3 Transmitting and Receiving Channels Interference / 459

10.2.4 Interference from Adjacent Systems / 460

10.3 Near-End–Far-End Interference / 460

10.3.1 In One Cell / 460

10.3.2 In Cells of Two Systems / 461

10.4 Effect on Near-End Mobile Units / 462

10.4.1 Avoidance of Near-End–Far-End Interference / 462

10.4.2 Nonlinear Amplification / 464

10.5 Cross Talk—A Unique Characteristic of Voice Channels / 465

10.6 Effects on Coverage and Interference by Applying Power Decrease, Antenna Height

Decrease, and Beam Tilting / 467

10.6.1 Choosing a Proper Cell Site / 467

10.7.2 Demultiplexer at the Receiving End / 474

10.7.3 SAT Tone of AMPS System / 475

10.8 Interference between Systems / 477

11.1 Value of Implementing Handoffs / 485

11.1.1 Why Handoffs / 485

11.1.2 Types of Handoff / 485

11.1.3 Two Decision-Making Parameters of Handoff / 486

11.1.4 Determining the Probability of Requirement for Hard Handoffs / 487

11.1.5 Number of Hard Handoffs Per Call / 487

11.1.6 Area of Soft Handoffs in a Cell / 488

11.2 Initiation of a Hard Handoff / 489

11.7 Mobile Assisted Handoff (MAHO) and Soft Handoff / 496

11.8 Cell-Site Handoff Only / 496

11.9 Intersystem Handoff / 497

11.10 Introduction to Dropped Call Rate / 498

11.10.1 The Definition of Dropped Call Rate / 498

11.10.2 Consideration of Dropped Calls / 498

CONTENTS xiii

11.10.3 Relationship Among Capacity, Voice Quality, Dropped

Call Rate / 499

11.10.4 Coverage of 90 Percent Equal-Strength Contour / 499

11.11 Formula of Dropped Call Rate / 500

11.11.1 General Formula of Dropped Call Rate / 500

11.11.2 Commonly Used Formula of Dropped Call Rate / 501

11.11.3 Handoff Distribution of Calls,α n / 502

11.12 Finding the Values ofδ and µ Used for Dropped Call Rate / 502

11.12.1 Formula forδ and µ / 503

11.12.2 Calculation ofδ and µ in a Single Cell / 503

11.12.3δ handµ hAre Improved due to the Natural Two-Site Diversity in the

Handoff Region / 504

11.13 Soft Handoffs / 505

12.1 Adjusting the Parameters of a System / 509

12.1.1 Increasing the Coverage for a Noise-Limited

System / 509

12.1.2 Reducing the Interference / 511

12.1.3 Increasing the Traffic Capacity / 512

12.2 Fixed Channel Assignment Schemes / 513

12.2.1 Adjacent-Channel Assignment / 513

12.2.2 Channel Sharing and Borrowing / 513

12.2.3 Sectorization / 514

12.2.4 Underlay-Overlay Arrangement / 515

12.3 Nonfixed Channel Assignment Algorithms / 517

12.3.1 Description of Different Algorithms / 517

12.3.2 Simulation Process and Results / 518

12.7 Small Cells (Microcells) / 536

12.7.1 Installation of a Mastless Antenna / 536

12.7.2 Tailoring a Uniform-Coverage Cell / 537

12.7.3 Vehicle-Locating Methods / 538

12.7.4 Portable Cell Sites / 540

12.7.5 Different Antenna Mountings on the Mobile Unit / 540

13.2 Cellular Analog Switching Equipment / 555

13.2.1 Description of Analog Switching Equipment / 555

13.2.2 Modification of Analog Switching Equipment / 556

13.2.3 Cell-Site Controllers and Hardware / 556

13.3 Cellular Digital Switching Equipment / 558

13.3.1 General Concept / 558

13.3.2 Elements of Switching / 558

13.3.3 5ESS (No 5 Electronic Switching System) / 560

13.3.4 Comparison Between Centralized and Decentralized

Systems / 561

13.4 Packet Switching / 561

13.4.1 General Description / 561

13.4.2 Packet Switches in Mobile Tandem Switching / 561

13.4.3 Packet Switching Protocols and Hardware / 563

13.5 Packet Related Networks / 564

13.5.1 ATM Networks / 564

13.5.2 Soft Switching: Next-Generation Voice Infrastructure / 565

13.6 Special Features for Handling Traffic / 566

13.6.1 Underlay-Overlay Arrangement / 566

13.6.2 Direct Call Retry / 566

13.6.3 Hybrid Systems Using High Sites and Low Sites / 566

13.6.4 Intersystem Handoffs / 567

13.6.5 Queuing Feature / 568

13.6.6 Roamers / 569

13.7 MSO Interconnection / 569

13.7.1 Connection to Wire-Line Network / 569

13.7.2 Connection to a Cell Site / 569

13.8 Small Switching Systems / 571

13.9 System Enhancement / 571

14.1 Data Links / 573

14.2 Available Frequencies for Microwave Links / 574

14.3 Microwave Link Design and Diversity Requirement / 575

14.6.1 Characteristics of Microwave Antennas / 585

14.6.2 Polarization and Space Diversity in Microwave Antennas / 586

14.6.3 Types of Microwave-Link Antenna / 586

14.6.4 Installation of Microwave Antennas / 587

14.7 Optical Data Link / 587

14.7.1 Introduction / 587

14.7.2 Optical Communication Systems / 588

CONTENTS xv

14.7.3 Optical Multiplexing Technique: WDM / 589

14.7.4 High-Speed Optical Data Link Modules / 590

14.8 Point-to-Multipoint (PMP) Wireless Access / 591

14.9 LMDS (Local Multipoint Distribution Services) / 592

14.10 MMDS (Multipoint Microwave Distribution System) / 593

14.11 Cable (Wire) Replacement Devices / 594

14.11.1 Bluetooth (BT) / 594

14.11.2 ZigBee / 595

14.11.3 UWB (Ultrawideband) / 596

14.11.4 IrDA (Infrared Data Association) / 597

14.11.5 RFID (Radio Frequency Identification) / 598

14.11.6 Comparison of the Cable Replacement Devices / 601

