Wi-fi

Wi-fi is a popular technology that allows an electronic device to exchange datawirelesslyover acomputer network, including high-speedInternetconnections. TheWi-Fi Alliancedefines Wi-Fi as any "wireless local area network(WLAN) products that are based on theInstitute of Electrical and Electronics Engineers' (IEEE) 802.11 standards".However, since most modern WLANs are based on these standards, the term "Wi-Fi" is used in general English as a synonym for "WLAN".

A device that can use Wi-Fican connect to a network resource such as the Internet via awireless network access point. Such an access point (orhotspot) has a range of about 20 meters (65feet) indoors and a greater range outdoors. Hotspot coverage can comprise an area as small as a single room with walls that block radio waves or as large as many square miles — this is achieved by using multiple overlapping access points.

The nameWi-Fi

The termWi-Fi, first used commercially in August 1999,was coined by a brand-consulting firm calledInterbrandCorporation that the Alliance had hired to determine a name that was "a little catchier than 'IEEE 802.11b Direct Sequence'".Belanger also stated that Interbrand inventedWi-Fias aplay on wordswithHi-Fi, and also created the Wi-Fi logo.

The Wi-Fi Alliance initially used anadvertising sloganfor Wi-Fi, "The Standard for Wireless Fidelity",but later removed the phrase from their marketing. Despite this, some documents from the Alliance dated 2003 and 2004 still contain the termWireless Fidelity.There was no official statement related to the dropping of the term.

Theyin-yangWi-Fi logo indicates the certification of a product forinteroperability.

Non-Wi-Fi technologies intended for fixed points such asMotorola Canopyare usually described asfixed wireless. Alternative wireless technologies include mobile phone standards such as2G,3Gor4G.

To connect to a Wi-Fi LAN, a computer has to be equipped with awireless network interface controller. The combination of computer and interface controller is called astation. All stations share a single radio frequency communication channel. Transmissions on this channel are received by all stations within range. The hardware does not signal the user that the transmission was delivered and is therefore called abest-effort deliverymechanism. A carrier wave is used to transmit the data in packets, referred to as "Ethernet frames". Each station is constantly tuned in on the radio frequency communication channel to pick up available transmissions.

The wi-fi signal loop

Internet access

A Wi-Fi-enabled device can connect to the Internet when within range of awireless networkconnected to the Internet. The coverage of one or more (interconnected)access points— called hotspots — can extend from an area as small as a few rooms to as large as many square miles. Coverage in the larger area may require a group of access points with overlapping coverage. Outdoor public Wi-Fi technology has been used successfully inwireless mesh networksin London, UK.

Wi-Fi provides service in private homes, high street chains and independent businesses, as well as in public spaces at Wi-Fi hotspots set up either free-of-charge or commercially. Organizations andbusinesses, such as airports, hotels, and restaurants, often provide free-use hotspots to attract customers. Enthusiasts or authorities who wish to provide services or even to promote business in selected areas sometimes provide free Wi-Fi access.

Routersthat incorporate adigital subscriber linemodem or acable modemand a Wi-Fi access point, often set up in homes and other buildings, provide Internet access andinternetworkingto all devices connected to them, wirelessly or via cable. With the emergence ofMiFiandWiBro(a portable Wi-Fi router) people can easily create their own Wi-Fi hotspots that connect to Internet viacellular networks. NowAndroid,Bada,iOS(iPhone), andSymbiandevices can create wireless connections.Wi-Fi also connects places that normally don't have network access, such as kitchens and garden sheds.

Wi-Fi networks have limited range. A typical wireless access point using802.11bor802.11gwith a stock antenna might have a range of 32m (120ft) indoors and 95m (300ft) outdoors.IEEE 802.11n, however, can more than double the range.Range also varies with frequency band. Wi-Fi in the 2.4GHz frequency block has slightly better range than Wi-Fi in the 5GHz frequency block which is used by 802.11a. On wireless routers with detachable antennas, it is possible to improve range by fitting upgraded antennas which have higher gain in particular directions. Outdoor ranges can be improved to many kilometers through the use of high gaindirectional antennasat the router and remote device(s). In general, the maximum amount of power that a Wi-Fi device can transmit is limited by local regulations, such asFCC Part 15in the US.

Due to reach requirements for wireless LAN applications, Wi-Fi has fairly high power consumption compared to some other standards. Technologies such asBluetooth(designed to support wirelessPANapplications) provide a much shorterpropagationrange of <10mand so in general have a lower power consumption. Other low-power technologies such asZigBeehave fairly long range, but much lower data rate. The high power consumption of Wi-Fi makes battery life in mobile devices a concern.

Researchers have developed a number of "no new wires" technologies to provide alternatives to Wi-Fi for applications in which Wi-Fi's indoor range is not adequate and where installing new wires (such asCAT-5) is not possible or cost-effective. For example, theITU-TG.hnstandard for high speedLocal area networksuses existing home wiring (coaxial cables, phone lines andpower lines). AlthoughG.hndoes not provide some of the advantages of Wi-Fi (such as mobility or outdoor use), it's designed for applications (such asIPTVdistribution) where indoor range is more important than mobility.

