Table Of ContentGoing Wi-Fi
A PRACTICAL GUIDE TO PLANNING AND
BUILDING AN 802.11 NETWORK
by Janice Reynolds
CRC Press
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c Taylor & Francis Group
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Table of Contents
Introduction 1 Chapter 4: The Regulators'
Role 52
Section 1: How Wi-Fi got What is Spectrum? 52
to Where it is Today 3 A History Lesson 54
Spectrum Allocation 58
Chapter 1: What is Wi-Fi 3
Spectrum Management 59
HotSpots are All the Rage 4 Technology to the Rescue 62
A Wireless Net 7
Open Spectrum, Anyone? 62
3G and Wi-Fi? 8
Conclusion 64
A Bit of Fiistory 9
Conclusion 12
Section II:
The Technology 67
Chapter 2: The Promise
ofWi-Fi 14 Chapter S: Modulation
Techniques 67
Freedom & Mobility 14
Installation Magic 16 An Introduction to Spread Spectrum 67
Impressive TOC and ROI 17 802.1 l's Modulation Techniques 72
The Business Community Benefits 18 CCK 73
Spawning Start-ups 23 OFDM 74
A Panacea for Developing Countries 24 Conclusion 76
Conclusion 29
Chapter 6: The Wi-Fi Standards
Spelled Out 77
Chapter 3: Fueling
the Wi-Fi Fire 31 The WLAN Family Tree 77
Synergy Helps to Hit a Home Run 35 An Alphabet Soup 82
Evolving Technology 37 802.11a 82
Applications 43 802.11b 90
Devices 48 802.llg 96
Conclusion 51 802.11c 103
/V
Coing WiFi
802.1 Id 103 Post-deployment Support Options 189
802.11e 103 Conclusion 189
802.1 If 104
Chapter 9: Bridging Buildings 191
802.1 lh 105
802.1 li 105 When to use Wireless Bridging 193
802.1 lj 114 Examples of Wireless Bridging 193
802.11k 114 The Disadvantages of Wireless
Bridging 194
802.111 116
Bridging Products 195
802.11m 116
Deployment 198
802.1 In 116
Case Studies 201
Conclusion 117
Conclusion 204
Section III:
Chapter 10: Contrasting
Practical Deployments 119 Deployments 205
Chapter 7: A WLAN Primer 119 Practical Deployments 205
Comparing 11a and 1 lb
a or b? 122
in an Office Environment 209
The Dual-band Option 132
The "b" / "g" Networking
802.11g 132 Environment 214
Wi-Fi and Ethernet 133 A Campus WLAN Design 221
A WLAN's Architecture 135 Conclusion 225
Security and Quality of Service 147
Network Management 148 Section IV: Building a
The Caveats 149 Wi-Fi Business 227
Conclusion 149
Chapter 11: The WISP
Industry 227
Chapter 8: A Practical WLAN
The Venue Layer—Operating
Deployment Plan 151
a HotSpot 229
The Task at Hand 152 HotSpot Operator Layer 232
The Assessment Process 152 The Aggregator Level 240
Deployment Team 155 Brands Layer 243
Technology Selection 157 The Lag in Investor Confidence 249
The Vendor Selection Process 159 Economic Fundamentals 250
Pre-Deployment Preparation 161 The Potential Market 253
Determining the Costs 170 Roaming Agreements 256
Deploying the WLAN 173 The Tech Side of Choosing
a HotSpot 260
VLANs 177
Business Plans and Legal Issues 261
End-user Training 182
The Value Chain 263
Four-Nines Reliability 182
Table of Contents V ______
A National Wi-Fi Network 264 Warehouses and Distribution
Centers 339
Case Studies 268
Retail 342
Conclusion 270
Healthcare 345
Chapter 12: Building Hospitality 358
a HotSpot 271 Field Service 362
HotSpot Kits 271 Manufacturing 365
Going it Alone 276 Education 372
Conclusion 279 Conclusion 383
Chapter 13: Wi-Fi and Section VI:
Cellular—A Dynamic Duo 280 Optimizing A WLAN 385
Can 3G and Wi-Fi Co-exist
Chapter 16: Providing Quality
in the Same Network? 280
ofService 385
Understanding Cellular 282
QoS Parameters 386
An Intelligent Pairing 292
IP Networks 387
Does a Dynamic Duo Make Good
Business Sense? 299 QoS for WLANs 389
Conclusion 300 End-to-End QoS 394
Applying QoS 405
Section V: Proprietary QoS Technology 406
Wi-Fi for the Enterprise 303 Multimedia in a Wi-Fi Network 408
Voice over Wi-Fi 409
Chapter 14: Wi-Fi in the
Corporate World 303 An Alternative to QoS 416
Conclusion 417
A Disruptive Technology 304
Take a Pragmatic Approach 305
Chapter 17: Dealing
Take it in Stages 305 with Security Issues 418
Assess the Situation 306
Security Basics 419
Which Wi-Fi Flavor? 309
Three Keys to Real Security 420
Hardware 313
Deploying a Secure WLAN 421
Pilot Project 313
Optional Security Measures 427
Return on Investment 324
Security Products 435
Enlarging the WLAN's Scope 327
Conclusion 442
