Lesson 5-Wireless Network

WIRELESS
NETWORK
INTRODUCTION TO WIRELESS
NETWORKS
• Wireless technology has helped to simplify networking
by enabling multiple computer users to simultaneously
share resources in a home or business without
additional or intrusive wiring.
• These resources might include a broadband Internet
connection, network printers, data files, and even
streaming audio and video.
Wireless Local Area Network
Connected to the Internet
Wireless Network Components
• Much like a traditional wired LAN, a WLAN is a

grouping of computers and peripheral devices that
share a common communications backbone.
• As is implied by the name, a WLAN allows users to
connect to the LAN wirelessly via radio transmission.
• Let us discuss some wireless network components
Access Point
• The access point is a device that links a

wireless network to a wired LAN.
• It increases the effective range of a
wireless network and provides additional
network management and security
features.
Access Point
• Wireless networks of three or fewer PCs do

not require an access point for adhoc
networking.
• Access points are useful for larger networks,
and they are particularly well-suited for
adding wireless capability to an existing
wired network.
PC Card
• A wireless PC card enables laptop users

to connect wirelessly to the LAN.
PCI Adapter
• Just as a wireless access PC card allows

portable and laptop computers access to
the LAN, a wireless access PCI adapter
allows desktop PC users access to the
LAN.
Router
• A router is a device used for sharing a single
Internet connection across multiple
computers.
• This is ideal in the home or office where
multiple computers and devices can be
online at the same time with only a single
Internet connection.
IEEE Wireless Networking Specifications
• The IEEE (Institute of Electrical and Electronic

Engineers) released the 802.11 specifications in June
1999.
• The initial specification, known as 802.11, used the
2.4 GHz frequency and supported a maximum data
rate of 1 to 2 Mbps.
• In late 1999, two new addenda were released.

• The 802.11b specification increased the
performance to 11 Mbps in the 2.4 GHz range
• The 802.11a specification utilized the 5 GHz
range and supported up to 54 Mbps.
• The two new specifications were incompatible

because they used different frequencies.
• This means that 802.11a network interface cards
(NICs) and access points cannot communicate
with 802.11b NICs and access points.
• This incompatibility forced the creation of the new draft standard
known as 802.11g.
• The 802.11 specifications were developed specifically for Wireless
Local Area Networks (WLANs) by the IEEE and include four subsets
of Ethernet-based protocol standards:
• 802.11,
• 802.11a( known as WI-FI5)
• 802.11b(known as WI-FI) and
• 802.11g.
WIFI
WIFI
• WiFi stands for Wireless Fidelity.
• WiFi is based on the IEEE 802.11 family
of standards and is primarily a local area
networking (LAN) technology.
• designed to provide in-building
broadband coverage.
WIFI
• WiFi has become the de facto standard for last

mile broadband connectivity in homes, offices,
and public hotspot locations.
• Systems can typically provide a coverage range
of only about 1,000 feet from the access point.
WIFI – WORKING CONCEPTS
• Radio Signals are the keys, which make Wi-Fi

networking possible.
• These radio signals transmitted from Wi-Fi antennas
are picked up by Wi-Fi receivers, such as computers
and cell phones that are equipped with Wi-Fi cards.
WIFI – WORKING CONCEPTS
• Whenever, a computer receives any of the signals

within the range of a Wi-Fi network, which is
usually 300 — 500 feet for antennas,
• the Wi-Fi card reads the signals and thus creates an
internet connection between the user and the
network without the use of a cord.
Different WLAN Technologies
• As various wireless networking technologies have advanced
over time, several WLAN technologies have emerged,
including:
• narrowband,
• spread spectrum,
• frequency hopping spread spectrum, and
• Direct sequence spread spectrum.
Narrowband
• As the name suggests, narrowband

technology uses a specific radio
frequency for data transmission.
Spread Spectrum
• Originally developed for military use.
• spread spectrum technology allows for greater bandwidth by
continually altering the frequency of the transmitted signal,
• thus spreading the transmission across multiple frequencies.
• Spread spectrum uses more bandwidth than narrowband, but
the transmission is more secure, reliable, and easier to detect.
Frequency Hopping Spread Spectrum
(FHSS)
• Constantly changing from one frequency to another,
transmitting data for a certain period of time before
changing frequency again.
• Like spread spectrum technology, FHSS technology
consumes additional bandwidth.
• however, this is over the course of multiple carrier
frequencies.
Direct Sequence Spread Spectrum (DSSS)
• Direct sequence spread spectrum (DSSS)
technology breaks down the transmitted stream
of data into small pieces across a frequency
channel.
• DSSS technology uses more bandwidth than
FHSS, but DSSS is considered more reliable and
resists interference.
WLAN Performance
• Much the same way a cordless phone works better when it is

close to its base,
• wirelessly networked computers function best when located
relatively close together and in open sight of each other.
• The level of performance of an 802.11 WLAN is dependent
on a number of important environmental and product-specific
factors.
Factors that Affect WLAN
Performance
• Access points will automatically negotiate the
appropriate signaling rate based upon environmental
conditions, such as:
• Distance between WLAN devices( Access Point and
Network Interface Card)
• Transmission power levels
Factors that Affect WLAN
Performance
• Building and home materials
• Radio frequency interference
• Signal propagation
• Antenna type and location(type - directional and
omnidirectional)
WIFI TOPOLOGIES
WIFI Topologies
• Peer-to-peer topology (Ad-hoc Mode)

• AP-based topology (Infrastructure
Mode)
Peer-to-peer Topology
• Access Point is not required.
• Client devices within a cell can communicate with
each other directly.
• Similar to using your smartphone to create a Wi-Fi
hotspot.
• It is useful for setting up a wireless network quickly
and easily.
AP-based topology (Infrastructure Mode)
• The client communicate through Access Point(AP).

• Any communication has to go through AP.
• If a Mobile Station (MS), like a computer, a PDA, or a
phone, wants to communicate with another MS,
• it needs to send the information to AP first, then AP sends
it to the destination MS.
HOTSPOTS
Hotspots
• A Hotspot is a geographical area that has a readily
accessible wireless network.
• Hotspots are equipped with Broadband Internet
connection and one or more Access points that allow
users to access the internet wirelessly.
• Hotspots can be setup in any public location that can
support an Internet connection.
How a Wi-Fi Network Works
• 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.
Advantages
• Mobility
• Ease of Installation
• Flexibility
• Cost
• Reliability
Advantages
• Security
• Use unlicensed part of the radio spectrum
• Roaming
• Speed
Limitations
• Interference
• Degradation in performance
• High power consumption
• Limited range
Wi-Fi SECURITY
TO BE DISCUSSED UNDER NETWORK SECURITY
Conclusion
• Wi-Fi is a simple and cost effective way to

connect to internet without the need of
wires.
• It is growing in popularity because of
decreasing costs and the freedom it gives to
users.

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WIRELESS

• Much like a traditional wired LAN, a WLAN is a

• The access point is a device that links a

• Wireless networks of three or fewer PCs do

• A wireless PC card enables laptop users

• Just as a wireless access PC card allows

• The IEEE (Institute of Electrical and Electronic

• In late 1999, two new addenda were released.

• The two new specifications were incompatible

• WiFi has become the de facto standard for last

• Radio Signals are the keys, which make Wi-Fi

• Whenever, a computer receives any of the signals

• As the name suggests, narrowband

• Much the same way a cordless phone works better when it is

• Peer-to-peer topology (Ad-hoc Mode)

• The client communicate through Access Point(AP).

• A Wi-Fi hotspot is created by installing an access

• Wi-Fi is a simple and cost effective way to

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