Designing and Deploying 802.11n Wireless Networks

• Copyright 2010
• Edition: 1st

• eBook
• ISBN-10: 1-58714-089-6
• ISBN-13: 978-1-58714-089-1

Gain a practical understanding of the underlying concepts of the 802.11n standard and the methodologies for completing a successful wireless network installation

Practical, start-to-finish guidance for successful deployment of 802.11n wireless LANs

With the ratification of the 802.11n wireless LAN standard, thousands of companies are moving rapidly toward implementation. However, 802.11n is very different from legacy 802.11a, 802.11b, and 802.11g wireless standards, and successful deployment requires new knowledge and techniques. In this book, leading wireless expert Jim Geier systematically presents all the information and guidance that network architects, engineers, administrators, and managers need to maximize the performance and business value of new 802.11n networks.

Drawing on extensive experience with real-world 802.11n deployments, Geier guides you through the entire project lifecycle: planning, design, installation, testing, monitoring, and support. Each phase of wireless LAN deployment is organized into clearly defined steps, and multiple case studies and hands-on exercises show how to apply each technique.

You’ll find practical guidance for deploying in enterprises without existing wireless infrastructure, as well as migrating from legacy 802.11a, 802.11b, or 802.11g networks. For convenient reference, Geier also provides an extensive, up-to-date wireless networking glossary.

Jim Geier founded Wireless-Nets, Ltd., and serves as its principal consultant. His 25 years of experience include analysis, design, implementation, installation, and support of wireless network-based solutions for cities, enterprises, airports, manufacturers, warehouses, hospitals, and other facilities worldwide. He is author of more than a dozen books, including Wireless Networks - First Step and Deploying Voice over Wireless LANs (Cisco Press) and Implementing 802.1X Security Solutions. He has been active with the IEEE 802.11 Working Group developing international wireless LAN standards, and chaired the IEEE International Conference on Wireless LAN Implementation.

• Understanding 802.11n MAC, physical layer, and related standards
• Designing 802.11n wireless networks for diverse scenarios: considering architecture, range, performance, roaming, and RF issues
• Migrating from 802.11a, 802.11b, and 802.11g wireless networks
• Choosing the right tools and equipment, and using them effectively
• Planning effectively: scoping projects; creating work breakdown structures; organizing teams, schedules, and budgets; defining requirements, and more
• Securing WLANs via encryption, authentication, rogue access point detection, RF shielding, and polices
• Performing site surveys and identifying optimum access point locations
• Installing and configuring wireless LANs: planning, staging, deployment, documentation, and more
• Systematic testing to improve signal coverage, performance, and security
• Managing wireless LANs: help desk support, network monitoring, maintenance, engineering, configuration management, security, tools, and more
• Troubleshooting 802.11n networks: identifying issues with connectivity, performance, and more

