WifiBasics

References https://www.cwnp.com/dynamic-frequency-selection/ Note: All figures taken from internet  Dynamic Frequency Selection In US and some other countries s ome of the Unlicensed National Information Infrastructure (U-NII) bands, 5.25-5.35 Ghz ( UNII -2) are used by radar systems. When wifi devices operate in these bands , they should not cause interference to the radar systems. Wlan devices operating in these bands or frequencies need to check periodically for the presence of any radar signals. If the device finds any radar signal, then it should not cause interference to the radar systems. The entire BSS must switch to a new channel. This process of detecting the radar signals and switching to a different channel is Dynamic frequency selection. DFS process consists of the following steps 1) Quieting the Channel: In an Infra structure network, the Ap schedules certain periods to be quiet periods where all the stations stop any transmiss...

Unicast frame buffer and DTIM Mobile Devices run on battery.  It is essential to conserve the battery power , to avoid frequent recharging of batteries and to have continued network connectivity.  The best  way to conserve power in wireless network is to turn off the transceiver. When the transceiver is turned off , it is said to be in sleep state or Doze state. When the transceiver is on, the mobile station is said to be in active state. By keeping a mobile station in sleeping state for a longer period of time , power can be conserved. To conserve power , stations go to sleeping mode also called power save mode. Station indicates to the AP that it is going to power save mode by sending a NULL data frame to the AP. This is a special kind of frame that has no frame body.  This  frame has only a MAC Header and FCS field.This frame can only be sent by a station to the AP. The power Management bit in the frame control field can be set to 1 or 0. Whe...

  Note : All figures/images taken from internet  Multiplexing Multiplexing is a technique used to share a Medium ( Cable, Wire, optical fiber, air). This allows simultaneous transfer of multiple signals in a single data link. The most simplest method of using the medium is to transmit one signal at a time. Multiplexing is a technique used to combine signals or information from different users/devices and transmit at the same time. Time Division multiplexing: Transmitting different users' digital signal over a single link by dividing the time into intervals called slots and allocating equal time slots to each user.       Statistical Time Division Multiplexing In this type of multiplexing, some users may have high priority or may have more data to transmit. Instead of allocating equal time slots to all users, depending on the priority, more time slots may be allotted to a particular use. Baseband systems can tranmsit on...