15.2.2 Word Error Rate Consideration / 609

15.2.3 Word Error Rate Calculation / 610

15.2.4 Parity Check Bits / 611

15.3 Measurement of Average Received Level and Level Crossings / 614

15.3.1 Calculating Average Signal Strength / 614

15.3.2 Estimating Unbiased Average Noise Levels / 617

15.3.3 Signal-Strength Conversion / 620

15.3.4 Receiver Sensitivity / 620

15.3.5 Level-Crossing Counter / 621

15.4 Spectrum Efficiency Evaluation / 622

15.4.1 Spectrum Efficiency for Analog Cellular Systems / 622

15.4.2 Advantages and Impact of FM / 623

15.4.3 Number of Frequency-Reuse Cells K / 623

15.4.4 Number of Channels per Cell m / 624

15.4.5 Rayleigh Fading Environment / 624

15.4.6 Determination of Cell Size / 626

15.4.7 Considerations of SSB Systems in a Rayleigh Fading Mobile Radio

Environment / 628

15.4.8 Narrowbanding in FM / 630

15.5 Evaluation of Spectrum Efficiency between CDMA and OFDMA / 633

15.6 Handsets (Portable Units) / 634

15.6.1 Technology of Handsets (Portable Units) / 635

15.6.2 Loss Due to Building Penetration / 635

15.6.3 Building Height Effect / 637

15.6.4 Interference Caused by Portable Units / 638

15.6.5 Difference between Mobile Cellular and Portable Cellular

Systems / 638

15.7 Evaluation of Data Services / 641

15.7.1 Requirement for AMPS System / 641

15.7.2 Digital Data Services / 641

15.7.3 Testing / 644

15.8 Comparing WiMAX and 3G (HSDPA) for Mobile Broadband

Wireless / 644

xvi CONTENTS

16.1 Intelligent Cell Concept and Applications / 647

16.1.1 What is the Intelligent Cell? / 647

16.1.2 The Philosophy of Implementing Power-Delivery Intelligent Cells / 647 16.1.3 Power-Delivery Intelligent Cells / 650

16.1.4 Processing-Gain Intelligent Cells (K → 1 System) / 657

16.1.5 Summary of Intelligent Cell Approaches / 661

16.2 Applications of Intelligent Microcell Systems / 664

16.2.1 Description of the Intelligent Microcell Operation / 664

16.2.2 Applications to Increasing Capacity / 668

16.2.3 Applications of Coverage Provision / 669

16.3 In-Building Communication / 674

16.3.1 Differences between Ground Mobile and In-Building Design / 674

16.3.2 Natural In-Building Radio Environment / 674

16.3.3 A New In-Building Communication System / 675

16.3.4 In-Building System Configuration / 676

16.3.5 A PCS Application / 677

16.4 CDMA Cellular Radio Network / 679

16.4.1 System Design Philosophy / 679

16.4.2 Key Elements in Designing a CDMA System / 680

16.4.3 Uniform Cell Scenario / 681

16.4.4 Nonuniform Cell Scenario / 685

16.5 MIMO (Multiple Input–Multiple Output) / 691

16.5.1 Introduction / 691

16.5.2 Description of Technology / 692

16.5.3 MIMO Capacity / 693

17.1 Advanced Intelligent Network (AIN) / 697

17.1.1 Intelligent Network Evolution / 697

17.2.5 SONET and ATM / 702

17.3 Ain for Mobile Communication / 703

17.4 Asynchronous Transfer Mode (ATM) Technology / 705

17.5.4 IP Packet Format and IP Addressing / 711

17.5.5 Addressing in the Internet / 714

17.5.6 Security on the Internet / 715

17.8 Mesh Network/Ad Hoc Network / 720

17.8.1 Radio Structure of Ad Hoc Mesh / 720

17.8.2 MAC Layer of Ad Hoc Network / 720

17.8.3 Protocols for Mesh and Ad Hoc Networks / 722

17.8.4 ODMA (Opportunity Driven Multiple Access) / 722

17.8.5 Mesh Network Attributes / 723

17.8.6 Wireless Sensor Network (WSN) Attributes / 724

17.9 Wireless Information Superhighway / 725

17.9.1 An Example for Applying the Last 50 Meters / 728

18.3 Complementary Code Keying (CCK) Codes and Modulation / 739

18.4 Turbo Codes and LDPC / 743

18.4.1 Turbo Code / 743

18.4.2 LDPC (Low Density Parity Check) Code / 744

18.5 Study of A 60-GHz Cellular System / 747

18.5.1 Propagation in the Scattered Environment / 747

18.6.2 Comparison of Two Signal Attenuations from Their PDC Curves / 751

18.7 MVNO and MVNE / 753

18.7.1 MVNO (Mobile Virtual Network Operator) / 753

18.7.2 MVNE (Mobile Virtual Network Enabler) / 754

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When I started revising the second edition of Wireless Telecommunication to create the

current edition, I faced some difficulties First, I did not know which parts of the bookshould be saved if dictated by reader preferences over the past ten years

Second, during the last ten years, so many new technologies and systems were developedthat it became difficult to decide what new information to include and how to include it in asuccinct fashion; I have therefore tried to present the best of both worlds: to cover as much

as I can while, keeping the size of the book as manageable as I feel the second edition was

It took me almost two years to revise this book, and from those two years’ work emerged

a book that I feel can be useful to readers on the following fronts:

ras a textbook as well as a handbook, since it covers new systems and technologies.

ras a guide to broadband wireless access and cellular systems.

ras a reference book for executives.

ras a textbook for college seniors and graduate students.

