This document provides an overview of Wi-Fi, including its history, standards, topologies, security, advantages, disadvantages, applications, and future. It discusses how Wi-Fi works using radio frequencies to connect devices wirelessly. Key standards include 802.11a, b, g, and n, with newer versions providing higher speeds and improved security. Wi-Fi is commonly used both privately and publicly to access the internet via routers and hotspots.

1. Wi-Fi

2. CONTENTS
 Introduction
 History
 What is Wi-Fi
 How Wi-Fi works
 Wi-Fi Standards
 Topologies
 Security
 Advantages
 Disadvantages
 Application
 Conclusion
 Future

3. INTRODUCTION
• Wi-Fi is the wireless way to handle
networking.
• 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 WLANs.

4. HISTORY OF Wi-Fi
• The precursor to Wi-Fi was invented in 1991
by NCR Corporation with AT&T Corporation in
Nieuwegein, the Netherland.
• The first wireless products were brought on
the market under the name WaveLAN with
speeds of 1Mbit/s to 2Mbit/s.
• Vic Hayes has been named as father of
“Wi-Fi”.

5. HISTORY OF Wi-Fi
• In 1992 and 1996, Australian organization
CSIRO obtained patents for a method later
used in Wi-Fi.
• In April 2009, 14 tech companies agreed to
pay CSIRO $250 million for infringements on
CSIRO patents
• As of 2010, the Wi-Fi Alliance consisted of
more than 375 companies from around the
world.

6. How Wi-Fi works

7. Wi-Fi Standards
802.11a
Runs in the 5 GHz range
Uses OFDM technology
Has 12 channels, 8 non-overlapping, and
supports rates up to 54Mbps
Flexible because multiple channels can be
combined for faster throughput and more
access points can be collocated

8. Wi-Fi Standards
802.11b
• Runs in the 2.4 GHz frequency range
• Use DSSS technology
• Has 11 channels, with 3 non-overlapping
and supports up to 11 Mbps

9. Upcoming standards
• 802.11g : Backwards compatible with 802.11b
with the same disadvantage
• 802.11b+ : Backwards compatible with
802.11b supports rates up to 22 Mbps
• 802.11i : Provides more security by advance
encryption technology.
• 802.11e : More multimedia friendly for
viewing streaming videos.

10. Wi-Fi Standards
• IEEE 802.11n:
 Introduced in 2003
 100-150 feet range
140 Mbps Speed 54Mbps (actual speed)
 2.4 GHz
Outdoor ranges 2000 feet

11. Range & performance
• 802.11a
-Indoor 40-300 feet
-outdoor 100 to 1000 feet
• 802.11b
-Indoor 100-300 feet
-outdoor 400 to 1500 feet

12. Wi-Fi Topologies
AP-based topology
• Peer-to-peer topology
• Point-to-multipoint bridge topology

13. About radio frequency
• There is no wire connection between sender
& receiver.
• Two types RF is used-
• 1-Direct sequence spread spectrum radio
technology.
• 2-Orthogonal frequency division multiplexing

14. Typical community Wi-Fi
Constituents
• Sector antenna
• Other components
• Customer premises equipment
• High gain parabolic grid antennas

15. A sticker indicating to the public that a
location is within range of a Wi-Fi
network. A dot with curved lines
radiating from it is a common symbol
for Wi-Fi, representing a point
transmitting a signal.

16. CITY-WIDE WI-FI
In 2004, Mysore became India's first Wi-Fi-enabled city and
second in the world after Jerusalem.
In 2005, Sunnyvale, California, became the first city in the
United States($44)

17. An embedded RouterBoard
Wireless routers integrate a Wireless Access Point.
A wireless router allows wired and wireless Ethernet
LAN devices to connect to a single WAN device such as
cable modem or a DSL modem.

18. USB wireless adapter
Wireless adaptor allow devices to connect to a wireless
network. These adapters connect to devices using
various external or internal interconnects such as PCI,
miniPCI, USB, Express Card, Cardbus and PC card. As
of 2010, most newer laptop computers come equipped
with built in internal adapters.

19. Wi-Fi in Your Life
Wi-Fi uses radio waves to create reliable high-
speed connections between computers, printers,
gaming devices, cameras phones and home
entertainment systems. You can use Wi-Fi in your
home, at work or on-the-go at hotspots
worldwide.

20. Why Wi-Fi
• Setup cost –reduced cabling required
• Flexibility – quick and easy to setup
• Scalability – can be expanded with growth
• Freedom – you can work from any location

21. Operating modes
• Infrastructure Mode
• AD HOC Mode

22. Wi-Fi Threats
• Eavesdropping(sniffers, protocol analyzers
Password collectors)
• MITM Attack(change AP)
• Denial of services(freq.)

23. Wi-Fi Security
• Authentication User Server Privacy
• Authentication:
Authentication Keeping unauthorized users off
the network User Authentication Server is used
Username and password Risk: Data (username &
password) send before secure channel
established Prone to passive eavesdropping by
attacker Solution Establishing a encrypted
channel before sending username and password .

24. SECURITY
• Data Security/Encryption
• WEP-Shared key&ICV
• SSID
• WPA(TKIP&PSK)

25. Capabilities and uses
• Online video conferencing with greater clarity
• Telephony ,using VoIP
• Broadband in the true sense
• Easier reach into far-flung rural areas
• Ability to add more nodes as and when
required

26. Advantages
• Wi-Fi can make access publically available at Wi-
Fi hotspots.
• Does not require regulatory approval for
individual.
• Wi-Fi network can support roaming.
• Wi-Fi allows local area network to deployed
without wires for client devices.
• High data transmission rate
• High reliable
• Good network

27. Advantages
• It’s also suitable for high bandwidth
• Less maintenance
• Mobile
• Relatively inexpensive
• Easy to set up a network
• User-friendly software
• Security features
• Global set of standards.

28. Disadvantage of 802.11a
As this standard does not support frequency
hoping in response to interference it
retransmits or wait for the higher level TCP/IP
protocol to sort out signal from noise.
This works well for data transmission but can
result in voice transmission.

29. Disadvantage of 802.11b
• It is prone to interference from other devices
(microwave ovens, cordless phones, etc) and
also has security disadvantages
• It limits to the number of access points in
range of each other

30. DISADVANTAGE OF Wi-Fi
Interference
Limited range degradation in
performance
High power
consumption

31. APPLICATION OF Wi-Fi
• Home
• Small Businesses
• Large Corporations
• Campuses
• Health Care
• Educational
• Institutions
• Banks

32. FUTURE
• Wi-Fi enables wireless voice-applications
(VoWLAN or WVOIP). Over the years, Wi-Fi
implementations have moved toward "thin"
access points, with more of the network
intelligence housed in a centralized network
appliance, relegating individual access points
to the role of "dumb" transceivers. Outdoor
applications may utilize mesh topologies.