通信新技术入门 英文版PDF电子书下载

Part 1 Fundamentals 3

1 Basic Concepts 3

Analog and Digital 5

Analog Signals 6

Digital Signals 7

Bauds, Bits, Bytes and Codes—Getting Down to Basics 13

Overview 13

Baud Rate vs. Bits per Second—Electrical Signal Rates vs. Amount of Information Sent 13

Codes—Adding Meaning to Bits 14

A Byte=A Character 15

Bandwidth—Measuring Capacity 15

Narrowband vs. Wideband—Slow and Fast 16

Compression and Multiplexing 17

Compression—Manipulating Data for More Capacity 18

Streaming Media 20

Multiplexing—Let s Share 23

Protocols and Architectures 25

Architectures—A Framework for Multiple Networks to Communicate 26

LANs, MANs and WANs 28

LANs—Local Area Networks 30

LAN and WAN Devices 31

Home LANs—Sharing Printers and High-Speed Internet Access—A Lack of Technical Support 36

MANs—Metropolitan Area Networks 38

WANs—Wide Area Networks 38

Higher Speed Services for LAN Traffic 38

New Devices for Carrier and Internet Service Provider Networks 39

2 Telephone Systems, Peripherals and Cabling 45

Telephone Systems—PBXs, Centrex and Key Systems 47

What Is a PBX? 47

PBX Trunks 48

Demarcation—The Location Where Telcos Wire Trunks 48

PBX Telephones 49

Centrex—Telephone Company Supplied Service 50

Key Systems 53

Wireless PBX and Key System Telephones—On-Site Mobility 53

Direct-Inward Dialing—Bypassing the Operator for Incoming Calls 57

Convergence and Telephone Systems 58

Add-on Peripherals for Key Systems, PBXs and Centrex Systems 63

Call Accounting—Tracking Calls and Usage 64

ACDs—Specialized Equipment to Handle Large Volumes of Calls 72

Network-Based ACD Functions 73

LAN/PBX/ACD Connectivity to Enhance Productivity 74

Customer Relationship Management(CRM) for Call Centers 74

Integrated Voice Response Units—Using the Telephone as a Computer Terminal 76

Computer Telephony Integration(CTI)—Routing Callers More Intelligently 79

Media: Wireless, Fiber and Unshielded Twisted Pair Copper 80

Wireless LANs 81

Electrical Properties of Copper Cabling 83

Fiber Optic Cabling—High Capacity and High Costs 84

Part 2 Industry Overview 93

3 The Bell System and Regulatory Affairs 93

The Bell System Prior to and after 1984 95

Divestiture of the Bell System from AT&T in 1984 95

Regional Bell Operating Companies(RBOCs) after 1996 98

Transporting Calls Between Carriers 101

Local Competition Prior to the Telecommunications Act of 1996 103

Uneven Competition for Local Telephone Service Throughout the U.S. 103

Competitive Access Providers(CAPs) to Competitive Local Exchange Carriers(CLECs) 103

The Evolving View of the Feasibility of Local Competition 107

Factors Leading to Passage of the Telecommunications Act of 1996 108

Regional Bell Companies Desire to Expand Their Offerings 108

Interexchange Carriers ,Utility and Cable TV Companies Desires to Enter New Markets 108

Demand for High-Speed Telecommunications Services 109

Technological Capabilities to Provide High-Speed Services at Low Costs 109

The Viability of Wireless Services for Local Exchange Service 109

The Desire for a Uniform National Policy on Local Competition 110

The Telecommunications Act of 1996 110

Major Features of the Act 111

Post Telecommunications Act of 1996 Developments 117

FCC Rulings, Legal Challenges and Progress Toward Deregulation 117

Permission for RBOCs to Sell In-Region Long Distance 118

Unbundled Network Elements(UNEs)—Competitors Leasing Parts of RBOCs Networks 120

Fines Levied on Incumbents for Failure to Provide Timely Access to Competitors 121

