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By MD MONIRUZZAMAN DEPT:-ECE 3RD YEAR WBUT ROLL NO: 09148003059
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PRESENTATION ON WI-FI TECHNOLOGY
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-:ACKNOWLEDGEMENT :-
My respected teacher:
Prof. Tarun Kumar Das
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-:CONTENTS:- # Introduction # Wi-Fi Technologies # Wi-Fi Architecture # Wi-Fi Network Elements # How a Wi-Fi Network Works # Wi-Fi Network Topologies # Wi-Fi Configurations # Applications of Wi-Fi # Wi-Fi Security # Conclusions # Reference # Bibliography
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Introduction# Wireless Technology is an
alternative to Wired Technology, which is commonly used, for connecting devices in wireless mode.
# Wi-Fi (Wireless Fidelity) is a generic term that refers to the IEEE 802.11 communications standard for Wireless Local Area Networks (WLANs).
# Wi-Fi Network connect computers to each other, to the internet and to the wired network.
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The Wi-Fi TechnologyWi-Fi Networks use Radio
Technologies to transmit & receive data at high speed:
# IEEE 802.11b(1999)# IEEE 802.11a(2001)# IEEE 802.11g(2003)
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802.11 Physical
Layer# There are three sub layers in physical layer: 1. Direct Sequence Spread Spectrum (DSSS)
2.Frequency Hoping Spread Spectrum (FHSS)
3.Diffused Infrared (DFIR) - Wide angle 6
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DSSS# Direct sequence signaling
technique divides the 2.4 GHz band into 11 22-MHz channels. Adjacent channels overlap one another partially, with three of the 11 being completely non-overlapping. Data is sent across one of these 22 MHz channels without hopping to other channels.
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IEEE 802.11 Data Link Layer
The data link layer consists of two sub-layers : * Logical Link Control (LLC) * Media Access Control (MAC).
802.11 uses the same 802.2 LLC and 48-bit addressing as other 802 LANs, allowing for very simple bridging from wireless to IEEE wired networks, but the MAC is unique to WLANs.
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802.11 Media Access Control
# Carrier Sense Medium Access with collision avoidance protocol (CSMA/CA)** Listen before talking** Avoid collision by explicit Acknowledgement
(ACK)** Problem: additional overhead of ACK packets, so
slow performance
# Request to Send/Clear to Send (RTS/CTS) protocol• Solution for “hidden node” problem• Problem: Adds additional overhead by
temporarily reserving the medium, so used for large size packets only retransmission would be expensive
# Power Management• MAC supports power conservation to extend the
battery life of portable devices• Power utilization modes
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Elements of a WI-FI Network
# Access Point (AP) - The AP is a wireless LAN transceiver or “base station” that can connect one or many wireless devices simultaneously to the Internet.
# Wi-Fi cards - They accept the wireless signal and relay information.They can be internal and external.(e.g PCMCIA Card for Laptop and PCI Card for Desktop PC)
# Safeguards - Firewalls and anti-virus software protect networks from uninvited users and keep information secure.
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How a Wi-Fi Network Works
# Basic concept is same as Walkie talkies.# A Wi-Fi hotspot is created by installing an
access point to an internet connection.# An access point acts as a base station. # When Wi-Fi enabled device encounters a
hotspot the device can then connect to that network wirelessly.
# A single access point can support up to 30 users and can function within a range of 100 – 150 feet indoors and up to 300 feet outdoors.
# Many access points can be connected to each other via Ethernet cables to create a single large network.
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Wi-Fi Network
Topologies# AP-based topology (Infrastructure Mode)
# Peer-to-peer topology (Ad-hoc Mode)
# Point-to-multipoint bridge topology 12
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AP-based topology# The client communicate through
Access Point. # BSA-RF coverage provided by an AP.# ESA-It consists of 2 or more BSA.# ESA cell includes 10-15% overlap to
allow roaming.
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Peer-to-peer
topology# AP is not required.# Client devices
within a cell can communicate directly with each other.
