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Wireless Fidelity ( Wi-Fi ). Submitted by, Premsingh Thangasamy.S 9911112007 I year M.Tech Network Engineering. Agenda. Introduction How Wi-Fi Works? Wi-Fi Technology How to connect Wi-Fi Network? Wi-Fi Access Protocol

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Wireless Fidelity ( Wi-Fi )

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Wireless fidelity wi fi

Wireless Fidelity(Wi-Fi)

Submitted by,

Premsingh Thangasamy.S


I year M.Tech

Network Engineering

Wireless fidelity wi fi


  • Introduction

  • How Wi-Fi Works?

  • Wi-Fi Technology

  • How to connect Wi-Fi Network?

  • Wi-Fi Access Protocol

  • Wi-Fi Applications

  • Issues in Wi-Fi networks

  • Wi-Fi Security

  • Advantages

  • Limitations


  • Wireless Technology is an alternative to Wired Technology, which is commonly used, for connecting devices in wireless mode.

  • A Wi-Fi is an electronic devices, such as a personal computer, video game console, Smartphone, or digital audio player can connect to the internet via a wireless network access point.

  • An access point (or hotspot) has a range of about 20 meters (65 feet) indoors as few rooms and a greater range outdoors, as many square miles.

  • Wi-Fi access can provide at Organizations and businesses such as homes, offices, airports, hotels and restaurants often provide free-use hotspots to attract or assist clients.


Wireless fidelity wi fi

How Wi-Fi works?

  • There are three most important items which makes Wi-Fi working in your laptop or desktop. These are,

    • Radio Signals

    • Wi-Fi Card which fits in your laptop or computer.

    • Hotspots which create Wi-Fi Network.

Wi fi technology

Wi-Fi Technology

  • Wi-Fi (Wireless Fidelity) is a generic term that refers to the IEEE 802.11 communications standard for Wireless Local Area Networks (WLANs).

  • IEEE 802.11 wireless LANs provides 1- or 2-Mbps transmission in the 2.4-GHz band using either frequency-hopping spread spectrum (FHSS) or direct-sequence spread spectrum (DSSS).

  • The 802.11 standard is defined through several specifications of WLANs such as,

    • IEEE 802.11b

    • IEEE 802.11a

    • IEEE 802.11g

Wireless fidelity wi fi

802.11 standards

How to connect wi fi network

How to connect Wi-Fi Network?

  • Basic concept is same as Walkie talkies.

  • A Wi-Fi hotspot is created by installing an access point to an internet connection.

  • An access point acts as a base station.

  • When Wi-Fi enabled device encounters a hotspot the device can then connect to that network wirelessly.

  • A single access point can support up to 30 users and can function within a range of 100 – 150 feet indoors and up to 300 feet outdoors.

  • Many access points can be connected to each other via Ethernet cables to create a single large network.

Wireless fidelity wi fi

Wi-Fi Access Protocol

  • MAC Protocols:

  • The 802.11 standards use a MAC layer known as CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance). In CSMA/CA a Wireless node that wants to transmit & performs the following sequence:

    • Listen on the desired channel.

    • If channel is idle (no active transmitters) it sends a packet.

    • If channel is busy then, the node waits until the transmission end then a contention period where minimum time a host must transmit before it can be sure that the no other host’s packet has collided with its transmission.

    • If the channel is still idle at the end of the contention period, then the node transmits its packet otherwise it repeats the process defined in step-3 above until it gets a free channel.

Wireless fidelity wi fi

Wi-Fi Applications

  • As Wi-Fi enabled devices have become more and more popular, wired devices are quickly becoming a thing of the past. Check out some of the new ways that Wi-Fi is being used below.

    • Home or office.

    • Large Corporations & Campuses

    • Small Businesses or SOHO.

Wireless fidelity wi fi

Whole house connectivity

Wireless fidelity wi fi

Public place connectivity

Wireless fidelity wi fi

Issues in Wi-Fi networks

  • Wireless technology doesn’t remove any old security issues, but introduces new ones.

    • Hidden Terminal Problem

    • Exposed Terminal Problem

    • MITM Attack(Man-in-the-middle attacks)

Wireless fidelity wi fi

Hidden Terminal Problem

  • The hidden node/ terminal problem found at a point to multipoint network and it is defined as being one in which three or more nodes are present. Let there are three nodes: node A, node B and node C.

    • A and C cannot hear each other.

    • A sends to B, C cannot receive A.

    • C wants to send B, C senses a free medium.

    • Collision occurs at B.

    • A cannot receive the collision.

    • A is hidden for C.

Wireless fidelity wi fi

Exposed Terminal Problem

  • Suppose there are four nodes: node A, node B, node C and node D.Here,

  • B can send to both A and C.

  • C can send to D, but not to A or B.

  • A and C cannot hear each other.

  • Now the Problem as follows -

  • When B transmits to A, C detects the transmission using the carrier sense mechanism.

  • So C defers transmitting to D.

  • But C could have sent to D, so blocked unnecessarily.

Wireless fidelity wi fi

MITM Attack

  • Attacker spoofes a disassociate message from the victim

  • The victim starts to look for a new access point, and the attacker advertises his own AP on a different channel, using the real AP’s MAC address

  • The attacker connects to the real AP using victim’s MAC address

Wireless fidelity wi fi

Wi-Fi Security Techniques

  • There are following security mechanisms in Wi-Fi networks.such as,

    • Wired Equivalent Privacy (WEP)

    • Wireless Protected Access (WPA)

Wireless fidelity wi fi

Wired Equivalent Privacy (WEP)

  • Provide same level of security as by wired network.

  • Uses RC4 based 40-or 104-bit encryption with pre-shared keys(static key) and 24 bit initialization vectors (IV).

  • Encrypt data only between 802.11 stations.once it enters the wired side of the network (between access point) WEP is no longer valid.

  • Security Issue with WEP

    • Short IV

    • Static key

  • Offers very little security at all.

Wireless fidelity wi fi

Wireless Protected Access (WPA)

  • This is a new standard from the Wi-Fi Alliance that uses the 40 or 104-bit WEP key, but it changes the key on each packet.

  • That changing key functionality is called the Temporal Key Integrity Protocol (TKIP).

  • Uses RC4,dynamic encryption with sessionkeys and 48 bit initialization vectors (IV).

  • Encryption provide Protection against man-in-the-middle attacks.

Wireless fidelity wi fi


  • Mobility

  • Ease of Installation

  • Flexibility

  • Cost

  • Reliability

  • Security

  • Use unlicensed part of the radio spectrum

  • Roaming

  • Speed

Wireless fidelity wi fi


  • Compatibility and Interpretability 

  • Billing Issues

  • Interference

  • Mobility

  • High power consumption

  • Limited range

  • Data security risks

Wireless fidelity wi fi


  • Wi-Fi is a universal wireless networking technology that utilizes radio frequencies to transfer data.

  • Wi-Fi allows for high speed Internet connections without the use of cables or wires.

  • It allows you to connect to the Internet from just about anywhere a coffee shop, a bed in a hotel room or a conference room at work without wires.

  • And the best thing of all, it's super fast almost 10 times faster than a regular dial-up connection.

Wireless fidelity wi fi

What is Next?

  • Now the focus in wireless is shifting to the wide area.

  • Wi-Max, short for Worldwide Interoperability for Microwave Access, is defined in IEEE 802.16 standards is designed to deliver a metro area broadband wireless access (BWA) service.

  • Wi-MAX is similar wireless system to Wi-Fi, but on a much larger scale and at faster speeds.

Wireless fidelity wi fi

Thank you

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