By MD MONIRUZZAMAN DEPT:-ECE 3RD YEAR WBUT ROLL NO: 09148003059

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PRESENTATION ON WI-FI TECHNOLOGY

-: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

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

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

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

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

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