Reciprocal Payments 121

Local Access Fees—A Shift in Balance Between Local and Long Distance Costs 122

Local Number Portability 123

Creating an Equal Playing Field and Conserving Numbers 123

Four Types of Telephone Number Portability 123

Impact of the Telecommunications Act of 1996 127

Appendix 129

4 Network Service Providers and Local Competition 135

Local Competition 137

Strategies for Entering the Local Calling Market—Resale, Wireless,Cable TV and Construction of Facilities 148

Carriers 155

Interexchange Carriers—IEXs 156

Bandwidth Trading:The Commoditization of Bandwidth 158

Merchants—Managing Risk for Carriers 159

Exchanges—A Place to Make Trades 160

Master Trading Agreements—Shortening the Transaction Cycle 161

Local Service Providers 161

AT&T 161

Competitive Local Exchange Carriers(Integrated Communications Providers) 163

Resellers and Switchless Resellers 167

Building Local Exchange Carriers(BLECs) 169

Agents 170

Summary 173

5 The Public Network 175

Switched Services—Local and Long Distance Calling 177

Attributes of Real-Time Switching Services 178

DTMF: Access to Voice Mail and Computers 183

Store-and-Forward Switching—Nonsimultaneous Sending and Receiving 184

Dedicated Services 184

Overview of Dedicated Services 185

Network Topologies—The View from the Top 188

Declining Sales of Private Lines 192

Virtual Private Networks—Connectivity for Remote Access,Intranets and Extranets 193

VPNs(Virtual Private Networks) for Electronic Commerce 194

VPNs for Intranet Service 194

Virtual Private Networks(VPNs) for Remote Access 195

Security on Virtual Private Networks 196

The Last Mile or Access Networks 197

End and Tandem Central Offices 199

Digital Loop Carrier Systems—Fiber Optics and Copper Cabling in the Last Mile 201

Carrier Hotels—Interconnecting Carriers and Providing Secure Space for Equipment 202

Optical Networking 203

Passive Optical Networks 204

Optical Add and Drop Multiplexers(OADM) 207

Optical Cross Connects(OXC)—Optical Switches 208

Network Intelligence and Signaling 212

Overview of Signaling 213

Background 215

Common Channel Signaling, Efficiency and Redundancy 218

Signaling System 7—The Glue for Links Between Carriers 218

SS7 Components 220

Convergence—Technical Advances Leading to Improvements in IP Networks 221

Improvements in Routers 222

Digital Signal Processors(DSPs) 223

Voice Compression 224

Higher Capacity Networks—Optical Technologies 224

Softswitches—Programmable Switches 225

The Quality of Service Issue for Voice over IP 227

SS7 in Packet Networks 228

Examples of Converged Networks 229

Free Calls or Low Priced Calls over the Internet 231

H.323—A Way to Make Telephone Calls over IP 232

Prepaid Calls over the Internet 232

Document Sharing and Click to Talk 233

Document Sharing 233

Summary 235

Part 3 Advanced Technologies,The Internet and Wireless 239

6 Specialized Network Services 239

T-1—24 Voice or Data Paths over One Telephone Circuit 243

Channel Banks—Connecting T-1 to Analog PBXs and Central Offices 244

DS-O and DS-1—64,000 or 56,000 vs. 1,544,000 bps 244

Media Used for T-1 Signals 245

European vs. American and Japanese T-1—24 vs. 30 Channels 246

A Sampling of T-1 Configurations Using T-1 for Combining Voice, Fax,Video and Data 247

Fractional T-1—When 24 Paths Are Not Required 248

T-3—The Capacity of 28 T-1 Lines, 672 Channels 249

An Explanation of Time Division Multiplexing and Its Limitations 249

ISDN—Integrated Services Digital Network 250

Basic Rate Interface ISDN—Two Channels at 64,000 Bit per Second 253

Primary Rate Interface ISDN—24 Channels 254

Digital Subscriber Line Technology 257

Competitive Iocal exchange carriers(CLECs) and DSL 261

Incumbent Telephone Company DSL Offerings 262

DSLAMs—Digital Subscriber Line Access Multiplexers 262

Obstacles to Digital Subscriber Line Availability—Cost, Ease of Implementation and Availability 263

