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CWNA guide to wireless LANs 2nd ch01

CWNA Guide to Wireless
LANs, Second Edition
Chapter One
It’s a Wireless World


Objectives
• Describe how wireless technology is used in daily
activities
• Tell how wireless local area networks are used in
applications such as education, business, travel,
construction, and other areas
• Explain the advantages and disadvantages of
wireless technology

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A Day in the Life of a Wireless User:

Home
• Hotspots: Locations where wireless data services
are available
• Wireless local area network (WLAN): Essentially
identical to standard local area network (LAN)
– Except devices not connected by wires
– Can increase productivity

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A Day in the Life of a Wireless User:
Car
• Bluetooth wireless standard: Enables short
range wireless communication
– Used in many small devices

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A Day in the Life of a Wireless User:
Office
• Fixed broadband wireless: Wireless
transmissions between immobile devices
– Typically between office buildings
– Utilizes small, customized antennas

• Free space optics (FSO): Alternative to highspeed fiber optic transmissions

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A Day in the Life of a Wireless User:
Field


• Handheld devices used to connect to nearest cell
tower
– Cell tower connects to local telephone company
– Telephone company connects to appropriate
resources
• Such as e-mail servers

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A Day in the Life of a Wireless User:
On Site
• Radio frequency identification (RFID) tags:
– “Electronic barcodes”
– Used to identify items
– Can be read anywhere within range of transmitted
radio signal
• Depending on device

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A Look at Wireless Technologies
• Wireless technology woven throughout many
aspects of life
• Useful to get overview of some current
technologies in today’s wireless world

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Wireless Local Area Networks
(WLANs)
• Wi-Fi (Wireless Fidelity): Based on standard that
transmits at up to 11 Mbps
• Computers on WLAN must have wireless network
interface cards (wireless NIC or Wireless
adapter)
– Performs same basic functions as standard NIC,
plus more

• Access point (AP): Transfers signals between
wireless NICs
• Patch cable connects AP to wired LAN or Internet
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Wireless Local Area Networks
(continued)

Figure 1-3: Wireless LAN

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Wireless Local Area Networks
(continued)

Figure 1-4: Home wireless LAN

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Bluetooth
• Low-power wireless data and voice transmission
technology
• Bluetooth devices communicate via radio modules
– Link manager: Software that helps identify other
Bluetooth devices, creates links between devices,
and sends and receives data

• Transmit data at up to 1 Mbps over 10 meters
• Bluetooth devices within range of each other
automatically connect
– Master and slave
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Bluetooth (continued)
• Piconet: Bluetooth network containing a master
and at least one slave

Figure 1-5: Bluetooth device

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Telecommunications Links
• Integrated Services Digital Networks (ISDN):
Transmits at 256 Kbps
• T-1 lines: Transmit at 1.544 Mbps
• Cable modems: Use television cable connection
• Digital subscriber lines (DSL): Use telephone
lines
• WiMax: Signal transmitted between antennas
– Up to 75 Mbps and over up to 35 miles
– Fixed Broadband
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Telecommunications Links (continued)
• FSO: Transmit at speeds up to 1.25 Gbps over up
to 4 miles
– Line-of-site transmission

Figure 1-6: Free space optics transceiver

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Telecommunications Links (continued)

Figure 1-7: Wireless office technologies

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Cellular Telephony
• Global Systems for Mobile (GSM)
communications technology: Coverage includes
most of US and parts of Europe and Japan
– Transmission speeds up to 9.6 Kbps
– Information transmitted based on Wireless
Application Protocol (WAP)
• Standard way to transmit, format, and display data for
devices like cell phones and handheld devices

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Cellular Telephony (continued)

Figure 1-8: Browsing the World Wide Web

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Cellular Telephony (continued)
• WAP cell phone runs a microbrowser that uses
Wireless Markup Language (WML) instead of
HTML
• WAP gateway or proxy: Translates between WML
and HTML

Figure 1-9: WAP communications

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Radio Frequency Identification (RFID)
• Like an electronic barcode:
– Can contain larger amounts of updatable information
– Information transmitted via radio waves
– Range typically about 1 foot at 5 Mbps

Figure 1-10: RFID tag

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Wireless Technology Categories

Table 1-1: Typical wireless technologies

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Wireless LAN Applications: Education
• Educational institutions some of first adopters of
WLANs
– Dramatic advantages in teaching and learning

• Wireless LAN connections offer students important
degree of freedom
• WLAN technology translates into cost savings for
colleges
– Reduces need for wiring and infrastructure
– Fewer computer labs necessary

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Wireless LAN Applications: Education
(continued)

Figure 1-11: Campus access point locations

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Wireless LAN Applications: Business
• Wireless LAN technologies have significantly
changed how business conducted
– Meetings not confined to conference rooms
– Easier to connect to network resources and Internet
– Can create office in space where traditional
infrastructure does not exist

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Wireless LAN Applications: Travel
• Travel industry perhaps adopted wireless
technologies more than any other industry
– Many airport terminals provide wireless hotspots
– Several large airlines providing wireless capabilities
to passengers during flights
– Some airlines use WLAN technology to communicate
with aircraft on ground
– Some airlines use WLAN technology to facilitate
maintenance tasks
– Some airlines use new wireless data service to send
and receive messages

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