There are many new chapters (Chapter 1, Chapters 5–7, and most of Chapter 18), and Ihave added a great deal of new material to existing chapters concerning current topics such

as MIMO, AdHoc/Mesh Networks, LDPC codes, RFID, etc

For reference sake, the chapters of this books can be divided into the following areas:Chapter 1 Introduction to wireless communications

Chapter 2 Basic principles

Chapters 3–6 Cellular systems from first generation to third generation

Chapter 7 Broadband wireless access

Chapters 8–15 System design and deployment

Chapters 16–18 New ways of achieving broadband wireless access

Also, there are so many wireless communication acronyms that it is hard to expect readersmemorize them To make it simpler, this book divides the acronyms into three parts: gen-eral terms of telecommunications, cellular communication terms, and, broadband wirelessaccess terms

The Internet is obviously a good place to gather a great deal of information However,

tech-nical books such as Wireless Telecommunication pull many pieces of information together

and provide a range of general topics that readers can then understand as a whole This

is why the Internet cannot replace textbooks and why I believe textbooks will remain avaluable source of information in the future

As I recall, I finished writing the first edition of Wireless Telecommunication in 1986,

but the manuscript was evaluated by McGraw-Hill for almost a year before it enteredproduction The reason for the delay was that McGraw wondered if readers would actually

be interested in learning about cellular systems I’m happy to say that with the publication

of this third edition, the answer was clearly yes

xix

Copyright © 2006, 1995, 1988 by The McGraw-Hill Companies, Inc

Click here for terms of use

xx PREFACE

When the first edition was published in late 1988, it was still the only book availableworldwide on the topic of cellular communications Before long, I was receiving compli-ments on the book—how one reader read the book to prepare for an industry job (in thisbrand-new industry) and landed the position, how informative another reader found thebook, etc But I also receive other compliments as “I always carry this book because thebook fits well in my briefcase”, or “I like to read the book because it is light and easy tocarry.” I know those readers really spoke from their heart I thanked them from my heart.The third edition, while a bit longer, a bit heavier, can still be pocketed, yet containingeven more updated information on wireless telecommunication technology—and can beglanced at just before a job interview to another brand new field today named broadbandwireless access (BWA) which will create its new and growing market and probably willevolve toward 4G era in the future Good luck to those readers

William C Y Lee

PREFACE TO THE FIRST

EDITION

As the number of cellular subscribers increases, the interference that will be experienced bythe systems will also increase This means that many large cellular systems will, sooner orlater, have to handle interference problems This is a lucrative field that is ripe for researchand that will soon be begging for more advanced applications

This all-inclusive and self-contained work, consisting of fifteen chapters, is a basictextbook that supports further exploration in a new communications field, cellular com-munications Since it is the first in its field, this book may be considered a handbook orbuilding block for future research

For years it has been my desire to write a book on the technical aspects of cellular systems.Since it is a new field, the theory has to be developed and then verified by experiment I am

seeking to adhere to the progression of learning that I described in Who’s Who in America:

1 Use mathematics to solve problems.

2 Use physics to interpret results.

3 Use experiments and counterexamples to check outcomes.

4 Use pictures to emphasize important points.

Since I have accumulated many pictures in my mind, I would like to share them with

my readers In this field many new applications and theories have been discovered Thus,

my findings will help the reader to assimilate this new knowledge and accelerate learningtime The many mistakes that have been made in the past in designing cellular systemscan now be avoided Engineers who work in other communication systems will appreciatethe many diverse concepts used in cellular systems The reader should be aware that it ispossible to apply the various theories improperly and thereby create many serious problems

I would like to hear from readers about their cellular systems experiences, both successfuland unsuccessful

Overall, I have written this book for technical engineers who would like to explore

options in the cellular industry However, Chapters 1 and 2 are for executives and for

anyone who would like to familiarize himself or herself with key concepts of the field.Chapter 3 describes the specification of cellular systems The North American specificationworks in Canada, the United States, and Mexico, so a cellular phone will work anywhere

in this territory because of the standardized specification

Chapter 4 introduces the point-to-point model I developed over the last 15 years Itcan be used as a core to develop many design tools Chapters 5 and 6 deal with cochan-nel interference problems, and Chapter 7 deals with noncochannel interference problems.Chapters 8 through 13 offer detailed material for engineers to solve problems concerningimproved system performance Chapter 14 describes the digital systems which may becomethe next-generation cellular systems, and presents many key issues in order to alert readers

xxi

Copyright © 2006, 1995, 1988 by The McGraw-Hill Companies, Inc

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xxii PREFACE TO THE FIRST EDITION

to possible future developments Chapter 15 highlights some miscellaneous topics related

In the last six years, I have taught 3-day seminars sponsored by George WashingtonUniversity I am trying to convince the cellular industry that if we have narrow-mindedattitudes and do not share our experiments or knowledge, the whole industry will not advancefast enough and could be replaced by other new industries, such as wireless communications

or in-building communications

Let us join together to allow the cellular industry its optimum potential and set our goalthat one day a pocket cellular phone will carry our calls to any place in the world

William C Y Lee

First, I have to thank my mentor, Chap Cutler, who gave me valuable guidance throughout

my career and who advised me to revise this book Unfortunately, I could not finish it before

he passed away I owe him a great deal

I am deeply thankful to my colleagues at Vodafone-AirTouch, and LinkAir cations who helped me in the past, especially Ting Zheng, who has given me full support towork on my book I am also thankful to David J Y Lee, my first Ph.D student, who helped

Communi-me draft Chapter 7 and reviewed several chapters

I am also obliged to my dear assistant, Kathy Gardner, who has been so patient in readingand editing my sloppy writing, written on paper pads, while I was traveling or out of myoffice This book could not have been completed without her help

I have to thank Steve Chapman of McGraw-Hill, who constantly encouraged me, andStephanie Lentz of TechBooks, for the tedious proofreading and schedule keeping and fordoing what I requested of her with great patience

Finally, I have to thank my lovely wife Margaret for her understanding over these years

in giving me the time to write books I hope this book can inspire my grandson, Alex,although he is only one year old now

xxiii

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WIRELESS AND

CELLULAR

TELECOMMUNICATIONS

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CHAPTER 1 TREND OF MOBILE

WIRELESS

In order to classify in this book the generations for mobile cellular development, it may

be logical to use the multiple access schemes The analog frequency division multiple cess (FDMA) systems are 1G systems The digital time division multiple access (TDMA)systems with circui switching are 2G systems The code division multiple access (CDMA)systems with packet/circuit switching are 3G systems, and some different advanced mo-bile access technology used with an all Internet protocol (IP) network will be called 4G.However, because each technology itself is advanced with time, we use time periods toclassify the generations Those, analog systems are 1G, digital voice systems are 2G, dig-ital voice/data systems are B2G, and broadband digital systems are 3G Wireless localarea network/wireless metropolitan area network (WLAN/WMAN) are B3G systems, andvery-high-speed data-rate systems are 4G systems

ac-1.1.1 AMPS System (First-Generation System)