Table of Contents

                Introduction xxv

Part I Fundamental Concepts

Chapter 1 Introduction to Wireless LANs 1

Wireless LAN Markets and Applications 1

                Retail 2

                Warehousing 3

                Healthcare 4

                Hospitality 9

                Voice over WLAN 9

                Video Surveillance 11

                Home and Small Office 12

                General Enterprise Systems 13

                Location-Aware Wireless Applications 13

Benefits of Wireless Networks 15

                Mobility 15

                Installation in Difficult-to-Wire Areas 16

                Increased Reliability 17

                Reduced Installation Time 17

                Long-Term Cost Savings 17

                Productivity Gain Is the Answer 18

Wireless Network Technologies 19

                IEEE 802.11 (Wi-Fi) 20

                Initial 802.11 20

                802.11a 21

                802.11b 21

                802.11g 22

                802.11n 23

                Comparison of 802.11 Standards 24

                Wi-Fi Certification 24

Other Wireless Network Technologies 26

                IEEE 802.16 (WiMAX) 26

                IEEE 802.15 (Bluetooth) 30

                IEEE 802.15.4 (ZigBee) 32

                Certified Wireless USB 33

Wireless LANs: A Historical Perspective 34

                The Early Days 34

                Initial 802.11 Standardization 35

                802.11n Standardization 36

Chapter 2 Radio Wave Fundamentals 39

Radio Wave Attributes 39

                Amplitude 40

                Frequency 40

                Phase 41

RF System Components 41

                RF Transceiver 41

                RF Modulation 43

                Amplitude Shift-Keying 43

                Frequency Shift-Keying 44

                Phase Shift-Keying 45

                Quadrature Amplitude Modulation 45

                Spread Spectrum 45

                Orthogonal Frequency-Division Multiplexing 48

RF Signal Propagation 48

                Attenuation 48

                Free Space Loss 49

                Physical Obstacles 50

                Multipath Propagation 51

                Noise and Signal-to-Noise Ratio 51

RF Mathematics 53

                Converting Units 53

Chapter 3 Wireless LAN Types and Components 55

Types of Wireless LANs 55

                Ad Hoc Wireless LANs 55

                Infrastructure Wireless LANs 57

                Mesh Wireless Networks 59

Wireless LAN Components 62

                Client Devices 62

                Client Radio 63

                Industry Standard Architecture 65

                Peripheral Component Interconnect 66

                Mini-PCI 66

                PC Card 66

                ExpressCard 67

                CompactFlash 67

                Universal Serial Bus 67

                Access Points 68

                Autonomous Access Points 68

                Controller-Based Access Points 69

                Wi-Fi Routers 69

                Mesh Nodes 72

                Antennas 72

                RF Amplifiers 74

                Repeaters 75

                Bridges 75

Network Infrastructure Components 77

                Network Distribution Systems 77

                Switches 77

                Optical Fiber 79

                Power over Ethernet 79

                Application Connectivity Software 82

                Terminal Emulation 82

                Browser-Based Approaches 83

                Direct Database Interfaces 84

                Wireless Middleware 84

Chapter 4 Wireless LAN Implications 87

Security Vulnerabilities 87

                Passive Monitoring 88

                Unauthorized Access 91

                Denial of Service 95

Radio Signal Interference 97

                Microwave Oven Interference 99

                Cordless Phone Interference 101

                Bluetooth Interference 103

                Neighboring Wireless LAN Interference 105

Impacts of Multipath Propagation 108

                Roaming Issues 109

                Battery Limitations 110

                Interoperability Problems 111

                Installation Issues 112

Part II The 802.11 Standard

Chapter 5 Introduction to IEEE 802.11 and Related Standards 115

The Importance of Standards 115

                Types of Standards 115

                Institute for Electrical and Electronic Engineers 117

                Benefits of the 802.11 Standard 117

                Appliance Interoperability 118

                Fast Product Development 119

                Stable Future Migration 119

                Price Reductions 119

                Avoiding Silos 119

The IEEE 802 LAN Standards Family 120

                802.11 MAC Sublayer 121

                802.11 Physical Layer 123

                IEEE 802.2 123

                Unacknowledged Connectionless Service 124

                Connection-Oriented Service 125

                Continuous ARQ 126

                Stop-and-Wait ARQ 127

                Acknowledged Connectionless Service 128

IEEE 802.11 Features 129

                Station Services 130

                Authentication 130

                Deauthentication 131

                Privacy 131

                Distribution System Services 131

                Association 131

                Disassociation 131

                Distribution 131

                Integration 132

                Reassociation 132

                Station States and Corresponding Frame Types 132

Chapter 6 IEEE 802.11 Medium Access Control (MAC) Layer 135

Primary 802.11 MAC Layer Functions 135

                Data Delivery 136

                Medium Access 137

                Distributed Coordination Function 138

                Hybrid Coordination Function 139

                Error Recovery 140

                Data Frame Acknowledgments 140

                Dynamic Rate Switching 141

