Transcript Dodd_lecture_09

Wi-Fi, Wireless Broadband, Sensor
& Personal Area Networks
• 802.11
– Standards
– Applications
• Broadband Wireless Access
– WiMAX
– Adapting 3G for WBA: UMTS TDD
• Personal Area Networks: Bluetooth, RFID, UWB
• Sensor Networks - Zigbee
• Comparisons of Technologies & Applications
1
What is Wi-Fi?
• A wireless Ethernet standard
– Wi-Fi - (wireless fidelity) IEEE 802.11b, 802.11a & 802.11g
• Why standards matter
• The downside of standards
2
802.11 Standards
Standard
Top Speed
Achievable
Speed
802.11b
11 megabits
per second
5 megabits per
second
3
2.4 gigahertz
802.11a
54 megabits
per second
32 megabits
per second
12
5 gigahertz
802.11g
54 megabits
per second
14.4 megabits
per second
3
2.4 gigahertz
• 802.11n
• Range
• Capacity
• Data Rate
• Why these matter
No. of
Channe ls
Frequency
Band
3
Portability in Enterprises
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Laptops & handheld computers
Cabling
Need for computers in common areas
Reliance on GroupWare
Applications in vertical industries
4
802.11 Components
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•
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Access points
The user interface
Switches
Controllers
Each computer has a Wi-Fi
compatible card or chip & antenna
Modem to the
Internet
Wireless access
point
5
Workgroup
switches (which
are on individual
floors), access
points, and a core
switch in an
enterprise
network.
6
Wi-Fi in Hot Spots
•Speed
•Convenience
•Benefits to providers
7
A Clearinghouse for Single Sign on & Billing
Clearinghouse passes billing data to WISP
who bills user & pays clearing house a fee
8
A secure virtual private network (VPN) connection between
hotspots and enterprises using tunneling
9
WISPs & Aggregators
• WISPs
– Wayport
– T-Mobile
• Aggregators
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Boingo - billing “uber-aggregator”
GoRemote
iPass
Fiberlink
10
Mesh networks
11
Hot Spot Remote Access
Lost PDAs & laptops
 Eavesdropping
 Stolen data
Log in to WISP authenticated but data not
secured
12
Wi-Fi in Homes
• Why did residential customers use Wi-Fi earlier
than business & commercial customers?
• How will future residential applications differ
from initial applications?
• Is there a downside to Wi-Fi in homes?
13
Voice over IP on corporate 802.11 wireless networks
14
Security
• Security on wireless services compared to that of
wireline
• Software on access points or devices connected
to corporate networks
• Software on clients
15
What can go wrong?
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Unauthorized access
Snooping
Competitive information compromised
Rogue access points
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Security Tools
• WEP - Wired Equivalent Privacy
– Easy to “crack”
– Shared passwords
• WPA (Wi-Fi Protected Access) 802.11i subset
– 128 bit level of encryption - more scrambled
– “Keys” between user & access point changed more
frequently
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Implications for the CIO
Complexity Vs. ease of administration
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Compared to cellular
•13% of the cost of cellular data to provision*
•Stationary
•Speed
•Coverage
* Craig Mathias, the Farpoint Group
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What about WiMAX?
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802.16d - fixed
802.16e - mobile
Longer distances
MMDS - Multipoint Microwave Distribution
System
• Will these go the way of WinStar & Teligent?
20
WiMAX service with overlapping wireless coverage
between towers for redundancy
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WiMAX to Extend Wireline
Networks
ISP
Fiber
Provider’s Tower
Customers’
antennas
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Bluetooth
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Short distances
2.4 GHz
Standards
Version 1 vs. Version 2
Palm
Bluetooth wireless links
23
RFID service in hospitals to manage assets
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Ultra-wideband (UWB) low-power signals
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A ZigBee partial mesh network
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Summary
• Wi-Fi use in enterprises will increase when:___
• Hot spots compared to Cellular?
– Will wane as 3G grows
– Will outpace 3G
• Explain the differences & similarities between
fixed & mobile WiMAX
• Compare: bluetooth, RFID, Ultra-Wideband &
Zigbee
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