WiFi Wireless Fidelity

Wireless Fidelity.

Th Brand name “WiFi” is used by WiFi alliance to describe WLAN products which follow IEEE 802.11 specification. WiFi Alliance. “Wi-Fi CERTIFIED” is a brand name of WiFi Alliance. It ensures the devices of different vendors are inter operable. It works on Data link layer and physical layer

  • IEEE 802.11.
  • WiFi or WLAN use ISM (Industrial, Scientific and Medical) band in 2.4 GHz region. ISM band is used for licensed free wireless transmission.
    UNII (Unlicensed National information Infrastructure) band in 5 GHz range.
See also:                OSI Layer         and         Communication System

Project 802.

In 1985 IEEE started a project 802. Named for the year and month (’80 Feb). Its goal was to set standards to establish communication between devices. It defines a family of protocols at Data link and physical layers.

802.1–overview of project 802, including higher layers and inter networking.
802.2-logical link control (LLC).
802.3- Ethernet – carrier sense multiple access with collision detect (CSMA/CD.
802.4-token bus.
802.5-token Ring.
802.6-metropolitan area network.
802.7-broadband technology.
802.8-optical fiber technology.
802.9-voice/data integration on LANs.
802.10-standard for inter operable LAN security.
802.11- WiFi.

WiFi benefits.

  • WiFi and ethernet both belong to LAN Standard family 802. Share some core elements.
  • Extended Access.
  • Cost Reduction.
  • Mobility.
  • Flexibility.


  • CSMA Carrier sense multiple access.
    This technique checks the shared media before transmission.It is applied by MAC layer.
  • CSMA / CD.
    It detects the collision and terminates the transmission immediately. It is mostly used in wired media where
  • CSMA / CA.
    It is more efficient than CSMA/CD. It detects the medium is free or busy. Transmitter waits until the medium is free. It is mostly used in wireless media.

Topology / Operating Mode.

  • Peer to Peer/Ad Hoc mode.

It enables devices to connect each other without the need of any central device or access point.

  • Client Server/Access Point/Infrastructure mode.

Devices are connected to access point. Access point performs the function of bridge between wire network and wireless network.


  • Wireless Station WSTA.
    A device that is connected to a WiFi network is called wireless station.It may be a PC, Laptop, Desktop, Mobile phone or etc.
  • Access Point AP.
    It is a device which connects multiple wireless stations.
  • Basic Service Set BSS.
    Basic service set is formed when two or more wireless devices are connected to the Access point AP.


  • MAC layer.

It is a sublayer of Data link layer. It controls the transmission across shared media. Its function in WiFi architecture is same as in ethernet architecture CSMA. Therefore, WiFi and Ethernet use the same format of MAC address.

  • Physical Layer.

It deals with the transmission of radio waves. ISM and UNII band are used for unlicensed radio transmission.

  • SSID Service Set Identifier.

AP broadcast its SSID in packet transmission. The client decides whether to connect or not on the basis of signal strength.

 EM Wave property.

Geometric Spreading Loss
Path Loss
Higher frequency covers less area due to line of sight nature.\Low frequency covers big area.


It was original standard support 1-2 Mbps. Operate at 2.4GHz.
Operate at 2.4GHz. Transmission range 100-150 feet. Speed 4-6 Mbps.
Operate at 5GHz. Transmission range 70-80 feet. Speed 15-17 Mbps.
Operate at 2.4 GHz. Transmission range 100-150 feet. Speed 20 Mbps.
Operate at 5GHz. It supports speed up to 30-40 Mbps
It supports up to 1GBPS or more

QoS, Speed, Range, Security

802.11e for QoS
802.11i for Security
802.11p for Data exchange between high-speed vehicle ( ITS Intelligent Transport System).

 Network Elements or Hardware.

  • Access point AP.
  • Wireless Router.
  • WiFi Card.

 Hotspot or Wireless zone.

It is a geographical area covered by one or more access points.

 How to setup WIFI.

Access point?
Internet ?
Access Point installation?
How to connect?
Troubleshoot connectivity?


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