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Total Number of Subscribers: 464 |
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Date:26th September 2008 |
Compiled by Mr. M. Sathya Kumar |
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Wi - Fi Wi-Fi is the trade name for the popular
wireless technology used in home networks, mobile phones, video games and
more. In particular, it covers the various IEEE 802.11 technologies .Wi-Fi
technologies are supported by nearly every modern personal computer operating
system and most advanced game consoles, printers, and other peripherals. Purpose The purpose of Wi-Fi is to hide complexity
by enabling wireless access to applications and data, media and streams. The
main aims of Wi-Fi are the following: make access to information easier ensure compatibility and co-existence of
devices eliminate cabling and wiring eliminate switches, adapters, plugs, pins
and connectors. Uses A Wi-Fi enabled device such as a PC, game console, mobile phone,
MP3 player or PDA can connect to the Internet when within range of a wireless
network connected to the Internet. The coverage of one or more interconnected
access points — called a hotspot — can comprise an area as small as a single room with wireless-opaque
walls or as large as many square miles covered by overlapping access points.
Wi-Fi technology has served to set up mesh networks, for example, in
London.[1] Both architectures can operate in community networks. In addition to restricted use in homes and offices, Wi-Fi can
make access publicly available at Wi-Fi hotspots provided either free of
charge or to subscribers to various providers. Organizations and businesses
such as airports, hotels and restaurants often provide free hotspots to
attract or assist clients. Enthusiasts or authorities who wish to provide
services or even to promote business in a given area sometimes provide free
Wi-Fi access. Metropolitan-wide Wi-Fi (Muni-Fi) already has more than 300
projects in process.There were 879 Wi-Fi based Wireless Internet service
providers in the Czech Republic as of May 2008. 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 can prove useful in consumer electronics and gaming
applications. When wireless networking technology first entered the market
many problems ensued for consumers who could not rely on products from
different vendors working together. The Wi-Fi Alliance began as a community
to solve this issue — aiming to address the needs
of the end-user and to allow the technology to mature. The Alliance created
the branding Wi-Fi CERTIFIED to reassure consumers that products will
interoperate 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-modem or a cable-modem and a
Wi-Fi access point, often set up in homes and other premises, provide
Internet-access and internetworking to all devices connected (wirelessly or
by cable) to them. One can also connect Wi-Fi devices in ad-hoc mode for
client-to-client connections without a router. As of 2007 Wi-Fi technology had spread widely within business
and industrial sites. In business environments, just like other 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
by defining 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 the
role of mere "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. Advantages and challenges Operational advantages Wi-Fi allows LANs (Local Area Networks) 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. In 2008, 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 even more devices. Wi-Fi has become
widespread in corporate infrastructures. 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
compatible. 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 220,000 public hotspots
and tens of millions of homes and corporate and university campuses worldwide.[5]
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. Reach Due to reach requirements for wireless LAN applications, power
consumption is fairly high compared to some other low-bandwidth standards.
Especially Zigbee and Bluetooth supporting wireless PAN applications refer to
much lesser propagation range of <10m (ref. e.g. IEEE Std. 802.15.4
section 1.2 scope). Range is always making battery life a concern. 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 performance decreases roughly quadratically as the range
increases at constant radiation levels. Mobility Because of the very limited practical range of Wi-Fi, mobile use
is essentially confined to such applications as inventory taking machines in
warehouses or retail spaces, barcode reading devices at check-out stands or
receiving / shipping stations. Mobile use of Wi-Fi over wider ranges is
limited to move, use, move, as for instance in an automobile moving from one
hotspot to another. Threats to security 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 any wireless 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 Source
: The Technology. com |
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