Wi-Fi also unofficially known as Wireless Fidelity, is a wireless technology
brand owned by the Wi-Fi Alliance intended to improve the interoperability of
wireless local area network products based on the IEEE 802.11 standards.
Common applications for Wi-Fi include Internet and VoIP phone access, gaming,
and network connectivity for consumer electronics such as televisions, DVD
players, and digital cameras.
Definition Wi-Fi Alliance is a consortium of separate and independent companies
agreeing to a set of common interoperable products based on the family
of IEEE 802.11 standards. Wi-Fi certifies products via a set of established test
procedures to establish interoperability. Those manufacturers that are members
of Wi-Fi Alliance whose products pass these interoperability tests can mark
their products and product packaging with the Wi-Fi logo.
Products which successfully pass the Wi-Fi Alliance testing may use the Wi-Fi
CERTIFIED brand. The Alliance tests and certifies the interoperability of wireless LAN
products based on the IEEE 802.11 standards. Studies show that 88% of consumers
prefer products that have been tested by an independent organization.
Wi-Fi technologies have gone through several generations since their inception
in 1997. Wi-Fi is supported to different extents under Microsoft Windows, Apple
Macintosh and open source Unix and Linux operating systems. Contrary to popular
belief, Wi-Fi is not an abbreviation for "Wireless Fidelity" (see "Origin and
meaning of the term "Wi-Fi" below).
Uses A Wi-Fi enabled device such as a PC, game console, cell phone, MP3
player or PDA can connect to the Internet when within range of a wireless
network connected to the Internet. The area covered by one or more
interconnected access points is called a hotspot. Hotspots can cover as little
as a single room with wireless-opaque walls or as much as many square miles
covered by overlapping access points. Wi-Fi can also be used to create a mesh
network. Both architectures are used in community networks.[citation needed]
Wi-Fi also allows connectivity in peer-to-peer (wireless ad-hoc network) mode,
which enables devices to connect directly with each other. This connectivity
mode is useful in consumer electronics and gaming applications.
When the technology was first commercialized there were many problems because
consumers could not be sure that products from different vendors would work
together. The Wi-Fi Alliance began as a community to solve this issue so as to
address the needs of the end user and allow the technology to mature. The
Alliance created the branding Wi-Fi CERTIFIED to show consumers that products
are interoperable with other products displaying the same branding.
Many consumer devices use Wi-Fi. Amongst others, personal computers can network
to each other and connect to the Internet, mobile computers can connect to the
Internet from any Wi-Fi hotspot, and digital cameras can transfer images
wirelessly.
Routers which incorporate a DSL or cable modem and a Wi-Fi access point are
often used in homes and other premises, and provide Internet access and
internetworking to all devices connected wirelessly or by cable into them.
Devices supporting Wi-Fi can also be connected in ad-hoc mode for
client-to-client connections without a router.
Business and industrial Wi-Fi is widespread as of 2007. In business environments,
increasing the number of Wi-Fi access points provides redundancy, support for fast
roaming and increased overall network capacity by using more channels or creating
smaller cells. Wi-Fi enables wireless voice applications (VoWLAN or WVOIP). Over
the years, Wi-Fi implementations have moved toward 'thin' access points, with more
of the network intelligence housed in a centralized network appliance, relegating
individual Access Points to be simply 'dumb' radios. Outdoor applications may utilize
true mesh topologies. As of 2007 Wi-Fi installations can provide a secure computer
networking gateway, firewall, DHCP server, intrusion detection system, and other
functions.
In addition to restricted use in homes and offices, Wi-Fi is publicly available
at Wi-Fi hotspots provided either free of charge or to subscribers to various
providers. Free hotspots are often provided by businesses such as hotels,
restaurants, and airports who offer the service to attract or assist clients.
Sometimes free Wi-Fi is provided by enthusiasts, or by organizations or
authorities who wish to promote business in their area. Metropolitan-wide WiFi
(Mu-Fi) already has more than 300 projects in process.
Advantages of Wi-Fi Wi-Fi allows LANs to be deployed without cabling for
client devices, typically reducing the costs of network deployment and
expansion. Spaces where cables cannot be run, such as outdoor areas and
historical buildings, can host wireless LANs.
As of 2007 wireless network adapters are built into most modern laptops. The
price of chipsets for Wi-Fi continues to drop, making it an economical
networking option included in ever more devices. Wi-Fi has become widespread in
corporate infrastructures, which also helps with the deployment of RFID
technology that can piggyback on Wi-Fi.
