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Wi-Fi is a trademark of the Wi-Fi Alliance thatmanufacturers may
use to brand certified productsthat belong to a class of wireless
local areanetwork(WLAN)
The term WI-FI suggests wireless fidelity ,resembling the
long-established audio-equipmentclassification term high fidelity
or HI-FI (used since1950). Even the WI-FI Alliance itself has often
usedthe phrase wireless fidelity in its press releases
and documents the term also appears in a whitepaper on Wi-Fi
from. However, based on PhilBelangers statement, the term Wi-Fi was
neversupposed to mean anything at all.
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Wi-Fi would certainly not exist without adecision taken in 1985
by the FederalCommunications Commission (FCC),America's telecoms
regulator, to open several
bands of wireless spectrum, allowing them tobe used without the
need for a governmentlicense.
But the FCC, prompted by a visionaryengineer on its staff,
Michael Marcus, tookthree chunks of spectrum from the
industrial,scientific and medical bands and openedthem up to
communications.
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A Wi-Fi enabled device such as a personalcomputer, video game
console, Smartphone ordigital audio player can connect to the
Internetwhen within range of a wireless network
connected to the Internet.The coverage of one or more
(interconnected)
access points called hotspots can comprisean area as small as a
few rooms or as large as
many square miles. Coverage in the largerarea may depend on a
group of access pointswith overlapping coverage. Wi-Fi
technologyhas been used in wireless mesh networks.
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In addition to private use in homes andoffices, Wi-Fi can
provide public access atWi-Fi hotspots provided either free-of-
charge or to subscribers to variouscommercial services.
Organizations andbusinesses such as those runningairports, hotels
and restaurants - often
provide free-use hotspots to attract orassist clients.
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Routers that incorporate a digital subscriberline modem or a
cable modem and a Wi-Fiaccess point, often set up in homes and
otherpremises, can provide Internet access and
internetworking to all devices connected(wirelessly or by cable)
to them. With theemergence of MiFi and WiBro (a portable Wi-Fi
router) people can easily create their ownWi-Fi hotspots that
connect to Internet via
cellular networks. Now many mobile phonescan also create
wireless connections viatethering on iPhone, Android, Symbian,
andWinMo
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In the early 2000s, many cities around theworld announced plans
for city-wide Wi-Finetworks. This proved to be much more
difficult than their promoters initiallyenvisioned with the
result that most ofthese projects were either canceled orplaced on
indefinite hold. A few were
successful, for example in 2005,Sunnyvale, California became the
first cityin the United States to offer city-wide freeWi-FI
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Carnegie Mellon University built the firstwireless Internet
network in the world attheir Pittsburgh campus in 1994,long
before Wi-Fi branding originated in 1999.Most campuses now have
wirelessInternet.
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Wi-Fi also allows communications directlyfrom one computer to
another without theinvolvement of an access point. This is
called thead-hoc
mode of Wi-Fitransmission. This wireless ad-hoc networkmode has
proven popular with multiplayerhandheld game consoles.
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As of 2010 Wi-Fi technology has spreadwidely within business and
industrial sites.In business environments, just like other
environments, increasing the number ofWi-Fi access points
provides networkredundancy, support for fast roaming andincreased
overall network-capacity by
using more channels or by definingsmaller cells. Wi-Fi enables
wireless voice-applications
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Wi-Fi networks have limited range. A typical WIRELESSROUTER
using 802.11b or 802.11g with a stock antennamight have a range of
32 m (120 ft) indoors and 95 m(300 ft) outdoors. The IEE
802.1nhowever, can exceed that
range by more than two times. Range also varies withfrequency
band. Wi-Fi in the 2.4 GHz frequency block hasslightly better range
than Wi-Fi in the 5 GHz frequencyblock. Outdoor ranges - through
use of directional antennas- can be improved with antennas located
several km or
more from their base. In general, the maximum amount ofpower
that a Wi-Fi device can transmit is limited by localregulations
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Mobile use of Wi-Fi over wider ranges islimited, for instance,
to uses such as in anautomobile moving from one hotspot to
another. Other wireless technologies aremore suitable .
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The most common wireless encryption-standard, Wired Equivalent
Privacy orWEP, has been shown to be easily
breakable even when correctly configured.Wi-Fi Protected Access
(WPA and WPA2)encryption, which became available indevices in 2003,
aimed to solve this
problem.
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