Monday, July 22, 2019

WLAN

A Wireless Local Area NetworkWLAN) Is A Wireless Computer Network That Links Two Or More Devices(Computers) Using Wireless Distribution Method.Within A Limited Area Such As School,Home,Computer Laboratory,Collage Building,Office Building.

WiFi Is A Wireless LAN (WLAN),WiFi Operation Uses The Carrier Sense Multiple Access With Collision Avoidance Method.

Observe The Below Picture.

There Are Four Computers And One Wireless Access point (Router).

If Computer 1 Wants To Send Data Frame To Computer 4 It First Listens Or Senses The Media To Be Sure Its Free.

And If The Media Is Busy The Computer 1 Must Wait.

 

If The Media Is Free Computer 1 Sends The Data Frame To Computer 4.

The Wireless Access Point (Router)Receives The Message And In A Similar Manner To A Hub,Repeats It.

 

Computer 4 Receives The Data Frame When Computer 2,3 Discards It.

Computer 4 Then Sends A Acknowledgement Frame Back To Computer 1 To Verify The Frame Was Received Successfully.

 

An Advanced Operational Wifi Mode Uses Handshaking.

This Mode Usually Only Supported By High End Wifi NICs And Is Used When Stations Are Located Far Apart, Causing The Hidden Node Problem.

 

 

In This Mode Computer 1 Again Must First Listen To Verify The Media Is Not In Use.

 

If The Media Is Free, Computer 1 Must In A Sense,Ask Permission To Transmit Bys Sending A Request To Send (RTS) Message To The Access Point.

The Access Point Replies With A Clear To Send (CTS) Message If The Media Remains Free.

The CTS Message Is Heard By All Other Computer Stations Notifying That Another Station Is About To Transmit And Then They Must Wait Before Attempting To Transmit.

The Amount Of Time To Wait Is A Part Of CTS Message.

 

Computer 1 Now Sends Data Frame To Computer 4.

Computer 4 Receives The Data Frame And Then Sends Acknowledge Frame Back To Computer 1.

 

This Is The Operation In WLAN(Wireless LAN).

I Hope You Understood.

 

 

 

 

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