Format of lecture
Introduction to Wireless
Wireless standards
Applications
Hardware devices
Performance issues
Security issues
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Wireless Technology
Wireless and mobile computing are the keywords
Very topical/exciting
This technology not yet mature
Promises that we can improvise our existing
networks without having to lay new wires - roving
staff will just have to insert a wireless card into
their device and join the network
Interesting to compare the what the Telco’s are
doing with 3G and how this rivals WiFi hotspots
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Wireless Technology
Wireless technology has to compete with
digital satellite
Cable
phone lines (HomePNA) 10Mbps
Power line (HomePlug) 14Mbps
Wireless broadband technology (WiMax)
gives wire-free transmission of two way
multimedia
Bandwidth is an issue here
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Wireless Technology
What is on the market/coming?
Communication cards to allow data from personal
digital assistants to be synchronised with desktop
PC’s
Cards to link laptops and PC’s with Global System
for Mobiles(GSM) based phones and local area
network devices
All the above enables firms to set up wireless
networks without having to use Ethernet cable
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Wireless Protocols
Wireless LAN
Bluetooth
WAP/GPRS/UMTS
SWAP - Shared Wireless Access Protocol
3G - third generation cellular standard
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Wireless versus Wired networks
Using Radio frequency (2.4GHz and 5GHz)
Easy to setup a small office or home office
(SOHO)
Mobility
Travel through wall
Easy for network reconstruction
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What is WiFi?
Wireless LAN IEEE 802.11x network
Promulgated by an association called WiFi
Alliance
WiFi Alliance certifies all wireless LAN
IEEE802.11x based products for
interoperability
All IEEE802.11x based products that passed
the WiFi Alliances are called WiFi
Wireless Fidelity
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WiFi Standards
IEEE 802.11a
An IEEE standard for a wireless network that
operates at 5 GHz with rates up to 54Mbps
IEEE 802.11b
An IEEE standard for a wireless network that
operates at 2.4 GHz with rates up to 11Mbps
IEEE 802.11g – referred to as 54g (but don’t
confuse that with the 54Mbps!)
An IEEE standard for a wireless network that
operates at 2.4 GHz with rates up to 54Mbps
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WiFi Standards
WPA (WiFi protected Access)
TKIP encryption and protects against unauthorized
network access through the use of a pre-shared
key (PSK)
WMM (WiFi MultiMedia)
packet prioritisation that meet IEEE 802.11e quality
of service standard.
Packets containing time-dependent data such as
audio or video to be sent ahead of data that can
safely wait a few microseconds
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WiFi Hardware
Access points (APs)
PCMCIA cards/ PC cards
USB adapters
PCI network cards
Wireless routers
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WiFi Applications
Retails
Warehouses
Healthcare
Education
http://www.wifinetnews.com/
News about wifi and also see if you can find out the
hotspot(s) around the Stoke-on-Trent area
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WiFi topology
Ad Hoc
Without use of Access Point
Peer-to-peer style communication
Recommended 3 or less users per channel
Infrastructure
Communication each other devices by the use of
Access Point
About 10-30 users per access point
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Ad Hoc vs Infrastructure
Ad Hoc can be setup instantly for temporary
solution
Scalability is limited to Ad Hoc
Coverage
Reliability
Efficiency
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Wireless LAN
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Security choices
Network security ensures the communications and
files are protected
How important of the security depend on how you
want to use the network.
Browsing internet and mp3 streaming may not need a
security
Internet shopping or purchasing will use SSL security
There are several way to protect your data
confidentiality while transmitting
In WLAN, you can change your SSID, WEP or WPA
or latest technology WPA2
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Wireless surfing
Common knowledge that some users use someone
else’s network connection to use the Internet
“piggybacking”
Hi-gain antenna example that I use
How do you know someone is using you?
If infrastructure – you don’t – would have to look at router logs
Ad-hoc – shows in connections window
How do they know you are not using them in return?
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WEP
Wired Equivalent Privacy
Encrypt data over the radio waves
Implemented in MAC layer – NIC encrypt the frame
before transmit
Using 64bits or 128bits encryption keys
Shared secret key
You need to provide 40 bits (10 digit Hex) or 104bits (26
digit Hex)
24 bits Initialisation Vector (IV) for generating key
sequence
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Limitation of WEP
Share, static keys
WEP only encrypt frame within wireless
station but not within wired network
Limited IV numbers and may increase
collision - IV repeats after sending 26GB.
Recovery attack - the data can be
manipulated after a few hours by tracking
repeating IV
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WPA and WPA v2
WiFi Protected Access
Different key for each user
48 bit IV – defeats recovery attack on WEP
Use Temporal Key Integrity Protocol (TKIP)
which dynamic change keys on transmission
More information on http://www.wifi.org
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Summary
Security is the main issues in wireless
communications
Still in the development to increase the
privacy
Next tutorial you will see wireless security in
action
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