Deploying Wireless LANs / Edition 1

by Gilbert Held

Overview

Get mobility, speed, simplicity and lower cost of ownership from wireless LANs

Find out about the new standards, products, and broadband options that make wireless networks as fast and reliable as wired ones. You'll learn what they're good at, how to operate them, and what to buy in "Deploying Wireless LANs. Gil Held, the author of over 20 top-selling jargon-free tech guides, clearly and thoroughly explains how to plan and build wireless LANs capable of supporting mobile devices and applications. You don't even need a background in radio frequency engineering to understand:

How to make your 802.11 LAN fully compliant with 802.3 and Bluetooth Common access points and how they're changing LAN options Basic transmission troubleshooting techniques More!

Product Details

ISBN-13:	9780071380898
Publisher:	McGraw-Hill Companies, The
Publication date:	12/01/2001
Series:	McGraw-Hill Telecom
Pages:	352
Product dimensions:	7.36(w) x 9.20(h) x 0.96(d)

Table of Contents

	Preface	xv
	Acknowledgments	xvii
1	Introduction to Wireless LANs	1
	Overview	3
	Operation	3
	Network Configurations	4
	Roaming	6
	Extension Points	6
	Communications Methods	8
	Infrared	8
	Microwave	9
	Radio Frequency	9
	Benefits	11
	Utilization	11
	Hospital Use	12
	College Use	13
	Inventory Control	13
	Internet Access	14
	Training Centers	14
	Facilitating Networking	15
	Trade Show Use	15
	Benefits	16
	Constraints	17
	Book Preview	18
	Terminology and Technology	19
	Understanding Wireless LAN Modulation	19
	Understanding Wireless LAN Communications Systems	20
	Wireless LAN Hardware	20
	IEEE Wireless LAN Standards	21
	Installing a Wireless LAN	22
	The Home RF Standard	22
	The Future	22
2	Terminology and Technology	23
	Basic Communications Concepts	24
	Powers of Ten	25
	Frequency	26
	Wavelength	27
	The Frequency Spectrum	29
	Bandwidth	32
	Power Measurements	32
	Signal-to-Noise Ratio	37
	Transmission Rate Constraints	41
	Nyquist Relationship	42
	Radio Frequency Spectrum Allocation	45
	U.S. Spectrum Allocation	46
	Applications	49
	Other Transmission Impairments	50
	Basic Wireless LAN Components	51
	Path Loss	52
	Multipath Propagation	56
	Fading	57
	Enhancing Signal Reception	58
3	Understanding Wireless LAN Modulation	61
	Basic Modulation Methods	62
	Rationale	62
	Modulation Process	63
	Amplitude Modulation	64
	Frequency Modulation	65
	Phase Modulation	67
	Wireless LAN Modulation Methods	74
	DSSS Modulation	75
	Differential Binary Phase Shift Keying (DBPSK)	75
	Differential Quadrature Phase Shift Keying (DQPSK)	76
	Complementary Code Keying (CCK) QPSK	78
	Frequency Hopping Spread Spectrum (FHSS) Modulation	79
	Gaussian Frequency Shift Keying (GFSK)	79
	Orthogonal Frequency Division Multiplexing (OFDM) Modulation	80
	Quadrature Amplitude Modulation (QAM)	82
4	Wireless LAN Communications Systems	85
	Spread Spectrum Communications	86
	Development Rationale	86
	General Operation	87
	Spread-Spectrum Methods	88
	Direct Sequence Spread Spectrum (DSSS)	89
	Frequency Hopping Spread Spectrum	91
	Regulations	91
	Operational Parameters	93
	Packet Transmission Capability	94
	Hopping Modes	94
	Advantages of Use	95
	Direct Sequence Spread Spectrum	97
	Regulation	97
	Operation	98
	Using the Chipping Code	99
	Bandwidth Spreading	100
	Advantages of Use	101
	Disadvantages	102
	Coded Orthogonal Frequency Division Multiplexing	103
	Evolution	103
	Overview	105
	Operation	107
	Scrambling and Coding	108
	Advantages of Use	110
	Disadvantages	110
5	Wireless LAN Hardware	113
	Wireless Access Point	114
	Evolution	115
	Equipment Connection	115
	Using a Single Access Point	117
	Using Multiple Access Points	118
	Wireless LAN Network Cards	123
	Wireless Bridges	127
	Wireless Router/Gateway	136
6	IEEE Wireless LAN Standards	145
	The 802.11 Standards	146
	Overview	147
	Topology	148
	Portals	152
	The Physical Layer	152
	Modulation	154
	Frame Format	155
	Hopping Sequence	156
	Direct Sequence Spread Spectrum	157
	Overview	157
	Modulation	157
	Frequency Allocation	158
	Frame Format	158
	Infrared	159
	Modulation	160
	Frame Format	161
	The MAC Layer	162
	Basic Access Method	162
	Minimizing Collisions	163
	Interframe Spaces	166
	Collision Avoidance	167
	Frame Types	167
	RTS Frame	177
	CTS Frame	177
	ACK Frame	178
	Operation	179
	Joining an Existing Cell	179
	Authentication and Association	180
	Roaming	180
	The 802.11b Standard Extension	182
	Overview	183
	Operation	183
	Modulation	183
	The IEEE 802.11a Standard Extension	190
	Overview	190
	Modulation	191
	Frame Format	191
	Operation	193
7	Installing a Wireless LAN	195
	The SMC Networks Barricade Router	196
	Product Overview	196
	Features	197
	Site Location	198
	Wireless Positioning	198
	Connectivity Tradeoffs	199
	Using WINIPCFG	200
	Software Setup	202
	Verifying Computer--Router Connectivity	203
	Configuring the Router	204
	Configuration Options	205
	Wireless Settings	216
	Return to WINIPCFG	217
	The SMC Networks EZ Connect PC Card	218
	Driver Installation	219
	Configuration Utility	222
	Agere Systems Orinoco PC Card	227
	Installation	227
	The Client Manager	232
	Proof of the Pudding	234
8	The Home RF Standard	237
	Overview	238
	Versions	239
	Network Architecture	240
	Nodes	240
	System Requirements	241
	Technical Characteristics	241
	FHSS Use	241
	Power, Operating Rate, and Modulation	242
	Device Support	242
	Security	243
	Data Compression	244
	Home RF Operation	244
	The Physical Layer	245
	The MAC Layer	245
	Frame Duration and Types	246
	Frame Operations	247
9	The Future	251
	FCC Part 15 Ruling	252
	Overview	252
	ISM Band Use	253
	RF Interference	254
	The IEEE 802.11g Standard	255
	Backward Compatibility Issues	256
	Area of Coverage Consideration	257
	The IEEE 802.1x Standard	257
	Overview	258
	Operation	258
	Great Expectations	260
	AiroPeek, A Wireless Protocol Analyzer	260
	Overview	261
	Capturing Traffic	262
	Protocol Summary	264
	Packet Decoding	265
A	Hardware Manufacturers	267
	Locating Wireless Equipment on eBay	271
	Equipment Location	272
	The Bidding Process	277
B	Wireless LAN Economics	279
	Limited Client-Based Wireless LAN	280
	Access Point/Router-Based Wireless LAN	282
	Wired LAN Access	283
C	Practical Communications Security	285
	Glossary	289
	Index	303