Different competitive brands of access points and client network interfaces are
inter-operable at a basic level of service. Products designated as "Wi-Fi
Certified" by the Wi-Fi Alliance are backwards inter-operable. Wi-Fi is a
global set of standards. Unlike mobile telephones, any standard Wi-Fi device
will work anywhere in the world.
Wi-Fi is widely available in more than 250,000 public hotspots and tens of
millions of homes and corporate and university campuses worldwide. WPA is not
easily cracked if strong passwords are used and WPA2 encryption has no known
weaknesses. New protocols for Quality of Service (WMM) make Wi-Fi more suitable
for latency-sensitive applications (such as voice and video), and power saving
mechanisms (WMM Power Save) improve battery operation.
Disadvantages of Wi-Fi Spectrum assignments and operational limitations
are not consistent worldwide. Most of Europe allows for an additional 2 channels
beyond those permitted in the U.S for the 2.4 GHz band. (1-13 vs. 1-11); Japan
has one more on top of that (1-14). Europe, as of 2007, is now essentially
homogeneous in this respect. A very confusing aspect is the fact a WiFI signal
actually occupies five channels in the 2.4 GHz resulting in only 3
non-overlapped channels in the US: 1, 6, 11, and four in Europe: 1,5,9,13
Some countries, such as Italy, formerly required a 'general authorization' for
any Wi-Fi used outside an operator's own premises, or require something akin to
an operator registration.[citation needed] Equivalent isotropically radiated
power (EIRP) in the EU is limited to 20 dBm (0.1 W).
Power consumption is fairly high compared to some other low-bandwidth standards,
such as Zigbee and Bluetooth, making battery life a concern.
The most common wireless encryption standard, Wired Equivalent Privacy or WEP,
has been shown to be easily breakable even when correctly configured. Wi-Fi
Protected Access (WPA and WPA2), which began shipping in 2003, aims to solve
this problem and is now available on most products. Wi-Fi Access Points
typically default to an open (encryption-free) mode. Novice users benefit from a
zero-configuration device that works out of the box, but this default is without
security enabled, providing open wireless access to their LAN. To turn security
on requires the user to configure the device, usually via a software graphical
user interface (GUI). Wi-Fi networks that are open (unencrypted) can be
monitored and used to read and copy data (including personal information)
transmitted over the network, unless another security method is used to secure
the data, such as a VPN or a secure web page. (See HTTPS/Secure Socket Layer.)
Many 2.4 GHz 802.11b and 802.11g Access points default to the same channel on
initial startup, contributing to congestion on certain channels. To change the
channel of operation for an access point requires the user to configure the
device.
Wi-Fi networks have limited range. A typical Wi-Fi home router using 802.11b or
802.11g with a stock antenna might have a range of 32 m (120 ft) indoors and 95
m (300 ft) outdoors. Range also varies with frequency band. Wi-Fi in the 2.4 GHz
frequency block has slightly better range than Wi-Fi in the 5 GHz frequency
block. Outdoor range with improved (directional) antennas can be several
kilometres or more with line-of-sight.
Wi-Fi pollution, or an excessive number of access points in the area, especially
on the same or neighboring channel, can prevent access and interfere with the
use of other access points by others, caused by overlapping channels in the
802.11g/b spectrum, as well as with decreased signal-to-noise ratio (SNR)
between access points. This can be a problem in high-density areas, such as
large apartment complexes or office buildings with many Wi-Fi access points.
Additionally, other devices use the 2.4 GHz band: microwave ovens, security
cameras, Bluetooth devices and (in some countries) Amateur radio, videosenders,
cordless phones and baby monitors can cause significant additional interference.
General guidance to those who suffer these forms of interference or network
crowding is to migrate to a WiFi 5GHz product (802.11a) usually a dual band
product as the 5GHz band is relatively unused and there are many more channels
available. This also requires users to set up the 5GHz band to be the preferred
network in the client and to configure each network band to a different
name(SSID).
It is also an issue when municipalities, or other large entities such as
universities, seek to provide large area coverage. Everyone is considered equal
for the base standard without 802.11e/WMM when they use the band. This openness
is also important to the success and widespread use of 2.4 GHz Wi-Fi, but makes
it unsuitable for "must-have" public service functions or where reliability is
required.
Interoperability issues between brands or proprietary deviations from the
standard can disrupt connections or lower throughput speeds on other user's
devices that are within range.
