Today ‘s vocabulary radio it frequently means connexion without wires or overseas telegrams. This is different to remote control. Wireless Local Area Network ( WLAN ) is the usage of radio devices in a local country web ( LAN ) . LAN is any group of computing machines connected to each other substituting informations in a edifice or campus lab. To accomplish this overseas telegrams are connected from computing machine to routers or switches all through the LAN. With radio, the demands for overseas telegrams are eliminated because electromagnetic moving ridges are used to direct and have informations from computing machines in the web. Besides the 802.11 modem ( term used to mention to WLAN ) is still in its babyhood, high demand, great security hazard, really few experts in the field and may rule the landscape of Network in the hereafter. Wireless Technology may merely render RJ45 overseas telegrams obsolete.
Wireless LAN – WLAN history
This engineering has existed since the 1970ss. Harmonizing to Wikipedia.Org ” In1970 University of Hawaii, under the leading of Norman Abramson, developed the universe ‘s first computing machine communicating web utilizing low-priced ham-like wirelesss, named ALOHAnet ” ( wiki )
In 1979, F.R. Gfeller and U. Bapst published a paper about an experimental radio local country web utilizing diffused infrared communications. Then in 1980, P. Ferrert reported on an experimental application of a individual codification spread spectrum wireless for wireless terminal communications in the IEEE National Telecommunications Conference.
In 1984, Kaveh Pahlavan published a paper in the IEEE Computer Networking Symposium and Communication Society Magazine comparison Infrared and CDMA spread spectrum communications for wireless office information
In 1980 amateur groups developed the first coevals radio informations modems. This was achieved by adding voice-band informations to communication modem and linking it to distance wireless system such as a walky-talky.
Today WLANs are found installed in campuses, airdromes, public topographic points and java stores. The low costs of WLAN equipment has made it low-cost for place usage. New York City has even begun to cover the full metropolis with wireless cyberspace. ( wikipedia )
Both Japan and Korea are get downing to turn over out speedy WiMAX information webs that can present wireless broadband entree to full metropoliss ( www.businessweek.com )
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54 MBit/s WLAN PCI Card ( 802.11g )
WLAN hardware were expensive in the early yearss that it was merely used in topographic points where cabling was hard or impossible to link.
Distance records ( utilizing non-standard devices ) include 382 kilometers ( 237 myocardial infarction ) in June 2007, held by Ermanno Pietrosemoli and EsLaRed of Venezuela, reassigning about 3 MB of informations between the mountain-tops of El Aguila and Platillon. [ Wikipedia ] The Swedish Space Agency transferred informations 420 kilometer ( 260 myocardial infarction ) , utilizing 6 watt amplifiers to make an overhead stratospheric balloon. [ wikipedia.org/wiki/Wi-Fi ]
The image show OSI mention theoretical account for 802.11. The information nexus bed, lower beds of the OSI mention theoretical account is what differentiates it from conventional overseas telegram webs OSI theoretical accounts.
WI-FI is a hallmark name to trade name devices compliant to IEEE 802.11 criterions. Devicess in a WLAN basically use WI-FI branded merchandises. A WI-FI ready device merely means that it is ready for web operation within a WLAN. ( Wikipedia )
Wireless LAN Requirements:
A basic for Wireless local area network:
Ability to cover short distances.
Full connectivity among affiliated Stationss ( NIC )
The 2 chief constituents are
Access point ( A.P )
Wireless station refers to laptops or computing machines with Network Interface Card ( NIC ) . NIC uses wireless signals to pass on, sometimes called wireless arrangers. It contains radio transceivers and logic interacts with client machine and package.
A.P a stationary device which is a portion of wired LAN. Acts as a span between wired webs. Its bridging map is able to link 2 or more webs.
Wireless Networking is accomplished by Sending and having wireless moving ridges between sender and receiving system.
Common footings in wireless transmittal:
Data Rate: Measured in HZ. Faster frequence means more information can be transmitted
Signal Strength: Measured in Watt. WLAN devices by and large transmit 30milliwatts
Antenna: Turns the electrical urges to radio moving ridges.
Range in office infinite: 29 METRES-11Mbps.
Open Area: 485 METRES-1Mbps.
See image below:
Picture shows scope of signal [ 3 ]
There are 2 engineerings chiefly used:
Narrow set engineering uses wireless system to convey and have user information on a specific wireless frequence. Narrowband keeps radio signal frequence every bit narrow as possible to go through signals. This is to avoid unwanted XT. This is achieved by carefully organizing different users on different channel frequences.
Spread spectrum is a transition technique which spreads informations transmittal along the frequence set. This enables users to portion the same frequence set with small intervention from other users. Spread spectrum was used by the armed forces because the wideband signals are difficult to observe and be jammed by enemies. Transmission is more unafraid, dependable and noticeable.
The 2 architecture types for Wireless local area network:
A Ad hoc manner:
Ad-hoc refers to web that connects devices straight with each other. There is no cardinal A.P. It wo n’t pass on with Infrastructure devices or any other devices connected to a wired web. Ad-hoc mode security is less secured than Infrastructure manner web.
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A It is used to link devices which are in the same country. All client Stationss are grouped together in a individual geographic country.