Case Studies 327
Conclusion 332
Section VII:
The Hardware 443
Chapter 15: Vertical WLANs 333
Chapter 18: The Access Point 443
Take it in Stages 335
Vertical Hardware Considerations 335 Simple APs 444
Training Considerations 338 Smart APs 445
vi Going WiFi
The In-between "Fit" AP 446 Electrical 484
Comparing the Different Options 447 Conclusion 484
Intelligent Boxes 448
Dual Mode or Single Mode? 456 Section VIII:
AP Selection Criteria 457 Final Thoughts 485
Conclusion 459
Chapter 22: Wi-Fi's Future 485
Chapter 19: The Antenna 460 A Disorderly Infrastructure 486
Antenna Usage 460 How Fast Can It Go? 487
Antenna Types 462 Twenty Predictions 487
Antenna Positioning 464 Conclusion 490
Antenna Diversity 465
Chapter 23: Some Final
Antenna Selection Criteria 468
Musings 491
Conclusion 471
Wi-Fi's Time has Come 491
Chapter 20: Client Devices 472 Conclusion 492
The Selection Criteria 475
Appendix 1: The Open Systems
The Wireless Network Card 475 Interconnection (OSI) Model 493
Conclusion 478
Appendix II: Understanding
RF Power Values 498
Chapter 21: Cabling,
Connectors and Wiring 479 Appendix III: Regulatory Specifics
re Wi-Fi 502
Category 5 and 5e Cable 479
Glossary 505
Antenna Cable 480
Those Pesky Connectors 482 References 532
Lightning Arrestors 483 Index 533
1
Introduction
Imagine anywhere, anytime Internet access.
Imagine a network that allows employees to enjoy a professional career yet work at
home, without worrying about telephone jacks and cable outlets.
Imagine road warriors, armed with only a computing device (laptop or PDA), con
stantly on the move, quickly being able to sniff out wireless networks that provide high
speed Internet connections.
Imagine employees taking laptops to meetings, the cafeteria or even the warehouse—
always in touch, always available.
Imagine Web surfing for a company’s address and directions while sitting in traffic,
or uploading a big presentation to the office while commuting by bus or train. Or per
haps browsing the Web while sitting on a park bench, or reviewing the latest news while
you're waiting to pick up your kids from school. In other words, imagine being able to
go anywhere with the means to communicate always at your fingertips.
Have I whetted your interest?
All of these exciting possibilities and many more become real with the help of “Wi
Fi” (short for “wireless fidelity”) technology. The term Wi-Fi (which can be used inter
changeably with IEEE 802.11a, 802.11b, 802.llg, Wireless Local Area Network,
WirelessLAN, and WLAN) is the idiom commonly used to describe wireless networking
technology.
The author is among those believing that Wi-Fi represents the proverbial “next big
thing” in our culture. Creating a geographically extensive “Wireless Net” based on such
technology just might help launch the next big business cycle.
At present, media discussions of Wi-Fi emphasize how forward-thinking individu
als can set up and operate a network and gain high-speed Internet access without wires
or a monthly line fee. With perhaps the spotlight being shared by domestic wireless
Internet access with its tantalizing possibility: “Jetsonizing” one’s apartment, moun
tain retreat, lakeside cabin or oceanview condo with such far-out applications as remotely
controlling all domestic environmental settings (from lighting to climate control), telling
the oven to pre-heat in anticipation of popping in the roast that’s sitting in your refrig
erator, or programming the TiVo to start recording the big football game, now, since
you are stuck in traffic and won’t be home in time for the kickoff.
2 Going WiFi
But it’s not just individuals who will benefit from Wi-Fi. The opportunities Wi-Fi
offers to the business community are only limited by the stretch of the corporate imag
ination. Wi-Fi makes new business models possible—models that offer the potential of
a quick profit for a small investment. Wi-Fi and its anytime, anywhere Internet capabil
ities make it a standout as the next most promising area where entrepreneurial spirit and
technical creativity will burst wide open. Wi-Fi, like the Web, can flourish because its
technology runs atop the freely accessible communications standards of the Internet.