Preface

Preface

A few years ago a popular TV commercial closed with the saying "the future is now." In the wonderful world of data communications the future has arrived in the form of wireless LANs. Once considered a niche technology that was expensive and limited with respect to its data transfer capability, wireless LANs are now reaching into every corner of our lives. If we travel we will more than likely encounter public areas in airports and hotel lobbies equipped with access points that enable us to surf the Web, check e-mail, and perform other activities using our laptop, notebook, or PDA equipped with a compatible wireless LAN adapter. If we check into a hotel, visit a sporting event, or register for a college course, we may also encounter persons using computers with a wireless LAN capability to access data from servers and main-frames by first connecting to an access point on a wired LAN behind the scenes.

The ability to transmit and receive data without having a wired connection frees us to locate computing equipment nearer to the area where it is useful. If you visit a modern big city hotel lobby you may encounter a reception area in the middle of an atrium. Behind the counter a hotel employee has a computer connected to the hotel LAN. However, instead of a wire connection that might require the lobby floor to be dug up, the connection occurs via a wireless LAN. Not only is the connection less expensive but the time required to place the computer into operation behind the reception area is probably a small fraction of the time that would be required to establish a wired connection.

In a university environment it becomes possible to set up regis- tration stations in a gymnasium very rapidly without running cables and having to temporarily tape them to the floor to allevi- ate the potential of students, administrators, and faculty tripping. Similarly, libraries can add and remove workstation connections to the Internet in tandem with special events they may hold.

In a home or apartment environment it is becoming common fo r a digital subscriber line (DSL)or cable modem to be installed to obtain a high-speed broadband access capability. One key nontechnical problem associated with the use of DSL and cable modems is the fact that your existing telephone and cable outlets may not be located in close proximity to your computer. Another related problem is the fact that many homes and apartments have multiple computers. Rather than rewire twisted pair or coaxial cable you can save time, avoid drilling holes in walls, and possibly save some money by installing a wireless LAN.

To day a wireless LAN provides us with the ability to communicate from locations that were previously difficult or impossible to support via wires. In addition, they provide a significant degree of flexibility and allow us to respond to changing requirements in a timely manner. Thus, when you think about networking, you should also think about wireless networking. When you do you will realize that the future is now!

As a professional author I value reader feedback. Although I have attempted to provide practical information throughout this book, I am human. To err is to be human, so if I omitted an area you feel I should have covered, spent too much time on a topic or assumed reader knowledge where a fuller explanation was warranted, please contact me. You can reach me either through my publisher, whose address is included on the jacket of this book or you can contact me via e-mail at [e-mail].

Gilbert Held
Macon, GA