In 1964, Bell Laboratories formed a mobile communication department after the U.S.Congress took away the satellite communications business from AT&T The early wirelessnetworks only concentrated on voice communication In the beginning, the analog systemsnamed HCMTS (high-capacity mobile telephone system) were developed at Bell Labs inthe period 1964–1974 The HCMTS used an FM modulation with a bandwidth of 30 kHzfor both signaling and voice channels The FM modulation index for voice is 4 which is theratio of the frequency deviation (12 kHz) and the voice frequency (3 kHz) The signaling rate

is 10 kbps The system also migrated new handoff features At that time, there was no dard organization for wireless mobile systems AT&T made its standard for HCMTS1thefirst-generation cellular system Later, the standard EIA (Electronic Industrial Association)named the system IS-3 (Interim Standard 3) EIA merged with TIA (TelecommunicationIndustrial Association) and was then called TIA-EIA The new name for the system, AMPS(Advanced Mobile Phone Service),2 −5was used since 1976, and the system was deployed

stan-in 1984 Bell Labs stan-in 1975 awarded OKI a contract to manufacture the first 200 mobilephones (car phones), as AT&T could not be permitted to manufacture the car phones ac-cording to the FCC’s ruling Then next year, a total of 1800 car phones were awarded toOKI, E.F Johnson, and Motorola—each manufactured 600 car phones Bell Labs built carphone testing equipment All the phones made by the three companies had to pass the test,which none passed the first time The world’s first 2000 car phones were used in the ChicagoTrial in 1977 The system specification was finalized after the trial The U.S cellular systemcould not commercialize until the FCC divided the allocated 20-MHz cellular spectrums

1

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2 CHAPTER ONE

into two: one 10 MHz went to telephone companies (wirelines) called Band B and the other

10 MHz went to paging/dispatch companies (non-wireline) called Band A, and the Band Bsystem began deployment in 1984 The specification of AMPS is described in Chapter 3.Therefore, Japan NTT (Nippon Telephone and Telegraph Co.) deployed its version ofAMPS in Tokyo in 1979, which was the first commercial system in the world The NTTsystems had no diversity scheme at the base, and the signaling used was multitone signaling

at a rate of 300 tones/s The service cost was high, and the voice quality was unsatisfactory.After AMPS deployed in the United States, the voice quality was outstanding, and theservice cost was much lower than the NTT system Then, the United Kingdom modified theAMPS system with a channel bandwidth of 25 kHz, called Total Access CommunicationSystem (TACS) Besides, the Nordic Mobile Telephone (NMT) majority deployed in fourNordic countries; the system C450 in Germany and cordless phone 2 (CT2) in the UnitedKingdom were also served in the market, but they were not cellular systems Because thetechnology in the 1980s could not make a handset phone, the analog AMPS systems weredesigned and used as car phones, and the car battery supplied the power The coverage foreach cell was around an area of 8 miles radius

1.1.2 Second-Generation System

In 1983, Europe started to develop GSM6−9(the original name was called Group of SpecialMobile, then was changed to Global System for Mobile) GSM is a digital TDMA systemand was first deployed in Germany in 1991 It was the first digital mobile cellular system

in the world The specification of GSM is described in Section 4.2

In 1987, due to the fast-growing number of subscribers, the capacity of AMPS became

an issue Then, the North American TDMA (NA-TDMA) was voted as a digital standard

in 1988 for trying to solve the capacity issue The specification of NA-TDMA is appeared

in Section 4.3 However, TDMA technology might not be the right choice for future needs

In 1989, Qualcomm was starting to develop CDMA with great assistance from PacTel

in financial, technical, and spectrum issues; the CDMA system could have a capacitythat was 10 times more than AMPS according to theoretical analysis at that time Toprove the technology, PacTel in 1990 migrated its 1.25 MHz (40 AMPS channels) from12.5-MHz spectrum bandwidth in 800 MHz for trialing a CDMA system in the San Diegomarket At that time, performance of the analog systems in San Diego suffered because

of the CDMA trial Nevertheless, PacTel believed that a new technology was needed forthe future In 1993, after the U.S market reached 1 million analog mobile subscribers, thishigh-capacity CDMA digital system10 −12was born The system is described in Section 4.4.

In 1994, PacTel’s name was changed to AirTouch AirTouch pursued the deployment of itscommercial CDMA systems

In 1989, the United Kingdom had released the PCN (Personal Communications works) licensed band in 1900 MHz and awarded four licenses through a beauty contest.Later, PCN adopted the GSM system Also, the 900-MHz spectrum of the TACS band wasmigrated to GSM as well In 2000, GSM had a data transmission enhancement called GPRS(General Packet Radio Service), which could use any number of time slots among the totaleight slots for sending data The data rate is from 14.4 kbps to 64 kbps There is anotherhigh-speed data enhancement called EDGE (Enhanced Data Rates for GSM Evolution),which modulations are changed from GMSK (Gaussian minimum shift keying) to 8 PSK(phase shift keying) The transmission data rate can be up to 500 kbps The EDGE is de-scribed in Sec 5.2 In 1990, Japan had developed its PDC (Personal Digital Cellular).13The 12.5-kHz offset the 25-kHz channels, thus the number of channels were increased inthe system It is a TDMA cellular system operating at 800 MHz and 1.5 GHz The structure

Net-of PDC is very similar to that Net-of NA-TDMA, and is described in section 4.5.2

TREND OF MOBILE WIRELESS 3

In 1995, the CDMA IS-95 was the first CDMA system (later called cdmaOne in 1998)using 1.25-MHz bandwidth It was suggested by PacTel that the operator could give upone tenth of the spectrum from analog spectrum to create a CDMA channel and generate

at least twice the capacity of the entire analog system for voice The CDMA systems werecommercialized in Hong Kong, Los Angeles, and Seattle almost at the same time in early

1995 However, those systems themselves were not fully developed at that time

In 1996, the Korean market demonstrated the merit of the CDMA system From January

1996 to September 1996, the number of subscribers went from zero to 1 million in 9 months.The Korean CDMA systems observed their expected high capacity In 1999, cdma1X wasdeveloped It can have a data rate up to 64 kbps (see Section 5.6) In 2000, cdma1X created

an EVDO (Enhanced Version of Data Only) option14 −15 It was using a 1.25-MHz channeldedicated for data only It can transmit 2 Mbps while the terminal is nomadical and 384 kbpswhile in motion The TDM scheme is used in the EVDO Then, in 2004, EVDV (EnhancedVersion for Data and Voice) became another option to implement on a 1.25-MHz channel

to have 2 Mbps data plus voice EVDO and EVDV are sometimes called CDMA2000 1Xsystems Both EVDO and EVDV are described in Section 6.8