                Data Frame Aggregation 142

                MSDU Aggregation 143

                MPDU Aggregation 143

                Data Frame Fragmentation 143

                Encryption 145

                Wired Equivalent Privacy 145

                Temporal Key Integrity Protocol 146

                Advanced Encryption Standard 146

                Multicasting 147

Connectivity 148

                Scanning for Networks 149

                Authentication 151

                Open System Authentication 151

                Shared Key Authentication 152

                IEEE 802.1X Port-Based Authentication 153

                Association 154

                Reassociation 155

Timing and Synchronization 156

                Short IFS 156

                PCF IFS 157

                DCF IFS 157

                Extended IFS 157

RTS/CTS 158

                Power Management 159

802.11 MAC Frame Structures 160

                Protocol Version Field 160

                Type Field 161

                Subtype Field 161

                To DS Field 161

                From DS Field 161

                More Frag Field 161

                Retry Field 163

                Power Management Field 163

                More Data Field 164

                Protected Frame Field 164

                Order Field 164

                Duration/ID Field 164

                Address 1, 2, 3, and 4 Fields 164

                Sequence Control Field 165

                QoS Control Field 166

                HT Control Field 166

                Frame Body Field 166

                Frame Check Sequence Field 166

MAC Frame Types 166

                Management Frames 167

                Association Request Frame 167

                Association Response Frame 167

                Reassociation Request Frame 167

                Reassociation Response Frame 167

                Probe Request Frame 168

                Probe Response Frame 168

                Beacon Frame 168

                ATIM Frame 170

                Disassociation Frame 170

                Authentication Frame 170

                Deauthentication Frame 170

                Action Frame 170

                Action No ACK Frame 171

                Management Frame Body Contents 171

                Control Frames 172

                Control Wrapper Frame 172

                Block ACK Request Frame 172

                Block ACK Frame 172

                Power-Save Poll Frame 173

                Request-to-Send Frame 173

                Clear-to-Send Frame 173

                Acknowledgment Frame 173

                Contention-Free End Frame 173

                CF End + CF ACK Frame 173

                Data Frames 174

Interoperability 174

Chapter 7 IEEE 802.11 Physical Layers 177

802.11 Physical Layer Architecture 177

                PLCP Sublayer 177

                PMD Sublayer 178

802.11 Physical Layer Functions 179

                Carrier-Sense Function 179

                Transmit Function 179

                Receive Function 180

Legacy 802.11 Physical Layers 180

                Frequency-Hopping Spread-Spectrum PHY 180

                Direct-Sequence Spread-Spectrum PHY 182

                Infrared PHY 185

                Orthogonal Frequency Division Multiplexing PHY (802.11a) 185

                High-Rate Direct-Sequence Spread-Spectrum PHY (802.11b) 188

                Extended-Rate PHY (802.11g) 190

HT-OFDM (802.11n) 190

                MIMO Concepts 190

                Transmit Beamforming 190

                Spatial Multiplexing 191

                Channel Bonding 193

                802.11n Modulation 194

Interoperability 198

Part III Wireless Network Design

Chapter 8 Planning a Wireless LAN Deployment 201

Project Management Principles 202

Wireless LAN Deployment Planning Steps 204

Step 1: Defining the Project Scope 204

                Project Charter 204

                Assumptions 204

                Constraints 205

Step 2: Developing the Work Breakdown Structure 206

                Requirements Definition Phase 206

                Design Phase 207

                Implementation Phase 209

                Operations and Maintenance Phase 211

Step 3: Identifying Staffing 214

Step 4: Creating a Schedule 217

Step 5: Developing a Budget 218

                Preliminary Requirements and Design 218

                Hardware and Software Costs 219

                Deployment Services Costs 221

                Ongoing Operations and Maintenance Costs 223

Step 6: Evaluating Risks 225

Step 7: Analyzing Feasibility 227

                Costs 228

                Benefits 228

                Impacts on Users 229

                Impacts on Existing Systems 229

                Making the Decision to Proceed 229

Executing the Project 232

                The Kick-Off Meeting 232

                Periodic Activities 233

Evaluating the Outcome of the Project 233

Chapter 9 Defining Requirements for a Wireless LAN 237

Requirements Attributes 238

Requirements Definition Steps 238

Step 1: Gathering Information 239

                Interviewing Users 239

                Interviewing IT Staff 240

                Reviewing the Existing Infrastructure and Systems 240

Step 2: Analyzing Requirements 241

                Application Requirements 241

                Client Device Requirements 243

                Signal Coverage Requirements 244

                Utilization Requirements 246

                Mobility Requirements 248

                Continuous Movement 248

                Portable Access 249

                Stationary Access 249

                Security Requirements 250

                Sensitivity of Information and Systems 250

                Organization Security Policies 251

                Network Access Privileges 251

                Existing Security Mechanisms 252

                Scalability Requirements 253

                Existing Network Infrastructure Requirements 254

