2. CONTENT
What is Wi-Fi network ?
Why we need Wi-Fi network ?
How a Wi-Fi network works ?
Advantages and disadvantages of Wi-Fi
Elements of Wi-Fi network
Technologies of Wi-Fi network
Topologies of Wi-Fi network
Applications of Wi-Fi network
Security threats of Wi-Fi network
Wi-Fi network security
Limitations of Wi-Fi network
Summery

3. What is a Wi-Fi network
 Wi-Fi is the name of a popular wireless
networking technology that uses radio
waves to provide wireless high-speed
Internet and network connections.
 In other words, Wi-Fi is a technology
that allows an electronic device to
exchange data or connect to the
internet wirelessly using 2.4 GHz UHF
and 5 GHz SHF radio waves.

4. Why we need Wi-Fi?
The purpose of Wi-Fi is to hide complexity by
enabling wireless access to applications
and data, media and streams.
The main aims of Wi-Fi are the following:
 make access to information easier
 ensure compatibility and co-existence of
devices
 eliminate complex cabling
 eliminate switches, adapters, plugs, pins
and connectors

5. How Wi-Fi works
A Wi-Fi network uses electromagnetic waves
to transmit data across a wireless network,
like a two-way radio.
A Wireless router, or access point acts as a
central hub that other wireless devices can
connect to (either for connecting to the
internet, or sharing data between devices
on the same network).

6.  Using a bunch of clever data compression
techniques data is converted to radio
waves, like cell phones and OTA (over the
air) TV signals, sent from one device to the
other through the air then converted
back into data.
 It is important to note that Wireless
devices are capable of two-way
communication; they can both send and
receive wireless data.

7. Advantages of Wi-Fi
Mobility
Ease of Installation
Flexibility
Cost
Reliability
Security
Use unlicensed part of the radio spectrum
Roaming
Speed

8. Disadvantages of Wi-Fi
 Wi-Fi can be less secure than wired
connections.
 To no longer the use of Wi-Fi band is
2.4GHz does not require a license in
most countries provided that is stays
below limit of 100mW
 And one accepts interference from
other sources; including interference
which causes the user devices
function.

9. Elements of Wi-Fi
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.
Safe guards - Firewalls and anti-virus
software protect networks from uninvited
users and keep information secure.

10. The Wi-Fi Technology
TECHNOLOGI
ES
IEEE 802.11b
IEEE 802.11a
IEEE 802.11g

11. IEEE 802.11b
Appear in late 1999
Operates at 2.4GHz radio spectrum
11 Mbps (theoretical speed)- within 30m
range
4-6 Mbps (actual speed)
100-150 feet range

12. Most popular
Least expensive
Interference from mobile phones
and Bluetooth devices which can
reduce the transmission speed

13. IEEE 802.11a
Introduced in 2001
Operates at 5GHz (less popular)
54Mbps (theoretical speed) & 15-20Mbps
(actual speed)
50-75 feet range
More expensive
Not compatible with IEEE802.11b

14. IEEE802.11g
Introduced in 2003
Combined the features of both standards
(a,b)
100-150 feet range
2.4GHz radio frequencies
Compatible with ‘b’

15. Topologies of Wi-Fi
Wi-Fi
topologies
AP based
Peer-to-peer
Point-to-multipoint

16. AP based topology
(Infrastructure mode)
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.

17. Peer-to-peer topology
(ad-hoc mode)
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.

18. Point-to-multipoint topology
 This 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.

19. Applications of Wi-Fi network
 Home
 Small business
 Large corporations and campus
 Health care
 Wireless ISP (WISP)
 Travelers

20. Security threats of Wi-Fi
 Eavesdropping
 Man-in-the-middle attack
 Denial of service

21. Eavesdropping
 Eavesdropping is secretly listening to
the private conversation of others
without their consent.
 Eavesdropping can also be done over
telephone lines (wiretapping), email,
instant messaging, and other methods
of communication considered private.

22. Man-in-the-middle attack
 The man-in-the-middle attack in
cryptography and computer security is a
form of active eavesdropping in which
the attacker makes independent
connections with the victims and relays
messages between them, making them
believe that they are talking directly to
each other over a private connection,
when in fact the entire conversation is
controlled by the attacker.

23.  A man-in-the-middle attack can succeed
only when the attacker can impersonate
each endpoint to the satisfaction of the
other; it is an attack on mutual
authentication.

24. Denial of service
 In computing, a denial-of-service (DoS) or
distributed denial-of-service (DDoS) attack is
an attempt to make a machine or network
resource unavailable to its intended users.
 Perpetrators of DoS attacks typically target
sites or services hosted on high-profile web
servers such as banks, credit card payment
gateways, and even root name servers.

25.  One common method of attack involves
saturating the target machine with
external communications requests, so
much so that it cannot respond to
legitimate traffic or responds so slowly as
to be rendered essentially unavailable.

26. Wi-Fi network security
Authentication is the act of
confirming the truth of an attribute
of a single piece of data (datum) or
entity.
Authentication is the process of
actually confirming that identity.

27. It might involve confirming the identity of a
person by validating their
identity documents,
verifying the validity of a website with a
digital certificate,
tracing the age of an artifact by carbon
dating,
 ensuring that a product is what its
packaging and labeling claim to be.
In other words, Authentication often involves
verifying the validity of at least one form of
identification.

28. Limitations of Wi-Fi
Interference
Degradation in performance
High power consumption
Limited range

29. CONCLUSION
Thus, the simple to use Wi-Fi technology is
finding a wide range of applications in
various fields and is revolutionizing wireless
communication.
Both technology and skills goes hand-in-
hand, those who can design better
architecture of networks can lead Wi-Fi
networks.
Wireless Fidelity is common now.
We are expecting more on this technology
in future.
Let’s hope for that. . .