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.
• Safeguards - Firewalls and anti-virus software
protect networks from uninvited users and keep
Wi-Fi's Radio Technology:
WiFi radios that work with the 802.11b and 802.11g
standards transmit at 2.4 GHz, while those that work
with the 802.11a standard transmit at 5 GHz. Normal
walkie-talkies normally operate at 49 MHz. The
higher frequency allows higher data rates.
WiFi radios use much more efficient coding
techniques that also contribute to the much higher
data rates. For 802.11a and 802.11g, the technique is
known as orthogonal frequency-division multiplexing
(OFDM). For 802.11b, it is called Complementary
Code Keying (CCK).
Wi-Fi's Radio Technology:
The radios used for WiFi have the ability to change
frequencies. 802.11b cards can transmit directly on
any of three bands, or they can split the available
radio bandwidth into dozens of channels
and frequency hop rapidly between them. The
advantage of frequency hopping is that it is much
more immune to interference and can allow dozens
of WiFi cards to talk simultaneously without
interfering with each other.
Radio Signals are the keys which make WiFi
networking possible. These radio signals transmitted
from Wi-Fi antennas are picked up by WiFi receivers
such as computers and cell phones that are equipped
with WiFi cards. Whenever a computer receives any
of the signals within the range of a WiFi network
which is usually 300 - 500 feet for antennas, the WiFi
card will read the signals and thus create an internet
connection between the user and the network
without the use of a cord.
Access points which consist of antennas and routers
are the main source which transmit and receive radio
WiFi cards can be external or internal, meaning that if
a WiFi card is not installed in your computer, you may
purchase a USB antenna attachment and have it
externally connect to your USB port, or have an
antenna-equipped expansion card installed directly to
the computer. For laptops, this card will be a PCMCIA
card in which you insert to the PCMCIA slot on the
A Wi-Fi hotspot is created by installing an access
point to an internet connection. The access point
transmits a wireless signal over a short distance .
typically covering around 300 feet. When a Wi-Fi
.enabled device, such as a Pocket PC, encounters a
hotspot, the device can then connect to that network
Adding WiFi to a Computer
Take a 802.11a, 802.11b or 802.11g network card.
802.11g has the advantage of higher speeds and good
interoperability on 802.11b equipment.
For a laptop, this card will normally be a PCMCIA
card that slide into a PCMCIA slot on laptop. Or
take a small external adapter and plug it into a
For a desktop machine, take a PCI card & install
inside the machine, or a small external adapter
and connect to the computer with a USB cable.
Install the card
Install the drivers for the card
Find an 802.11 hotspot
Access the hotspot.
• 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.
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.
Point-to-multipoint bridge 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.
Wi-fi is a simple, cost-effective way to connect to the
Internet , Without the need to physically connecting
Hotspot s a geographic area setup in any public
location, and has a readily accessible wireless
Security is a huge challenge for Wi-Fi Networks, many
Security Techniques are used to improve it.
The Future of Wi-Fi
The future of Wi-Fi is very bright. Its growing in
popularity because of decreasing cost and the
freedom it gives to users.
802.11ac: The Fifth Generation of Wi-Fi Technical White Paper
Impact of wireless technology