Wi-Fi has the potential to let anyone with a computing device connect to the Inter
net at high speed without the need for pesky cables. Instead of moving data through a
network using Ethernet cable, the most popular version of Wi-Fi (802.1 lb) transfers data
using a band of radio frequencies around 2.4 gigahertz (GHz). This is the same range
used by some cordless telephones. The data transfer rate of 801.11b is theoretically 11
Million bits per second (Mbps), but under normal conditions it’s usually between 4 Mbps
and 8 Mbps—far better than the 1.5 Mbps offered by a typical broadband connection.
Just as technical inventiveness and entrepreneurial daring opened the Web (and the
Internet) to pioneering information providers and hundreds of millions of users, so too
will Wi-Fi (at least, according to its proponents) make possible many cutting-edge inno
vations by making the Internet easier to connect to—at speeds comparable to today’s
fastest digital phone lines or cable modem hook-ups.
And guess what, it’s already happening! Wi-Fi networks are open to the public in
places like airport waiting lounges, cafés, coffee shops, bookstores, laundromats, brew
pubs, maybe even your next-door neighbor’s den. In fact, an estimated 15 million wire
less Net surfers in the U.S now use Wi-Fi hubs. Although the U.S. currently has the
largest number of Wi-Fi users, it is predicted that by 2006,100 million users worldwide
will be using some version of Wi-Fi.
As attractive as Wi-Fi is, however, IT managers must confront complex issues. For
example, viability with next generation technology—deploying a network today that can
be upgraded easily in the future. Then there’s the perennial issue of security. A firewall
costing thousands of dollars can be completely compromised by a single incorrectly
configured access point (a transmitting device that connects a wired local area network
to wireless computing devices, typically referred to as “clients”). WLANs could also fall
victim to their own success as multiple network standards, including Bluetooth, crowd
each other with interference. There are also Internet Protocol (IP) addressing issues, and
locating access points across subnets can make it difficult to roam from one location
to another without mobility middleware.
The good news is that solutions exist for most of these problems, and forthcoming
standards will address many of today’s limitations. The Wi-Fi technology available today
is good and it will only get better as time goes by, but to be successful in using it requires
careful navigation through an evolving landscape.
3
Section I: How Wi-Fi got to
Where it is Today
Chapter 1: What is Wi-Fi
“Wi-Fi” is a play on the old audio term “Hi-Fi” (high fidelity). The term also has been
trademarked by the Wi-Fi Alliance (formerly the Wireless Ethernet Compatibility Alliance).
Today, Wi-Fi is most commonly used to describe a wireless local area network based on
the IEEE 802.11 series of standards, which is a set of wireless technical specifications
issued by the Institute of Electrical and Electronic Engineers (IEEE). The IEEE is an
international professional organization for electrical and electronics engineers, with
formal links with the International Organization for Standardization (more commonly
known as the “ISO”).
The IEEE 802.11 standards specify an “over-the-air” interface consisting of radio fre
quency (RF) technology to transmit and receive data between a wireless client and a base
station or access point (an “infrastructure” configuration), as well as among two or more
wireless clients that happen to be within communications range of each other (an “ad hoc”
configuration).
The IEEE 802.11 standards resolve compatibility issues between manufacturers of
wireless networking equipment operating in specific frequency bands within the unli
censed spectra of 2.4 GHz and 5 GHz. (Unlicensed spectrum refers to airwaves that
haven’t been allocated to an exclusive user.) This wireless, flexible data communications
system can be implemented either as an extension to, or as an alternative for, a wired
local area network (LAN). As such, it is a wireless networking standard that’s accepted
worldwide and, consequently, has rapidly gained acceptance as an alternative to con
ventional wireline technologies.
The term “Wi-Fi” began life a few years ago as the IEEE 802.11 High Rate (HR) Stan
dard, which later became known as the IEEE 802.11b standard. Originally, “Wi-Fi” was
used only in place of the 802.1 lb standard (operating at 2.4 GHz and 11 Mbps), in the
same way that the term “Ethernet” is used in place of the wired LAN standard, IEEE
802.3. However, in October 2002, the Wi-Fi Alliance extended the “Wi-Fi” trademark to
include both 802.1 lb and its higher-bandwidth brother, 802.1 la (54 Mbps).
