WI – FI TECHNOLOGY
S.RAVI KIRAN REDDY (III YR ECE)
SUBBURAJAN.C (III YR ECE)
WIRELESS FIDELITY (Wi-Fi) is the term used for a high frequency wireless local area
network. WI-FI is a way to get internet access through unlicensed spectrum and an alternative to
wired LAN.WI-FI refers to a set of networking technologies specifically 802.11b,802.11a and
802.11g standards. The Wi-Fi networks operate in the 2.4 GHz and 5 GHz radio bands, with 11
Mbps or 54 Mbps data rate.
Wi-Fi standards are fast enough to allow a broadband connection. It is an emerging technology
that adds tremendous levels of convenience and increased productivity. The strength of WI-FI is
that it leaves connection criteria and roaming totally open to the client. They connect Wireless
Access Points (WAP) to their network backbone to provide Internet and network access.
Wi-Fi assures that the Wi-Fi CERTIFIED equipment we purchase today will work with the
equipment we add to our network in future. The extension of Wi-Fi is WIMAX that provides
high-throughput broadband connections over long distances. Wi-Fi, a global set of standards, is
widely available in more than 250,000 public hot spots and millions of homes and corporate and
university campuses worldwide. Thus the free Wi-Fi is considered to be the future of the
INTRODUCTION TO WI-FI
Wireless Fidelity (Wi-Fi) allows us to connect to the Internet from our couch
at home, a bed in a hotel room or a conference room at work without wires. Wi-Fi is a
wireless technology like a cell phone. Wi-Fi enabled computers send and receive data
indoors and out; anywhere within the range of a base station. And the best thing of all, it's
fast. In fact, it's several times faster than the fastest cable modem connection.
WI-FI TECHNOLOGY CONNECTS YOU ANY WHERE:
Imagine working on our laptop or checking e-mail from anywhere in our
home. Imagine being able to connect to our office network from an airport or coffee
shop. Imagine retrieving files or presentations from the corporate network, cruising the
Internet or sending instant messages to co-workers—and doing it all from a conference
room or the company criteria.
Now, imagine doing all these things easily and quickly - without worrying about finding
a wired network connection. That is Wi-Fi.
It's powerful. Wi-Fi networks use radio technologies called IEEE
802.11b or 802.11a to provide secure, reliable, fast wireless connectivity. A Wi-Fi
network can be used to connect computers to each other, to the Internet, and to wire
networks (which use IEEE 802.3 or Ethernet). Wi-Fi networks operate in the unlicensed
2.4 and 5 GHz radio bands, with an 11 Mbps (802.11b) or 54 Mbps (802.11a) data rate or
with products that contain both bands (dual band), so they can provide real-world
performance similar to the basic 10BaseT wired Ethernet networks used in many offices.
WHO COULD USE WI-FI:
Everyone can use Wi-Fi, almost everywhere in the world. Home Wi-Fi
networks can connect multiple computers to each other, to peripherals, and to the
Internet. A Wi-Fi network can connect a family's computers together to share such
hardware and software resources as printers and the Internet. That means everyone in the
family can share stored files, photos and documents and print them out on a single printer
attached to one desktop computer—all without unsightly cables running throughout the
home. In a home or home office, using Wi-Fi CERTIFIED equipment in our wireless
network gives us the ability to share a single high-speed broadband cable or DSL
connection. A Wi-Fi network can easily be expanded to ten users or more.
It also gives us assurance that the Wi-Fi CERTIFIED equipment we purchase
today will work with the equipment we add to our network in the future.
Commercial Wi-Fi services are available in places such as Internet cafes,
coffee houses and airports around the world, although coverage is patchy in comparison
Wi-Fi VS CELLULAR:
Wi-Fi and related consumer technologies hold the key to replacing cellular
telephone networks such as GSM. Some obstacles to this happening in the near future are
missing roaming and authentication features the narrowness of the available spectrum
and the limited range of Wi-Fi. Despite such problems.
The term 4G is occasionally used for Wi-Fi, the implication being that the
bandwidth and capabilities offered are already greater than those promised by the 3G
cellular telephone standards.
The main difference between cellular and Wi-Fi is that cellular system
use licensed spectrum, and Wi-Fi is implemented in unlicensed bands. The economic
basis for their implementation is therefore completely different. The success of Wi-Fi has
made many people look to unlicensed spectrum as the future of wireless access, rather
than spectrum licensed and controlled by large corporations.
COMPARISON WIFI AND OTHER NETWORKS:
No other networking technology used to set up a small home or SOHO
network provides the convenience or mobility of a Wi-Fi network. That's because other
methods, including standard wired Ethernet networks and phone line- and power line-
based networks, all require a connection via wire or cable. Wi-Fi uses radio waves that
travel through walls and floors and connect you anywhere, indoors or out.