                Integration Requirements 255

                Environmental Requirements 256

                Building Construction and Obstacles 256

                Floor Plans 256

                Temperature and Humidity 256

                Durability 257

                Aesthetic Requirements 258

Step 3: Documenting Requirements 259

Step 4: Obtaining Requirements Approval 260

Chapter 10 System Architecture Considerations 263

Architectural Considerations 264

Wireless Access Networks 264

                Autonomous Access Point Architecture 265

                Controller-Based Access Point Architecture 267

                Mesh Network Architecture 269

                Ad Hoc Architecture 270

                2.4 GHz Versus 5 GHz 272

                Geographical Location Considerations 272

                Performance Considerations 272

                Existing Client Device Considerations 273

                Facility Size Considerations 273

                Radio Signal Interference Considerations 273

                Hybrid Frequency Band Considerations 274

                Common Infrastructure Considerations 274

                Migration Considerations 276

                Redundancy Considerations 277

                Controller Redundancy 277

                Access Point Redundancy 279

Distribution Systems 282

                Switch Considerations 282

                PoE Considerations 282

Voice over WLAN Systems 284

                Single-Site Architecture 284

                Multisite WAN with Centralized Call Processing 285

                Multisite WAN with Distributed Call Processing 287

Application Connectivity 289

                Terminal Emulation Considerations 289

                Browser-Based Connectivity Considerations 292

                Direct Database Considerations 293

                Wireless Middleware Considerations 294

Chapter 11 Range, Performance, and Roaming Considerations 299

Range Versus Performance 299

Range Considerations 300

                Signal Coverage Requirements 300

                Radio Frequency Bands 301

                Transmit Power Settings 302

                Transmission Channel Settings 303

                Data Rate Settings 304

                Antennas 306

                Amplifiers 307

                Repeaters 308

                Physical Obstacles 309

                Radio Signal Interference 309

Performance Considerations 311

                Throughput Versus Data Rate 312

                Radio Frequency Bands 313

                Transmit Power Settings 313

                Transmission Channel Settings 314

                Data Rate Settings 315

                Antennas 315

                Amplifiers 316

                Radio Signal Interference 316

                Channel Width Settings 316

                Signal Coverage 317

                Fragmentation Settings 317

                RTS/CTS Settings 318

                Bandwidth Control Mechanisms 319

                Microcell Deployment Strategies 319

Roaming Considerations 321

                Roaming Levels 322

                Access Point Roaming 322

                Subnet Roaming 323

                Wireless ISP Roaming 324

                Wireless IP Phone Roaming 324

                Mobility Settings 325

Chapter 12 Radio Frequency Considerations 327

Frequency Band Selection 327

                2.4-GHz Frequency Band 327

                5-GHz Frequency Band 328

Transmission Channel Settings 328

                Manual Channel Settings 328

                Single-Level Facilities 329

                Multilevel Facilities 330

                Adaptive Channel Settings 332

Difficult-to-Cover Areas 333

                Signal Coverage in Elevators 333

                Signal Coverage in Stairwells 336

                Signal Coverage in Parking Areas 336

Radio Signal Interference Reduction 337

Chapter 13 Security Considerations 339

Security Elements 339

Encryption 340

Authentication 342

                EAP Methods 342

                Authentication Servers 344

                Guest Access 345

Rogue Access Point Detection 346

RF Shielding 347

Wireless Security Polices 349

Part IV Wireless Network Installation and Testing

Chapter 14 Test Tools 353

Tool Considerations 353

Spectrum Analyzers 354

                Real-Time Fast Fourier Transform 354

                FFT Duty Cycle 356

                Swept Spectrogram 357

                Active Devices 357

                Recording Spectrum Data 358

Signal Coverage Testers 358

                Heat Maps 358

                Positioning 360

                Passive Versus Active Modes 361

                Simulation 361

                Free Signal Coverage Tester: NetStumbler 361

Wireless Protocol Analyzers 362

                Filtering Frames 363

                Recording Traces 363

                Free Protocol Analyzer: WireShark 364

Chapter 15 Performing a Wireless Site Survey 367

Wireless Site Survey Considerations 368

Reviewing Requirements 369

Selecting Site Survey Tools 370

Obtaining Floor Diagrams 371

Inspecting the Facility 372

Assessing the Existing Network Infrastructure 372

                Communications Rooms 372

                Switches and Power over Ethernet 373

                WAN 373

Identifying Potential Radio Signal Interference 373

Defining Signal Values for Acceptable Signal Coverage 376

                Minimum Received Signal Strength 376

                Minimum SNR 376

                Uplink Versus Downlink Signal Values 377

Identifying Optimum Access Point Antenna Installation Locations 379

                Propagation Testing 379

                Test Access Point Configuration 379

                Antenna Considerations 379

                Identifying Test Locations 380

                Measuring Test Signals 381

                Assessing Propagation Test Results 382

