wireless fidelity wi fi n.
Skip this Video
Loading SlideShow in 5 Seconds..
Wireless Fidelity ( Wi-Fi ) PowerPoint Presentation
Download Presentation
Wireless Fidelity ( Wi-Fi )

Loading in 2 Seconds...

play fullscreen
1 / 23

Wireless Fidelity ( Wi-Fi ) - PowerPoint PPT Presentation

  • Uploaded on

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

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
Download Presentation

PowerPoint Slideshow about 'Wireless Fidelity ( Wi-Fi )' - sybill-wong

Download Now An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
wireless fidelity wi fi
Wireless Fidelity(Wi-Fi)

Submitted by,

Premsingh Thangasamy.S


I year M.Tech

Network Engineering



  • 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.



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
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.

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.

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.

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)

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.

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.

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

Wi-Fi Security Techniques

  • There are following security mechanisms in Wi-Fi networks.such as,
      • Wired Equivalent Privacy (WEP)
      • Wireless Protected Access (WPA)

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 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.


  • Mobility
  • Ease of Installation
  • Flexibility
  • Cost
  • Reliability
  • Security
  • Use unlicensed part of the radio spectrum
  • Roaming
  • Speed


  • Compatibility and Interpretability 
  • Billing Issues
  • Interference
  • Mobility
  • High power consumption
  • Limited range
  • Data security risks


  • 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.

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.