Networks based on phone lines, also called Home PNA, must have a phone
jack close to the computer or peripheral that is to be networked with the rest of our
system. We may have problems with this type of network based on the quality of our
phone line installation and especially if we have numerous phone devices plugged into
each wall jack.
Networks based on power lines, also called HomePlug, have location
problems, too. Of course, there are many more power outlets in a home than there are
phone plugs, but power plugs may not be where we need them when we need them,
Power line networks are often more expensive than Wi-Fi based
equipment. Power line networks can experience interference from transformers, large
appliances, power strips, surge protectors and even common "wall warts" (DV power
These technologies don't allow us to just pick up our laptop or PDA and go
anywhere in our home or small office and begin working or continue working in another
location without losing contact with your network. Working outside on our patio or next
to the pool is impossibility.
IS WIFI OR WIRED NETWORK IS BEST:
If we are using mostly desktop computers, a wired network may work fine.
However, for mobility, modifications and growth, Wi-Fi provides the best answer
because it enables us to move the computers anywhere in the building where they can
connect to the wireless network. If we or our company move to a new location, we don't
need to leave our cables, cable drops and other network investments behind. The entire
wireless network comes with us and takes only moments to set up in a new location.
Obviously if we are using laptop computers and/or other kinds of mobile
computing devices, Wi-Fi is the only answer for both home and business.
To see the variety of ways we can hook up a home or small office to create
a wireless or combined wired/wireless network, go to SOHO — Small Office — Home
Office Networking Configurations.
EXTENSION OF WIFI:
WiMAX is a standards-based wireless technology that provides high-
throughput broadband connections over long distances. WiMAX can be used for a
number of applications, including "last mile" broadband connections, hotspots and
cellular backhaul, and high-speed enterprise connectivity for business.WiMax does not
conflict with WiFi but actually complements it.
TECHNICAL ADVANTAGES OF WIFI:
WiMAX is a wireless metropolitan area network (MAN) technology that
will connect 802.11(WiFi) hotspots to the Internet and provide a wireless extension to
cable and DSL for last mile (last km) broadband access. 802.16 provides up to 50 km (31
miles) of linear service area range and allows users connectivity without a direct line of
sight to a base station. The technology also provides shared data rates up to 70 Mbit/s,
which, according to WiMax proponents, is enough bandwidth to simultaneously support
more than 60 businesses with T1-type connectivity and hundreds of homes at DSL-type
An important aspect of the 802.16 is that it defines a MAC layer that supports
multiple physical layer (PHY) specifications. This is crucial to allow equipment makers
to differentiate their offerings.
EXPECTATIONS Metropolitan area, making that area into a WIMAX and
allowing true wireless mobility within it, as opposed to hot-spot hopping required
by WiFi. The proponents are WiMax is referred to as "WiFi on steroids". It has
the potential to enable even more millions to access the internet wirelessly,
cheaply and easily. The WiMax wireless coverage is in square km (miles) while
that of WiFi is in the medium range. A WiMax base station would beam high-
speed Internet connections to homes and businesses in a radius of up 50 km (30
miles); these base stations will eventually beam to an entire hoping that the
technology will eventually be used in notebook computers and PDAs. Although true
roaming cell-like wireless broadband is IEEE standard 802.20, which is
compatible with WiMAX.
Bit of the brodcast spectrum, this means less regulatory controls in many countries.
Frees network devices from cables, allows for Uses an unlicensed a more dynamic
network to be grown.
Many reliable and bug-free Wi-Fi products on the market.
Competition amongst vendors has lowered prices considerably since their inception.
While connected on a Wi-Fi network, it is possible to move about without breaking the
The 802.11b and 802.11g flavors of Wi-Fi use the 2.4 GHz spectrum, which is crowded
with other devices such as
DISADVANTAGES OF WIFI :
Bluetooth, microwave ovens, cordless phones (900 MHz or 5.8 GHz are, therefore,
alternative phone frequencies one can use if one has a Wi-Fi network), or video sender
devices, among many others. This may cause a degradation in performance. Other
devices which use microwave frequencies such as certain types of cell phones can also
cause degradation in performance.
Power consumption is fairly high compared to other standards, making battery life and
heat a concern.
It is not always configured properly by users. In addition, Wi-Fi commonly uses WEP
(Wired Equivalent Privacy) protocol for protection, which has been shown to be easily
breakable even when properly configured. Newer wireless solutions are slowly providing
support for the superior WPA (Wi-Fi Protected Access) protocol (a preliminary
implementation of the 802.11i protocol), though many systems still employ WEP. The
adoption of the 802.11i (aka WPA2) protocol in June 2004 makes available a rather
better security scheme for future use — when properly configured.
Wi-Fi networks have limited range. A typical Wi-Fi home router using 802.11b or
802.11g might have a range of 150 ft (46 m) indoors and 300 ft (92 m) outdoors. But
about 10 US$ and an hour of building will get you an antenna that can go much further.