DSL Lite—Lower Cost Service 266

DSL—A Technical Explanation 266

Frame Relay—A Shared Wide Area Network Service 267

Connections to Frame Relay—Frame Relay Access Devices and Access Line Speeds 269

Frame Relay for Transmitting Voice 270

Frame Relay Pricing—Ports, Circuits and Committed Information Rate 270

Potential Congestion on Frame Relay 271

Interfacing Between Carriers Frame Relay Networks 271

Gigabit Ethernet—Ethernet over Fiber in Metropolitan Areas 271

Gigabit Ethernet Providers—OLECs 272

Gigabit Ethernet Through Partners 273

Gigabit Ethernet Availability 273

The Advantages of Using Ethernet 273

Speed Options—Bandwidth on Demand 274

Gigabit Ethernet Features at Lower Prices 275

A Sample Metropolitan Area Gigabit Ethernet Configuration 275

ATM—Asynchronous Transfer Mode 276

Fixed-Sized Cells—Less Processing 278

Switching in Hardware—Less Address Lookup 278

Asynchronous Switching—Improving Network Utilization 278

Bursting—Selling More Than the Total Capacity 279

Scalability—The Ability to Use ATM for High-and Low-Speed Applications and IP Traffic 279

Elements of an ATM Network 280

SONET—Synchronous Optical Network 283

Synchronous Digital Hierarchy(SDH) and SONET 284

SONET Functions—The Four Layers 285

SONET Rings—For Greater Reliability 286

Telephone Company SONET Offerings 287

SONET Connections to Wave Division Multiplexers 288

Meshed Optical Technology—Lower Costs, More Suitable for Data than SONET 289

7 Analog, Cable TV and Digital Modems and Set-Top Boxes 291

Transferring Data from Computers to Telephone Lines 292

DCE—Connections to Telephone Lines 294

Modems—Analog Telephone Lines for Transmitting Data from Digital Devices 295

Fax Modems 296

56-Kbps Modems to Achieve Higher Speeds 296

PCMCIA Modems—Smaller Is Better 299

NTIS—CONNECTING DEVICES TO AN ISDN LINE 299

CSU/DSUs—Connecting Devices to a Digital Line 300

Cable Modems—Using Cable TV Facilities for Data Communications 301

Reverse Channels for Two-Way Data Communications 302

Cable Modems 302

Cable Modems for Business and for Remote Access 305

Set-Top Boxes 307

Interoperable Set-Top Boxes 308

Digital Cable TV 310

Appendix: Modem Standards 311

8 The Internet 315

The History of the Internet 317

Bulletin Board Systems(BBSs) 319

Who Runs the Internet? 319

Who Owns the Internet? 320

Peering—A Way to Exchange Data Between Networks 320

Content Delivery Networks(CDNs) and Caching—Solving the Problem of Bogged-Down Web Sites 321

Internet Services 322

The World Wide Web—Linking and Graphics 323

Hypertext Markup Language(HTML)—Formatting Web Pages 324

Home Pages 325

Hosting—Computers Connected to the Internet With Home Pages 327

Browsers—Moving from Web Site to Web Site 328

Email—Computers that Send, Store and Receive Messages 330

Email Attachments—To Aid Collaborative Projects 331

HTML Email as a Marketing Tool 332

Instant Messaging—Real-Time Text Chats 333

Internet Service Providers, Application Service Providers and Portals 335

Dialup and Dedicated Internet Access 336

Application Service Providers(ASPs) 338

Portals—Content as Well as Internet Access 338

Search Engines 342

Internet Addresses 346

Registries—Management of Entire Top-Level Domains 346

Registrars 347

Numeric IP Addresses 347

The Structure of Internet Addresses and Adding Capacity for More Addresses 347

New Generic Top-Level Domains(gTLDs) 348

Country Code Top-Level Domain Names(ccTLDs) 349

Electronic Commerce and Advertising on the Web 349

Advertising on the Web—A Source of Revenue 350

Online Commerce—What Is Profitable and Sells? 351

Privacy on the World Wide Web 354

Opt-out vs. Opt-in—Different Approaches to Protecting Privacy 356

Legal Issues 357

Post-Napster Music Industry Online Efforts 358

The Digital Millennium Copyright Act(DMCA)—Royalties for Radio over the Internet 359

