Video Description

WIFI- Wireless fidelity

  • LAN Protocol
  • IEEE 802.11
  • Standards: a,b,g, and n

    • Frequency
    • Speed
  • Works in ISM band
  • Uses 2.4 GHz and 5GHz
  • Frequency band divided into channels
  • Governed by WiFi Alliance

    802.11 Standard- WLAN standard

  • Uses air as transmission media
  • Concerned with the 2 lower layers of the OSI model
  • Data link layer

    • Logical link control (LLC)
    • Medium access control (MAC)
  • Physical layer

    • Physical layer convergence procedure (PLCP)
    • Physical medium dependent (PMD)

Infrastructure vs Ad-Hoc Modes- Infrastructure

  • Uses access point
  • Star topology
  • More commonly used
  • Ad-Hoc

    • Direct communication
    • Exists for short period
    • Suitable for meetings and conferences
    • More flexible in setup
    • Point-to-point

SSID- Service Set Identifier

  • Used to identify wireless LAN
  • Can be broadcasted or hidden
  • Length: 32 alphanumeric characters
  • Can be composed of several access points
  • Single access point can connect to several SSIDs

CSMA/CA- Carrier Sense Multiple Access Collision Avoidance

  • Uses request to send RTS and clear to send CTS to avoid collisions
  • Possibility of collision still exists
  • Lead to slower performance
  • Recovered by resending

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