                Cell Overlap Considerations 383

                Annotate Access Point Antenna Installation Locations 384

Writing an RF Site Survey Report 385

Chapter 16 Installing and Configuring a Wireless LAN 387

Wireless LAN Installation Considerations 387

Planning the Installation 388

                Developing an Installation Plan 388

                Points of Contact 388

                Safety Tips 389

                Installation Procedures 389

                Required Facility Changes 390

                Tools 390

                Reference to Design Documentation 390

                Schedule 390

                Resources 391

                Budget 391

                Risks 391

                Coordinating the Installation 391

Staging the Components 392

Installing Ethernet Switches and Cabling 393

Installing Access Points 394

                Mounting Practices 394

                Antenna Alignment 395

                Configuration Setting Access 396

                Firmware 396

                Access Point Configuration Settings 396

                802.11n Enable 396

                SSID 396

                DTIM Interval 397

                Beacon Interval 397

                Radio Frequency Bands 398

                Transmit Power 398

                Transmission Channel 399

                Data Rates 399

                Antenna Diversity 399

                Channel Width 401

                Fragmentation Threshold 401

                RTS/CTS Threshold 402

Testing the Installation 402

Documenting the Installation 403

Chapter 17 Testing a Wireless LAN 405

Wireless LAN Testing Considerations 405

Signal Coverage Testing 406

                Wireless Site Survey Coverage Testing 406

                As-Installed Coverage Testing 407

                Consider Beacon Rates 407

Performance Testing 408

                Association Tests 408

                Registration Tests 409

                Network Connection Tests 409

                Authentication Tests 410

                Application Connection Tests 410

                Application Tests 410

                Load Tests 411

In-Motion Testing 412

Security Vulnerability Testing 413

                Security Settings Verification 413

                Penetration Testing 414

                Private-Side Testing 414

                Public-Side Testing 414

Acceptance/Verification Testing 415

Simulation Testing 416

Prototype Testing 417

Pilot Testing 418

Test Documentation 419

Part V Operational Support Considerations

Chapter 18 Managing a Wireless LAN 421

Operational Support Considerations 421

Help Desk 422

                Connection Problems 422

                Poor Signal Coverage 423

                Poor Performance 423

                System Status 423

                Additional Considerations 423

Network Monitoring 424

                Performance Monitoring 424

                Access Point Monitoring 424

                Configuration Monitoring 425

                Security Policy Management 425

                Installation Control Policies 425

                Monitoring Policies 425

                Periodic Testing Policies 426

Maintenance 426

                Inoperative Access Points 426

                Poor Performance 426

                Poor Signal Coverage 426

                Broken Hardware 427

                Firmware Updates 427

                Signal Coverage Verification 427

                Access Point Inspections 428

                Troubleshooting 428

                Sparing 428

Engineering 428

                Advanced Problem Resolution 429

                Coverage Expansion 429

                Capacity Increases 429

                Firmware Review 429

                Technology Upgrades 430

                Design Review 430

Configuration Management 430

                Change-Control Processes 430

                Security Management 431

                Review Existing Security Policies 432

                Review the System Architecture 432

                Review Management Tools and Procedures 432

                Interview Users 433

                Verify Configurations of Wireless Devices 433

                Investigate Physical Installations of Access Points 433

                Identify Rogue Access Points 433

                Perform Penetration Tests 434

                Analyze Security Gaps 434

                Recommend Improvements 434

Trouble Ticket Coordination 435

                Help Desk Group 435

                Desktop Support Group 436

                Network Support Group 436

Preparing for the Transfer to Operational Mode 436

Chapter 19 Troubleshooting a Wireless LAN 439

Troubleshooting Methodology 439

                Identify the Problem 439

                Identify the Underlying Cause of the Problem 440

                Fix the Problem 440

Connection Problems 440

                Insufficient Signal Coverage 441

                Radio Signal Interference 442

                Access Point Failure 442

                Incompatible Client Radio 442

                Faulty Firmware 443

                Incorrect Client Radio Configuration 443

Performance Problems 444

                Insufficient Signal Coverage 444

                Radio Signal Interference 444

                Faulty Firmware 445

                Nonoptimal Client Radio Configuration 445

                Nonoptimal Access Point Configuration 445

                Misaligned Antennas 446

                High Utilization 447

Chapter 20 Preparing Operational Support Staff 449

Support Staff Considerations 449

Availability of Existing Staff 450

Experience Requirements 450

Education and Training Requirements 451

                Vendor-Neutral Training 451

                Vendor-Specific Training 452

                College Education 452

Certifications 452

Staffing Sources 453

Glossary 455

9781587058899, TOC, 5/7/10

Submit Errata