Infrastructure manner requires an Access Point like 802.11 WLAN routers. Benefit of Infrastructure manner is increased degrees of security, potentially faster informations transmittal velocities and integrating with a wired web supplying radio coverage to edifices or university country. Each client Stationss or computing machine must hold NIC installed to link to the web.
hypertext transfer protocol: //welcome.solutions.brother.com/BSC/FAQ_IKOU_IMG/faq000447_000/Infrastructure.gif
IEEE Wireless Networking Specifications
The IEEE refers to Institute of Electrical and Electronic Engineers which provides a planetary criterion for the 802.11. This is to enable WLAN devices of different makers to be able to link and hold the same specification and work together interchangeably. It foremost released the 802.11 specifications in June 1999. The first specification for 802.11 had 2.4 GHz frequence with 1 Mbps. The latest specification is the 802.11g which supports 54 Mbps and 60 Mbps
802.11 operated in the 2.4 GHz scope and was the original specification of the 802.11 IEEE criterions. This specification delivered 1 to 2 Mbps utilizing a engineering known as phase-shift keying ( PSK ) transition. This specification is no longer used and has mostly been replaced by other signifiers of the 802.11 criterion. [ 5 ]
802.11a operates in the 5 – 6 GHz scope with informations rates normally in the 6 Mbps, 12 Mbps, or 24 Mbps scope. Because 802.11a uses the extraneous frequence division multiplexing
( OFDM ) criterion, informations transfer rates can be every bit high as 54 Mbps. OFDM breaks up fast consecutive information signals into several slower sub-signals that are transferred at the same clip via different frequences, supplying more opposition to radio frequence intervention. The
802.11a specification is besides known as Wi-Fi5, and though regionally deployed, it is non a planetary criterion like 802.11b. [ 5 ]
2.4 GHz scope with up to 600 Mbps informations set to let go of in 2012.
WLAN has a weak security policy. It fundamentally uses 3 basic security services:
Authentication: Checking the individuality
Integrity: Ensures the message that it is non modified.
Privacy: Preventing inactive onslaughts.
Harmonizing to website wikipedia ” Anyone within the geographical web scope of an unfastened, unencrypted radio web can ‘sniff ‘ or enter the traffic, addition unauthorised entree to internal web resources every bit good as to the cyberspace, and so perchance direct Spam or make other illegal actions utilizing the radio web ‘s IP reference, all of which are rare for place routers but may be important concerns for office webs ‘ . [ 6 ]
Piggybacking refers to entree to a wireless Internet connexion by conveying one ‘s ain computing machine within the scope of another ‘s wireless connexion, and utilizing that service without the endorser ‘s expressed permission or cognition. [ 6 ]
‘Sniff ‘ or ‘spoofing ‘ as its sometimes called, session highjacking is accomplished by supervising a valid radio station successfully complete authenticating to the web with a protocol cubic decimeter analyzer. The aggressor will direct a spoofed disassociate message from the AP doing the radio station to unplug.
When WEP ( Wired Equivalent Privacy ) is non activated by place or office user, the aggressor has usage of the connexion until the following clip out. The wireless station and AP are non synchronized leting the aggressor to dissociate the radio station while the AP is incognizant that the original radio station is non connected. [ 6 ]
The increasing usage of Wireless LANs has created over looked exposures that allow choping. Schemes that have worked on procuring wired webs should be implemented on WLAN and its exposures.
Benefits of Wireless local area network:
The general benefits of WLAN are: Mobility:
Information can be accessed from any where in the campus
put ining a Wireless LAN is speedy and easy.
No wiring except in Access Point Installlation
Easily upgradeable and low cost to proprietor
installing cost is less compared to Wired LAN
Scalability, Can connect over 1000 users
Classroomsoffice and other can hold flexible entree to the web, more infinite
Warehouse workers can interchange information with cardinal databases and increase their productiveness
11 Mbps for 802.11b
54 Mbps for 802.11a/g ( GSM:9.6Kbps, HCSCD: ~40Kbps, GPRS: ~160Kbps, WCDMA: up to 2Mbps )
Long-run cost nest eggs
O & A ; M cheaper that for wired cyberspaces
Semens from easy care, telegraphing cost, working efficiency and truth
Network can be established in a new location merely by traveling the Personal computers!
Because WLAN is still by and large new in comparing to wired LAN, there has non been much attending given to bettering overall quality and tweaking its bugs. Range and coverage depends on the transmittal power and having capablenesss of the transceiver. Radio intervention can do debasement in end product. Any intervention caused by lakes or walls. If the figure of clients increased for a peculiar entree point, public presentation will diminish and do internet slowdown.
Wireless engineerings will go a lasting fixture concern and places throughout the universe. WLAN outperforms conventional LAN, besides physically easy to upgrade. Initially WLAN was outputting at 2 Mbps so WLAN has reached velocity up to 100Mbps and shortly Wi-Fi in Korea will transcend 1Gbps by 2012on the new 802.11n. [ 4 ] Any imaginable impression that WLAN will replace conventional LAN is extremely improbable, overall. Long distance communicating still needs overseas telegrams so do telephone lines. But for little countries, like schoolroom, office and places WLAN proves to be the best violable option both in practicality and comfort.
[ 1 ] hypertext transfer protocol: //www.businessweek.com/magazine/content/06_49/b4012071.htm
[ 2 ] www.campusmiles.com/tech… /presentation20.html
[ 3 ] hypertext transfer protocol: //www.scribd.com/doc/38121269/WLAN-Seminar-Report
[ 4 ] hypertext transfer protocol: //www.htlounge.net/art/10047/wi-fi-expected-to-exceed-1gbps-by-2012.html
[ 5 ] hypertext transfer protocol: //en.wikipedia.org/wiki/Wireless_LAN
[ 6 ] hypertext transfer protocol: //en.wikipedia.org/wiki/Wireless_LAN_security