1.1.3 3G Systems

In 1997, 3G (third generation) had been suggested mainly by DoCoMo and Ericssonand cdmaOne was called 2.5G At that time, all the system providers around the worlddid not ask for 3G but were told by the vendors to prepare for the future

In 1998, there were 13 proposals submitted to ITU Three of them were chosen by OHG(Operator Harmonization Group) for ITU Wideband CDMA WCDMA,14CDMA2000,15and UTRA-TDD (UMTS Terrestrial Radio Access -TDD TD-SCDMA (Time Division-Synchrous CDMA) are all 5-MHz bandwidth channels Ericsson and DoCoMo mainlydeveloped WCDMA The carrier bandwidth is 5 MHz and the chip rate is 3.84 Mcps Oneversion of 3G systems, called FOMA (Freedom of Mobile Multimedia Access), has beendeployed in Japan FOMA’s handsets can have a higher data rate and be operated in theWCDMA system but not the other way around CDMA200015has been developed fromcdma1X with a channel bandwidth of 1.25 MHz and a chip rate of 1.2288 Mcps and be-comes cdma3X with a bandwidth of 3.75 MHz and a chip rate of 3.68 Mcps cdma3X is amulticarrier CDMA system Its downlink is 3× 1.25 MHz, and its uplink is a wideband 3.75MHz WCDMA and CDMA2000 are using frequency division duplexing (FDD) spectrum.The 3G systems, UTRA-TDD/TD-SCDMA, are using time division duplexing (TDD) spec-trum implementing multicode, multislot, and orthogonal variable spreading factor (OVSF)technologies UTRA-TDD developed in Europe with its bandwidth of 5 MHz and carrierchip rate of 3.84 Mcps TD-SCDMA, developed in China, had a channel bandwidth of 1.6MHz and a carrier chip rate of 1.2288 Mcps TD-SCDMA can be used as a multicarrier(3×) CDMA system All 36 systems are described in chapter 6

To choose a channel bandwidth of 5 MHz for WCDMA creates difficulty in ing a CDMA radio channel First, the bandwidth of 5 MHz had not been studied in-depth

design-to determine whether it was an optimum bandwidth for mobile cellular before ing it Second, many multipaths were unexpectedly received in a 5-MHz bandwidth thanthat received by the conventional CDMA system with a bandwidth of 1.25 MHz Thus,more studies were needed to understand the multipath phenomenon in a bandwidth of 5MHz Therefore, the delay in developing the WCDMA system was not avoidable Since

choos-2000, the postponement of deploying the WCDMA system continued year after year Inthe United Kingdom, the 3G spectrum licenses were auctioned in 1999 and awarded in

2000 to four system providers Vodafone was one of the four system providers Vodafonebet US 10 billion in order to win the license for a 30-MHz (2× 15 MHz) nationwide

on user’s demands as the fourth-generation (4G) cellular system Many rich applicationsneed high-speed data rates to achieve them.

ITU in July 2003, had made a requirement for 4G system as follows:16

1 At a standstill condition, the transmission data rate should be 1 Gbps.

2 At a moving condition, the transmission data rate should be 100 Mbps.

Any proposed system that can meet these requirements with less bandwidth and highermobile speed will be considered It is a beauty contest With this high-speed data system,many advanced applications for the users can be realized A potential 4G system could beused in the family of OFDM (Orthogonal Frequency Division Multiplexing), because theWMAN described in Section 7.4.2 using OFDM can have a transmission data rate of 54–

70 Mbps, which is much higher than the CDMA system can provide The 4G perspectivesystems using OFDM are described in Chapter 18

1.1.5 Other Cellular–Like Systems

In 1989, the United Kingdom had developed a cordless phone called CT-2 system.17 Itwas the first digital mobile radio system to use handsets The total spectrum bandwidth is

4 MHz in 800 MHz The channel access is FDMA/TDD The channel bandwidth is 100-kHzspacing, thus there are 40 channels The two-way conversation can be sent out but cannot

be received, just like a portable telephone booth The United Kingdom has issued the CT-2system to four operators for the reason of fair competition Each operator can provide manyphone zones, and each one has 10 channels to serve its subsidiaries Because there was nocoordination in radio operation among the operators and, also because the phone zones ofeach operator were not properly located, the radio interference problem among the four oper-ators could not be solved Ericsson had developed an upgrade system from the CT-2 version,originally called DCT900, and then changed to CT-3.18Its channel bandwidth was 1 MHzwith 64 time slots Overall data rate was 640 kbps CT3 did not really deploy into mobilemarkets but was used for fixed wireless application with PBX (Private Branch Exchange).DECT (Digital European Cordless Telecommunication System)19is a European standardsystem It is also a CT2-like system operating at 1.8 GHz and its channel bandwidth is 1.728MHz It is a TDD system with 12 slots; 6 time slots for downlink and 6 for uplink It usedthe public network to have mobile communication within the home or to provide businesscommunication locally and mainly provide wireless local loops DECT was deployed inregional areas in Europe as described in Section 4.5

PHS (Personal Handy Phone)20is a TDD system operating at 1.9 GHz and supportingpersonal communication services; the channel bandwidth is 300 kHz There are eight timeslots in each channel Among all the PHS channels, some slots are sending, some slotsreceiving at the same time In 1995, there were four PHS operators in Japan The number

of subscribers reached 7 million, but none of them were making profit Finally, DoCoMoconsolidated with the other three, using the wireline switches instead of mobile phoneswitches, and started to survive the PHS business In 1999, PHS went to China, called

TREND OF MOBILE WIRELESS 5

by the nickname “Little Smarter,” used by two wireline companies to serve customers forcellular-like systems In 2003, the PHS subscribers already reached 20 million in China andbecame a threat to the cellular system providers PHS is described in Section 5.5