Attributes and Credits-The information and facts supplied on this subject
derive from http://en.wikipedia.org/wiki/Main_Page
brand owned by the Wi-Fi Alliance intended to improve the interoperability of
wireless local area network products based on the IEEE 802.11 standards.
Common applications for Wi-Fi include Internet and VoIP phone access, gaming,
and network connectivity for consumer electronics such as televisions, DVD
players, and digital cameras.
Definition Wi-Fi Alliance is a consortium of separate and independent companies
agreeing to a set of common interoperable products based on the family
of IEEE 802.11 standards. Wi-Fi certifies products via a set of established test
procedures to establish interoperability. Those manufacturers that are members
of Wi-Fi Alliance whose products pass these interoperability tests can mark
their products and product packaging with the Wi-Fi logo.
Products which successfully pass the Wi-Fi Alliance testing may use the Wi-Fi
CERTIFIED brand. The Alliance tests and certifies the interoperability of wireless LAN
products based on the IEEE 802.11 standards. Studies show that 88% of consumers
prefer products that have been tested by an independent organization.
Wi-Fi technologies have gone through several generations since their inception
in 1997. Wi-Fi is supported to different extents under Microsoft Windows, Apple
Macintosh and open source Unix and Linux operating systems. Contrary to popular
belief, Wi-Fi is not an abbreviation for "Wireless Fidelity" (see "Origin and
meaning of the term "Wi-Fi" below).
Uses A Wi-Fi enabled device such as a PC, game console, cell phone, MP3
player or PDA can connect to the Internet when within range of a wireless
network connected to the Internet. The area covered by one or more
interconnected access points is called a hotspot. Hotspots can cover as little
as a single room with wireless-opaque walls or as much as many square miles
covered by overlapping access points. Wi-Fi can also be used to create a mesh
network. Both architectures are used in community networks.[citation needed]
Wi-Fi also allows connectivity in peer-to-peer (wireless ad-hoc network) mode,
which enables devices to connect directly with each other. This connectivity
mode is useful in consumer electronics and gaming applications.
When the technology was first commercialized there were many problems because
consumers could not be sure that products from different vendors would work
together. The Wi-Fi Alliance began as a community to solve this issue so as to
address the needs of the end user and allow the technology to mature. The
Alliance created the branding Wi-Fi CERTIFIED to show consumers that products
are interoperable with other products displaying the same branding.
Many consumer devices use Wi-Fi. Amongst others, personal computers can network
to each other and connect to the Internet, mobile computers can connect to the
Internet from any Wi-Fi hotspot, and digital cameras can transfer images
wirelessly.
Routers which incorporate a DSL or cable modem and a Wi-Fi access point are
often used in homes and other premises, and provide Internet access and
internetworking to all devices connected wirelessly or by cable into them.
Devices supporting Wi-Fi can also be connected in ad-hoc mode for
client-to-client connections without a router.
Business and industrial Wi-Fi is widespread as of 2007. In business environments,
increasing the number of Wi-Fi access points provides redundancy, support for fast
roaming and increased overall network capacity by using more channels or creating
smaller cells. Wi-Fi enables wireless voice applications (VoWLAN or WVOIP). Over
the years, Wi-Fi implementations have moved toward 'thin' access points, with more
of the network intelligence housed in a centralized network appliance, relegating
individual Access Points to be simply 'dumb' radios. Outdoor applications may utilize
true mesh topologies. As of 2007 Wi-Fi installations can provide a secure computer
networking gateway, firewall, DHCP server, intrusion detection system, and other
functions.
In addition to restricted use in homes and offices, Wi-Fi is publicly available
at Wi-Fi hotspots provided either free of charge or to subscribers to various
providers. Free hotspots are often provided by businesses such as hotels,
restaurants, and airports who offer the service to attract or assist clients.
Sometimes free Wi-Fi is provided by enthusiasts, or by organizations or
authorities who wish to promote business in their area. Metropolitan-wide WiFi
(Mu-Fi) already has more than 300 projects in process.
Advantages of Wi-Fi Wi-Fi allows LANs to be deployed without cabling for
client devices, typically reducing the costs of network deployment and
expansion. Spaces where cables cannot be run, such as outdoor areas and
historical buildings, can host wireless LANs.
As of 2007 wireless network adapters are built into most modern laptops. The
price of chipsets for Wi-Fi continues to drop, making it an economical
networking option included in ever more devices. Wi-Fi has become widespread in
corporate infrastructures, which also helps with the deployment of RFID
technology that can piggyback on Wi-Fi.
