Origin and meaning of the term
• The term "Wi-Fi" suggests "Wireless
Fidelity", comparing with the long-
established audio recording term
"High Fidelity" or "Hi-Fi", and
"Wireless Fidelity" has often been
used in an informal way, even by the
Wi-Fi Alliance itself, but officially the
term does not mean anything.
• The precursor to Wi-Fi was invented in 1991
by NCR Corporation/AT&T (later Lucent &
Agere Systems) in Nieuwegein, the
Netherlands.The first wireless products were
brought on the market under the name
WaveLAN with speeds of 1 Mbit/s to 2 Mbit/s.
Vic Hayes, who held the chair of IEEE 802.11
for 10 years and has been named the 'father
of Wi-Fi,' was involved in designing standards
such as IEEE 802.11b, and 802.11a.
Wi-Fi is one of the wireless technologies
based on IEEE 802.11
Wi-Fi is a global set of standards. Unlike
mobile telephones, any standard Wi-Fi
device will work anywhere in the world.
What Is Wi-Fi ?
Types of Wireless
Peer to peer (Ad-hoc)
Comparison between wireless
• Wired network
• Wired networking requires cables to be
• Cost of wire networking is less.
• Wired network can offer 100Mbps
• Ethernet cables switches and hubs used
• Firewallls are not supported by ethernet
hubs & switches.
• It is a tedious to expand the wired
• Wireless network
• Installing a wireless network is quite
• Wireless network requires equipment like
wireless adapter & access point which
• Maximum bandwidth provided by
wireless network is 11Mbps.
• Wireless networking is less reliable.
• WEP encription makes wireless network
as secure as wired network.
• Mobility of wireless network is better
than wired network.
802.11a 802.11b 802.11g
Frequency Compatibility Description
802.11 2 Mbps 46 m 2.4 GHz 802.11 The original wireless
802.11a 54 Mbps 46 m 5 GHz 802.11a Products are wi-fi
available channel &
less prone to
802.11b 11 Mbps 91 m 2.4 GHz 802.11b Products are wi-fi
802.11g 54 Mbps 91 m 2.4 GHz 802.11b,802.
Products are wi-fi
Access Point & Extention Point
Hardware Access Point
Software Access Points
Wireless & Power-line bridges
• A wireless network uses radio waves, just like
cell phones, televisions and radios do. In fact,
communication across a wireless network is a lot
like two-way radio communication. Here's what
• A computer's wireless adapter translates data
into a radio signal and transmits it using an
• A wireless router receives the signal and
decodes it. The router sends the information
to the Internet using a physical, wired
• The process also works in reverse, with the
router receiving information from the Internet,
translating it into a radio signal and sending it
to the computer's wireless adapter.
If you want to take advantage of public WiFi hotspots
or start a wireless network in your home, the first thing
you'll need to do is make sure your computer has the
right gear. Most new laptops and many new desktop
computers come with built-in wireless transmitters. If
your laptop doesn't, you can buy a wireless adapter
that plugs into the PC card slot or USB port. Desktop
computers can use USB adapters, or you can buy an
adapter that plugs into the PCI slot inside the
computer's case. Many of these adapters can use more
than one 802.11 standard.
The purpose of Wi-Fi is to provide
interoperable wireless access to
digital content. This content may
include applications, audio and visual
media, Internet connectivity, or
other data. Wi-Fi generally makes
access to information between
devices from different manufacturers
easier, as it can eliminate some of
the physical restraints of wiring; this
can be especially true for mobile
devices. The meaning of Wi-Fi was
originally "wireless-fireless" because
of it's speed, but this is seldom used
• A Wi-Fi enabled device such as a PC, game
console, mobile phone, MP3 player or PDA
can connect to the Internet when within
range of a wireless network connected to the
Internet. The coverage of one or more
interconnected access points — called a
hotspot — can comprise an area as small as
a single room with wireless-opaque walls or
as large as many square miles covered by
overlapping access points. Wi-Fi technology
has served to set up mesh networks, for
example, in London. Both architectures can
operate in community networks.
1> Wired Equivalent Privacy (WEP)
2>Wi-Fi Protected Access (WPA)
Service Set Identifier (SSID)
Media Access Control (MAC) address
Port Based Access Control