In the 1980s, the specialized mobile radio (SMR) bands were issued to the trunkingradio Every license is allowed have 200 kHz in 900-MHz bands and needs to have 100subscribers in 2 years to continue the license Motorola acquired most SMR bands in the1990s and developed its proprietary system called MIRS (Mobile Integrated Radio System),and then changed the name to iDEN (Integrated Digital Enhanced Network) described inSection 5.4 It is a TDMA/FDD system with a channel bandwidth of 25 kHz at 850 MHz.The number of time slots is six; usually, three time slots are always inactive The modulation

is 16 QAM (Quadrature amplitude modulation) Its digital system is a cellular-like systemmainly for voice At the beginning, its voice quality was not as good as cellular systems Thesystem started to provide many good features by using Nortel’s switch and was the first one

in year 2001 to have a push-to-talk feature The push-to-talk can have a virtual connection

in real-time to connect a group of party members online after pushing the buttons Thus, thecaller doesn’t need to dial the phone number of every party member It can be treated as aconference call to a group of people Other cellular system providers adopted this attractivefeature Nextel is using nonauction spectrum Therefore, the system is a nonstandard system

A wireless PAN network can use Bluetooth, developed by Ericsson in 1978 Bluetoothwas named after a pirate king in the Nordic countries It is used for short distances up to

10 feet The channel bandwidth is 200 kHz using QAM modulation The data rate can be

1 Mbps It is a short wire replacement for wireless Today, most cell phones are equippedwith Bluetooth The Zigbee was developed from the IEEE 802.15 standard in the UnitedStates It can have a range of 30 m, but the data rate is about 144 kbps It can be used as anetworking video Devices used in PAN are described in Section 14.11

In the 1990s, WLANs was divided into the radio-frequency (RF) systems and infrared(IR) systems specified by the FCC The RF systems are subdivided into the licensed non-spread-spectrum (NSS) and the unlicensed spread spectrum (SS) In the unlicensed SS, itrequires a minimum of 50 and 75 hopping frequency at 910 MHz and 2.5 GHz, respectively,

or achieved by a spread-spectrum modulation exceeding a spreading factor of 10 in directsequence systems

The wavelength of IR is slightly longer than the wavelength of visible light It is usedfor data communications in wireless LANs; to download data among PCs, PDAs, and cellphones IR links are limited to distances under 15 m There is a diffuse IR, that does notrequire a line-of-sight path between transmitter and receiver But it is suitable for fixedlinks, not for nomadic A standard point-to-point infrared at a 1–2 m range can have up to

4 Mbps Infrared can download data fast and have little or no interference

6 CHAPTER ONE

1.2.2 Wireless LAN Standards

Standardization activities on wireless LAN are the key to spread the use of its application.They are concentrated mostly on the unlicensed bands Two major approaches are used toregulate the unlicensed bands: one is an interoperable rule among all equipment, the other

is spectrum etiquette (i.e., enables wireless LAN equipment manufactured by differentvendors to fairly share the wireless resources)

The European Telecommunications Standards Institute (ETSI) has defined awireless standard called HIPERLAN to provide 23.5 Mbps in the 5-MHz band,and the FCC allocated 2.4 GHz and 5.8 GHz for IEEE 802.11 a/b/g:

The HIPERLAN can be used as a wireless MAN (called HIPERMAN), so HIPERMAN

is very similar to IEEE 802.11 a/b/g The IEEE 802.11 a/b/g will be described in Chapter 7

1.2.3 Wireless WAN Evolution

As the data rate of using the broadband medium becomes popular, a user can use any less LAN device whether in a building, in an airport, or at a hot spot In the 1980s, existingwireless wide area networks (WWAN) were Mobitex’s RAM mobile data, providing 8 kbps,and Motorola’s ARDIS (Advanced Radio Data Information Services), providing 19.2 kbps.IBM has used ARDIS since 1983 to keep in touch with its field servicemen; ARDIS openedfor public use in 1990 Also, Ricochet wireless WAN service was introduced by Metri-com in 1994 using unlicensed (ISM) band over a typical range of 0.25 km to 0.75 km.Ricochet access points also can be used as a repeater to send data back to a centralpoint via access points as relays This system can serve 14.4 kbps, but the ratio ofthe number of subscribers and the number of access points is around 3:1 The trafficcongestion was the problem There were 30,000 subscribers of Metricom in San Fran-cisco Metricom also deployed a new Ricochet system in New York with a data rate of28.8 kbps Again, the system was not intelligent enough to resolve the traffic congestionproblems

wire-The CDPD (Cellular Digital Packet Data)22was designed to provide packet data services

as an overlay to the existing analog cellular AMPS network The CDPD will use one ofthe AMPS channels when it is idle and will hop out to another channel when AMPS isstarting to use it Each 30-kHz channel supports 19.2 kbps CDPD used GMSK modulationand frequency hopping techniques Because most cellular systems had foreign interferencedetectors installed at base stations, as soon as a CDPD channel occupied one cellularchannel, the cellular system would not assign that channel for a new call Thus, CDPDchannels reduced the cellular capacity Also, CDPD took too long to develop its system to

be deployed and missed the window of business opportunity

Because the GSM system’s primary purpose was voice service system, the EuropeanETSI in 1992 had developed a public standard for trunked radio and mobile data systemscalled TETRA (Trans European Trunked Radio) usingπ/4-DQPSK (differential binary

TREND OF MOBILE WIRELESS 7

phase shift keying) modulation operating at a channel rate of 3G kbps in each 25-kHzchannel Since GSM became a worldwide system and it needed not only voice but alsodata service Thus a GPRS packet data add-on system was developed, then TETRA hasbecome less valid

For wireless WAN, IEEE 802.16 is developed for LMDS (local multipoint distributionsystem) (23–40 GHz), and IEEE 802.16 a/d/e for MMDS (multichannel multipoint dis-tribution service) (2.4–7 GHz) IEEE 802.16 and IEEE 802.16 a/d are for the fixed linkcondition, and 802.16e is for the mobile condition The range for 802.16 is around 100

m and for 802.16 a/d/e is 5–30 km The IEEE 802.16 is not active because the LMDSmarkets were not ready in 1990 All the 802.11 and 802.16 are using OFDM modulationswith frequency hopping as an option in TDD band IEEE 802.16e can become an OFDMA(Orthogonal Frequency Division Multiple Access) system with an all IP network IEEE802.16e has five proposed technologies, and one of them is OFDM In 2004, the companieswho endorsed OFDM technology formed an appliance called WiMAX, with this effort led

by Intel WiMAX system can use VoIP (Voice over IP) for voice and transmit 54 Mbps over

a bandwidth of 20 MHz The frequency spectrum is at the unlicensed band of 5.8 GHz TheWiMAX chip will be embedded in all notebooks or PCs by the year 2006, and a WiMAXphone will be made by the year 2007 as predicted There is another standard wireless WANsystem called IEEE 802.20, led by Flarion Flarion’s system is using OFDMA in FDD bandswith frequency hopping called Flash OFDM system It can implement handoffs for mobileunits while crossing the cells as a cellular-like system However, Flarion’s system has notyet been a standard system in IEEE 802.20 The description of IEEE 802.20 is appeared inSection 7.4.4