Different competitive brands of access points and client network interfaces are
inter-operable at a basic level of service. Products designated as "Wi-Fi
Certified" by the Wi-Fi Alliance are backwards inter-operable. Wi-Fi is a
global set of standards. Unlike mobile telephones, any standard Wi-Fi device
will work anywhere in the world.
Wi-Fi is widely available in more than 250,000 public hotspots and tens of
millions of homes and corporate and university campuses worldwide. WPA is not
easily cracked if strong passwords are used and WPA2 encryption has no known
weaknesses. New protocols for Quality of Service (WMM) make Wi-Fi more suitable
for latency-sensitive applications (such as voice and video), and power saving
mechanisms (WMM Power Save) improve battery operation.
Disadvantages of Wi-Fi Spectrum assignments and operational limitations
are not consistent worldwide. Most of Europe allows for an additional 2 channels
beyond those permitted in the U.S for the 2.4 GHz band. (1-13 vs. 1-11); Japan
has one more on top of that (1-14). Europe, as of 2007, is now essentially
homogeneous in this respect. A very confusing aspect is the fact a WiFI signal
actually occupies five channels in the 2.4 GHz resulting in only 3
non-overlapped channels in the US: 1, 6, 11, and four in Europe: 1,5,9,13
Some countries, such as Italy, formerly required a 'general authorization' for
any Wi-Fi used outside an operator's own premises, or require something akin to
an operator registration.[citation needed] Equivalent isotropically radiated
power (EIRP) in the EU is limited to 20 dBm (0.1 W).
Power consumption is fairly high compared to some other low-bandwidth standards,
such as Zigbee and Bluetooth, making battery life a concern.
The most common wireless encryption standard, Wired Equivalent Privacy or WEP,
has been shown to be easily breakable even when correctly configured. Wi-Fi
Protected Access (WPA and WPA2), which began shipping in 2003, aims to solve
this problem and is now available on most products. Wi-Fi Access Points
typically default to an open (encryption-free) mode. Novice users benefit from a
zero-configuration device that works out of the box, but this default is without
security enabled, providing open wireless access to their LAN. To turn security
on requires the user to configure the device, usually via a software graphical
user interface (GUI). Wi-Fi networks that are open (unencrypted) can be
monitored and used to read and copy data (including personal information)
transmitted over the network, unless another security method is used to secure
the data, such as a VPN or a secure web page. (See HTTPS/Secure Socket Layer.)
Many 2.4 GHz 802.11b and 802.11g Access points default to the same channel on
initial startup, contributing to congestion on certain channels. To change the
channel of operation for an access point requires the user to configure the
device.
Wi-Fi networks have limited range. A typical Wi-Fi home router using 802.11b or
802.11g with a stock antenna might have a range of 32 m (120 ft) indoors and 95
m (300 ft) outdoors. Range also varies with frequency band. Wi-Fi in the 2.4 GHz
frequency block has slightly better range than Wi-Fi in the 5 GHz frequency
block. Outdoor range with improved (directional) antennas can be several
kilometres or more with line-of-sight.
Wi-Fi pollution, or an excessive number of access points in the area, especially
on the same or neighboring channel, can prevent access and interfere with the
use of other access points by others, caused by overlapping channels in the
802.11g/b spectrum, as well as with decreased signal-to-noise ratio (SNR)
between access points. This can be a problem in high-density areas, such as
large apartment complexes or office buildings with many Wi-Fi access points.
Additionally, other devices use the 2.4 GHz band: microwave ovens, security
cameras, Bluetooth devices and (in some countries) Amateur radio, videosenders,
cordless phones and baby monitors can cause significant additional interference.
General guidance to those who suffer these forms of interference or network
crowding is to migrate to a WiFi 5GHz product (802.11a) usually a dual band
product as the 5GHz band is relatively unused and there are many more channels
available. This also requires users to set up the 5GHz band to be the preferred
network in the client and to configure each network band to a different
name(SSID).
It is also an issue when municipalities, or other large entities such as
universities, seek to provide large area coverage. Everyone is considered equal
for the base standard without 802.11e/WMM when they use the band. This openness
is also important to the success and widespread use of 2.4 GHz Wi-Fi, but makes
it unsuitable for "must-have" public service functions or where reliability is
required.
Interoperability issues between brands or proprietary deviations from the
standard can disrupt connections or lower throughput speeds on other user's
devices that are within range.
Attributes and Credits-The information and facts supplied on this subject
derive from http://en.wikipedia.org/wiki/Main_Page
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