Due to the complex nature ofradio propagationat typical Wi-Fi frequencies, particularly the effects of signal reflection off trees and buildings, algorithms can only approximately predict Wi-Fi signal strength for any given area in relation to a transmitter.This effect does not apply equally tolong-range Wi-Fi, since longer links typically operate from towers that transmit above the surrounding foliage.

The practical range of Wi-Fi essentially confines mobile use to such applications as inventory-taking machines in warehouses or in retail spaces,barcode-reading devices at check-out stands, or receiving/shipping stations. Mobile use of Wi-Fi over wider ranges is limited, for instance, to uses such as in an automobile moving from one hotspot to another. Other wireless technologies are more suitable for communicating with moving vehicles

To setup a wireless network-

It’s handy, simple and relatively cheap to set up a wireless (WiFi) network in your own home. It saves you from having to connect and disconnect all sorts of wires for your computers just in order to hook up to the Internet.

If you want to create your own wireless network at home, you’ll need a wireless access point. If your home computers aren’t networked, or if you want to replace your Ethernet network you’ll need to set up a wireless router. This will enable you to use either wireless radio signals or Ethernet cables to link up your computers to each other, to your printer, and also to the Internet. The 802.11g router is usually recommended as it is fast and reliable.

Once the router is plugged in, it will work according to its default settings. You can alter the settings by accessing a Web interface. Select the name of the network, which is also known as its service set identifier (SSID). Choose a channel. Most people -- probably including your neighbors -- use channel six, which might cause interference on your line, so choose a different channel. Set up a username and password to protect the security of your router; otherwise, anyone nearby with a wireless card in their computer will be able to tap into your signal.

To protect the privacy of your network, you could use the WiFi Protected Access (WPA), which is a new-and-improved version of the once standard Wired Equivalency Privacy (WEP) security program. This is the option most public hotspots use, and it can be accessed by signing in with a password. Alternatively, you could set up a Media Access Control (MAC) address-filtering program, which does not rely on passwords. To do this, you’ll have to set up your router with a list of the specific MAC addresses on your computers.

Advantages-

One of the most prevalent advantages of WiFi wireless LAN technologies is that it is completely wire-free. Now, if you want to sit in one of your comfort zones in you house, such as a couch or in your yard, you can carry your laptop with you and still be able to access the internet.

There are many WiFi advantages to users. Let's have a closer look at them:

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  • WiFi uses unlicensed radio spectrum and does not requireregulatoryapproval forindividualdeployers.

  • It allows local area networks (LANs) to be setup with cabling. The can reduce associated costs ofnetwork connectionand expansions. Places where cables cannot be run, such as outdoor areas and historical buildings can use wireless LANs.
  • WiFi products are extensively available in the market. There are different brands of access points and user's network interfaces are able to inter-operate at a very basic service level.
  • Prices are considerably lower as competition amongst vendors' increases.
  • WiFi networks can support roaming. This allows mobile users with laptop computer to be able to move from one access point to another.

  • Numerous access points and network interfaces support various degrees of encryption to protect traffic from interception.
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  • WiFi has a set of global standards. Not like the cellular carriers, the same WiFi users can work in different countries around the world at all time.

Disadvantages-

Due the fact that WiFi are still relatively new, there are considerably more disadvantages to users. Let's have a look at them:

  • The use of WiFi band that is 2.4 GHz does not require a license in most countries provided that is stays below limit of 100mW and one accepts interference from other sources; including interference which causes the users devices to no longer function.

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  • The spectrum assignments and operational limitations are not consistent worldwide.
  • Power consumption is fairly high compared to some other standards, making the battery life and heat a concern to some users.

  • WiFi uses the unlicensed 2.4GHz spectrum, which often crowded with other devices such as Bluetooth, microwave ovens, cordless phones, or video sender devices, and among many others. This may cause degradation in performance.
  • WiFi networks have limited range. A typical WiFi home router might have a range of 45m (150ft) indoors and 90m (300ft) outdoors. Ranges may also vary as WiFi is no exception to the physics of radio wave propagation with frequency band.
  • The most common wireless encryption standard, wired equivalent privacy or WEP has been shown to be breakable even when it has been correctly configured.
  • Access points could be used to steal personal and confidential information transmitted from WiFi consumers.

  • Intervention of a closed or encrypted access point with other open access points on the same or a nearby channel can prevent access to the open access points by others in the area. It poses a high problem in high-density areas such as large apartment blocks where many residents are operating WiFi access points.
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  • Inter-operability issues between brands or deviations can cause limited connection or lower output speeds.
  • Free access points can be used by the malicious to anonymous to initiate an attack that would be extremely difficult to track beyond the owner of the access point.