1.3.1 History

In 1945, A.C Clarke suggested that if a satellite were at a height of 35,880 km above theEquator, it would orbit Earth every 24 hours and appear stationary over a fixed point abovethe Equator Three satellites could cover the whole Earth’s surface except at the areas nearthe poles.25A passive balloon called Echo, developed by Bell Labs in conjunction withJPL, was launched in 1960 in a low orbit of 500 km It was a passive satellite In July

1962, Telstar was launched into an elliptical orbit with its altitude varying between 950 and

5700 km Telstar, an active satellite, receives the earth signal at 6390 MHz and retransmits

at 4170 MHz with a power of 2 W The Relay satellite was launched in December 1962into an inclined orbit The uplink frequency is 2000 MHz, and the downlink frequency is

4170 MHz The first experimental Syncom satellite was launched in 1963 and was the firstnear-synchronous-orbit satellite In August 1962, the U.S Congress expressed willingness

to establish a global communication satellite system and thereby created INTELSAT26(International Telecommunication Satellite Consortium) Early Bird, known as Intelsat I,was launched in 1965 The four Intelsat series launched in different years with increasingchannel capacity are listed in Table 1.1 The uplink frequency and downlink frequencyare 6 and 4 GHz, respectively, in all four Intelsat series The Russian communicationsatellite Molniya I was launched in 1965 into an elliptical orbit in which the orbit time is

12 hours The orbit was inclined so that the satellite would appear over a point on Earth

at the same local time each day in Russia Then, a number of Molniya satellites provided

a television distribution system known as the Orbital system, covering the whole SovietUnion Global communications are often based on the satellite systems to establish globalcoverage

TABLE 1.1 Communication Satellite Characteristics

TREND OF MOBILE WIRELESS 9 1.3.2 Attributes

In the satellite communication systems, by choosing the satellite orbit, the communicationbetween any two points, “visible” from the satellite over a planned area, observes differenttransmission delays because receiving a call from a stationary satellite is 250 ms round trip.The low earth orbit (LEO) satellites are close to the earth, and can shorten the transmissiondelay to 50 ms, but the LEO satellites travel around the earth every 2 hours or less Thetime for a ground user to last a call from a LEO satellite is only a few minutes In order

to keep the call continue, the call needs to be passed from one satellite to another Anyparticular LEO only carries a piece of data or call segments from the sender to the receiver

In satellite communications, a near-zero Doppler effect in the receiving signal is a significantadvantage The choice of frequency is important: When the frequency is below 5 GHz, thesignal is affected by galactic noise and disturbed Sun noise In satellite communications,using two linear polarized waves to send two different pieces of data can increase thespectral efficiency However, Faraday rotation effects occur between two linear polarizedwaves and degrade the signal quality Faraday rotation effects are negligible above 10GHz Also, ionosphere scintillations are caused by the fluctuations of the electron density

in the sporadic E layer and F layer due to geographical location and season of the year.The ionosphere scintillations are negligible also at gigahertz frequencies Above 10 GHz,the signal attenuation due to water vapor or rain clouds, in the space can increase in skynoise temperature In most cases, the diversity schemes and depolarization solution areapplied to reduce the undesired natural phenomenon effect on the received signal

1.3.3 Satellites in Different Orbits

The satellite systems, because of the high altitude, can establish global coverage The firstpublic communication by satellite took place in 1962, after Echo and Telstar experimentswere successfully done by AT&T Bell Labs Comsat Communication, Inc., was formed,and the early work was based on the National Aeronautics and Space Administration(NASA) applications technology satellite program (ATS) Satellite systems can providewireless mobile communications The actual footprint size on Earth depends on the orbit

of the satellite above Earth

1 A geostationary earth orbit (GEO) satellite is in orbit 36,000 km above Earth and moves

along the orbit with the same speed as the rotation of Earth Thus, the GEO satellite stays

at one spot as seen from Earth GEO has a field-of-view (FOV) diameter of approximately13,000 km It can cover most of one country GEO is a regional satellite It can havemultiple spot beams and can have frequency reuse through small spot beams GEO has

an advantage of being able to maintain a connection with a node but a disadvantage of

a signal’s round trip delay of approximately 250 ms Users will notice a delay whenmaking phone calls or using real-time video

2 A medium earth orbit (MEO) satellite is in orbit at approximately 10,000 km above Earth

and has a FOV diameter of approximately 7000 km It is used in a group of MEO satellites

to have the footprints cover the important regions around the world, as the MEO satelliteorbits the world every 12 hours, such as Global Positioning System (GPS) satellites.There are 24 GPS satellites among them, 18 are active and 6 for spares GPS covers theentire world At any one time, one spot on Earth can see three GPS satellites above Earth

to determine the location of that spot There are two kinds of codes: P code for U.S.military use and C code for commercial use worldwide Since 2003, GPS navigationsystems have been installed in many cars and in cell phones Its location accuracy iswithin 3 m However, GPS can be used only outside of buildings If assisted by othertechnologies, GPS can also be used inside buildings

10 CHAPTER ONE

Odyssey is a MEO satellite system.25It has only 16 satellites and covers the entireworld The cost of this system should be less expensive The life span of the satellitescan be 10 years or longer

Inmarsat’s ICO (Intermedia Circular Orbit)26is also an MEO It has 8 satellites andserves for data transmission only

3 A low earth orbit (LEO) satellite is a low-altitude-orbit satellite and is in orbit at

ap-proximately 800 km above Earth It has a FOV diameter of about 1500 km The FOVarea of each LEO satellite travels around Earth about every 2 hours The concept ofdeploying a cellular communication system using LEO satellites is different from theterrestrial cellular systems The cells are moving and the ground mobile (terminal) sees

a satellite only for a few minutes; then, the connection must be handed over to the nextsatellite The short coverage area changing in time results in frequent handovers in aLEO system Handovers do introduce inefficiencies in system capacity and may dropconnections From LEO satellite to Earth, a delay time of only 5 ms round trip is obtained

as compared with the delay time of 250 ms round trip from GEO satellites

The LEO has many advantages:

(a) A delay time of 5 ms can be achieved;

(b) A smaller path loss is obtained due to the line-of-sight condition, so that Earth

antennas can be smaller and lighter;

(c) Broader coverage is provided than terrestrial systems LEO also uses spot beams

for frequency reuse like terrestrial cellular systems;

(d) Fewer base stations (i.e., satellites) are needed; and

(e) Land, sea, and air can be covered.