Anti-pornography Laws and Freedom of Speech 359

Filtering Software—Policing Corporate Browsing and Email 361

Open Cable—Cable Companies as Both ISPs and Network Service Providers 361

ISP Service for Cable TV 361

Open Cable Service—Trialing Connections to Other IPS 362

Intranets and Extranets 365

Intranets—lmpact of Web Technology on Internal Operations 365

Extranets—Using Internet Technology With Customers, Partners and Vendors 366

Security on the World Wide Web—Establishing Trust 367

Public and Private Keys and Digital Certificates 368

Firewalls and Tunneling 368

Making the Internet a Trusted Place to Do Business 369

Conclusion 370

9 Wireless Services 371

Historical Background of Mobile and Cellular Services 376

Spectrum Allocation 377

Spectrum for Higher Speed 3G Services 378

Cellular Telephone Service—Technologies 379

Advanced Mobile Phone Services(AMPS) 379

Digital-Advanced Mobile Phone Service—D-AMPS 380

PCS—Personal Communications Services 381

GSM Service 382

Specialized Mobile Frequencies for Voice—Nextel 383

Cellular Vendors 384

Verizon Wireless 384

Cingular Wireless 384

AT&T Wireless 385

GSM Providers 385

Sprint PCS 386

The Structure of Cellular Networks 386

The Cellular Market 387

Efforts to Improve Service—Antenna Improvements 389

Health Concerns 390

Safety on the Road 391

Privacy and Advertising Intrusions on Cellular E911 394

Called Party Pays—An Impediment to Cellular Usage 395

Limited Mobility Wireless for Local Telephone Service 397

Wireless Number Portability—Keeping the Same Number When Changing Carriers 398

Limitations of Circuit-Switched Cellular for Data Communications 398

CDPD—Cellular Digital Packet Data, IP Wireless 398

The Transition from Second to Third Generation Cellular Networks 399

The Transition to W-CDMA-GPRS—Data Carried as Packets in 2.5G Networks 401

EDGE-Enhanced Data Rates for GSM Evolution 402

Upgrades to W-CDMA from GSM—Costly 402

The Transition to cdma2000—1xRTT(First Generation cdma2000) and HDR (High Data Rate) 403

A Comparison Between W-CDMA and cdma2000 404

Handsets for 3G and 2.5G Services 405

All-Packet Cellular Networks for Voice and Data 406

4G—Futures 406

Mobile Internet Access, Messaging Services and Bluetooth 406

Mobile Commerce 407

Short Messaging Service(SMS) 407

Bluetooth 408

The Wireless Application Protocol(WAP) 408

i-mode Service Worldwide 409

Specialized Mobile Radio—Originally Voice, Later Data 409

Private Networks over Mobile Radio Frequencies 410

Specialized Mobile Radio—Packetized Data Networks for Two-Way Email and Field Services 410

Paging Services 411

Paging vs. Wireless Telephone Service 412

Two-Way Paging Using Narrowband PCS 412

Satellites 413

VSAT Service—Small Satellite Dishes 414

Vendors of LEOs 416

Time Division Multiple Access, GSM and Code Division Multiple Access Air Interfaces 416

Code Division Multiple Access 418

Time Division Multiple Access and GSM 418

10 Globalization 419

The Impetus to Deregulate 421

Steps in Deregulation 421

Challenges 422

Trends in Global Markets 422

Latin America 424

Brazil 424

Mexico 429

Argentina 430

Impact of Poverty 433

Asia 437

China 437

Japan 442

The Internet 449

Cellular Service 450

Europe 453

The European Union 453

Cellular Service 455

Germany 457

The United Kingdom 460

France 462

Africa and the Middle East—Emerging Markets 471

Africa 472

The Middle East 472

Conclusion 473

Glossary 475

Bibliography 487

Index 489