# It is useful for setting up of a wireless network quickly and easily. 14
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Point-to-multipoint bridge
topologyThis is used to connect a LAN in one building to a LANs in other buildings even if the buildings are miles apart . These conditions receive a clear line of sight between buildings. The line-of-sight range varies based on the type of wireless bridge and antenna used as well as the environmental conditions.
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Wi-Fi Configuratio
ns
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Wi-Fi Applications# Home
# Small Businesses or SOHO# Large Corporations &
Campuses# Health Care# Wireless ISP (WISP)#Travellers
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Wi-Fi Security TechniquesService Set Identifier
(SSID)Wired Equivalent Privacy (WEP)
802.1X Access ControlWireless Protected Access (WPA)
IEEE 802.11i18
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Service Set Identifier (SSID)
• SSID is used to identify an 802.11 network
• It can be pre-configured or advertised in beacon broadcast
• It is transmitted in clear text• Provide very little security
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Wired Equivalent Privacy (WEP)
Original security solution offered by the IEEE 802.11 standard
Uses RC4 encryption with pre-shared keys and 24 bit initialization vectors (IV)
key schedule is generated by concatenating the shared secret key with a random generated 24-bit IV
32 bit ICV (Integrity check value) No. of bits in keyschedule is equal to sum of length
of the plaintext and ICV 64 bit preshared key-WEP,128 bit preshared key-WEP2 Encrypt data only between 802.11 stations.once it enters the
wired side of the network (between access point) WEP is no longer valid
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802.1x Access Control• Designed as a general purpose network
access control mechanism• Authenticate each client connected to AP
(for WLAN) or switch port (for Ethernet) • Authentication is done with the RADIUS
server, which ”tells” the access point whether access to controlled ports should be allowed or not• AP forces the user into an unauthorized state • user send an EAP start message• AP return an EAP message requesting the user’s
identity• Identity send by user is then forwared to the
authentication server by AP 21
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Wireless Protected Access (WPA)# WPA is a specification of standard based,
interoperable security enhancements that strongly increase the level of data protection and access control for existing and future wireless LAN system.• User Authentication
• 802.1x • EAP
# TKIP (Temporal Key Integrity Protocol) encryption
• RC4, dynamic encryption keys (session based)• 48 bit IV• per packet key mixing function
• Fixes all issues found from WEP• Uses Message Integrity Code (MIC) Michael
• Ensures data integrity• Old hardware should be upgradeable to WPA# WPA comes in two flavors
• WPA-PSK• WPA Enterprise
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CONCLUSION Wi-Fi technology is the
non-cable connection between the access point or router and the PC. The PC remotely connects to the internet without any wires or cables. In some cases, Wi-Fi tech. requires you to have the WEP or WPA key to access. WEP/WPA is like the password to secure your wireless router/ access point.
# Advantages:• Mobility, Ease of
Installation• Flexibility, Cost• Reliability,Security• Use unlicensed part of the
radio spectrum, Speed
# Limitation:• Degradation in
performance• High power • consumption• Interference• Limited range
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REFERENCE# http://in.search.yahoo.com/search;_ylt=A8pWB_u3zVFPxVYAqUvuPXRG?ei=UTF-8&rd=r1&fr=yfp-t-704-s&p=wi-fi+technologies&SpellState=&fr2=sp-qrw-corr-top
http://sviehb.files.wordpress.com/2011/12/viehboeck_wps.pdf"Wi-Fi (wireless networking technology)". Encyclopedia Britannica. www.wikipedia.comwww.yahoo.comwww.Google.comwww.bing.com/image
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BIBLIOGRAPHY“Wi-Fi: What's next",
Paul S.HenryWireless Networking
Handbook, Jim Geier.Wi-Fi (wireless
networking technology)". Encyclopedia Britannica
Seoul Moves to Provide Free City-Wide Wi-Fi Service". Retrieved 1 April 2012
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THANK YOU