However, the LEO has several disadvantages:

(a) The satellite signal is too weak to penetrate the walls of buildings; the wired or

wireless LANs can help extend the satellite’s coverage indoors

(b) The LEO operates at above 10 GHz, and rain attenuation effects on the signal is

another big concern

LEO satellite systems are Motorola’s Iridium,27Loral and Qualcomm’s GlobalStar,28and Teledesic Corporation’s Teledesic

rIridium:27a global satellite phone system for voice and data traffic with a 2400 bps datamodem It was a constellation of 77 LEO satellites and decreased its number to 66 inorder to reduce the construction cost Launched in 1997, it entered commercial service in

1998 at an altitude of 778 km It uses switches on the satellites; the signal can pass fromone satellite to another in space and come down to Earth after reaching a proper satellitefor its destination Because the Iridium system is more expensive to use than the cellularsystems, it could not compete with them It will become a backup system in areas ofthe world, such as oceans or mountains, where cellular can hardly be deployed Iridiumsatellites are interconnected via microwave links and interface via gateways with PSTN(Public Switched Telephone Network) Because of the networking in the sky is throughswitches in the satellites, fewer ground gateways are needed

rGlobalStar28is also a LEO satellite system It is a simple and low-cost system It has

48 satellites at an altitude of 648 km All the satellites are repeaters (transponders) Thesignal received by a certain satellite from a ground terminal has to send back down to aground gateway Therefore, more ground gateways are needed Furthermore the life span

of LEO satellites in orbit is about only 5 years on average

TREND OF MOBILE WIRELESS 11

rTeledesic Corporation’s Teledesic satellites were used to build a satellite PSTN network.Originally, 960 satellites were planned, which number was dropped down to 240 due tothe high investment cost This system was never deployed and does not exist

rThe LEO satellite systems such as Iridium, GlobalStar, and Teledesics did not have a soundbusiness strategy to either compete with or enhance cellular as they originally plannedand as they were struggling to survive Because the cellular service charge had droppeddrastically year after year, the LEO system’s service charge was too high compared tocellular None of the LEO satellite systems were served to the commercial

is the most spectrally efficient system Also, the paging frequencies operate at around 35MHz, 150 MHz, 450 MHz, and 900 MHz In these low-frequency ranges, the propagationloss is minimal compared to the operation system with frequencies above 1 GHz.There are several kinds of paging systems based on their air interfaces.29The British PostOffice initiated one signal format called the Post Office Code Standardization AdvisoryGroup (POCSAG) during 1970 In early 1990, a high-speed protocol called EuropeanRadio Message System (ERMES) was approved by ETSI Motorola developed FLEX,and Philips Telecom developed Advanced Paging Operations Code (APOC) Therefore,different types of pagers receive different signal formats

The POCSAG coding format can be operated at 2400 bps and can accommodate

2 million pagers The FLEX coding format also can be operated at 2400 bps The ERMEScan have an effective transmission rate of 3750 bps

In the 1990s, the paging system was very popular, especially in the Asian region Manypeople carried pagers because of its low service charge Also, the pagers were smaller in sizeand lighter in weight as compared with cellular phones Motorola was developing ReFLEXtwo-way paging systems but could not find a market In the year 2000s, the size, weight,and service charge of cellular phones were drastically reduced, and the need of a pagingsystem did not exist The paging systems disappeared

1.5.1 International Standard Bodies

The International Telecommunication Union (ITU), formerly known as the ConsultativeCommittee for International Telephone and Telegraph (CCITT), has developed standardsfor modem over voice lines The standards association of the Institute of Electrical andElectronics Engineers (IEEE-SA) and International Standards Organization (ISO), two in-ternational standards organizations, have developed local area network (LAN)

system aspects

SG 2Services, numbering andidentities, traffic performance

SG 4Management

SG 7Security

SG 11Signaling and protocolsLead SG

SG 16Encoding, compression,multiplexing

FIGURE 1.1 IMT-2000 standardization structure in ITU.

Some organizations are not standards bodies but are promoting their interested standardsand influence the standards bodies

rITU was formed in 1865, with its headquarters in Geneva, Switzerland It establishesregulations on international use of telegraph, telephone, and radio and satellite commu-nication services In the past, the mobile cellular systems were not standardized by ITUuntil 3G, which were then called IMT-2000 Also, ITU has its functions in managingradio transmission technology (RTT) evaluation process and 3G spectrum allocations.The telecommunication standardization in ITU is divided into two sectors: Radio com-munication section (ITU-R) and Telecommunication Standardization Section (ITU-T) asshown in Fig 1.1 In ITU-R, the task group TG8/1 is responsible for 3G The IntersectorCoordination Group (ICG) is coordinating the IMT-2000 radio and network standards

rIEEE standard association (IEEE-SA) is a leading developer of global industry standards

in a broad range of industries; one area is in telecommunications

IEEE-802 is a program to work on local and metropolitan networks The working groupsrelated to wireless local and metropolitan area networks are

802.11–Wireless LAN working group: WiFi alliance is a nonprofit international ation formed in 1999 to certify interoperability of wireless local area network productsbased on IEEE 802.11 a/b/g specifications IEEE 802.11n is working on a high-speeddata rate at 130 Mbps, a fixed wireless network

associ-802.15–Wireless Personal Area Network (WPAN) working group: There are eight ing groups among them; six are TGs (Task Groups) 802.15.1 is Bluetooth standard.802.15.3a is WPAN alternate high rate (20 Mbps or higher) standard for UWB (UltraWideband) 802.15.4 is investigating a low data rate solution with multiyear batterylife and a simple device Zigbee alliance is manufacturing products based on 802.15.4