All the older versions of Wifi, except for Wifi-6, give each device on the network the entire bandwidth /highway no matter how small the amount of data it needs to transfer.

Can someone explain how video calls are reserved? If someone makes a video call using Wifi-6 then it will allot a particular section of the highway for the video call and the rest can be used by other devices.

Now, in the case of other lower versions of Wifi, I read that each device will get the entire highway to themselves whenever they need to transfer data.

So in the case of a video call, won't one device constantly have the entire highway to itself making no one else be able to connect to the Wifi? Then how am I able to use the Wifi when others are on a video call?

  • 1
    "So in the case of a video call, won't one device constantly have the entire highway to itself making no one else be able to connect to the Wifi?" Only for one frame, and VoIP frames are very small. Wi-Fi forces sharing of the medium, so one device cannot hog the entire medium.
    – Ron Maupin
    Sep 17 '20 at 18:28
  • Wow, So it happens so fast that it doesn't impact the smoothness of the video? Sep 17 '20 at 18:52
  • 3
    That is the point of packet-switched networks. Circuit-switching (traditional telephone service) dedicates an entire circuit to one thing, but packet switching (IP, including VoIP) breaks data into packets that get interleaved on a medium. The same thing happens on an ethernet switch where you have 48 users connected to the switch sharing the one uplink from the switch. There is also QoS for when links get congested that can give preference to certain types of traffic, but that is a huge subject.
    – Ron Maupin
    Sep 17 '20 at 18:55
  • Devices contend for air time with CSMA/CA using a pseudo-random backoff timer, with improved odds for voice and video frames. You may want to look into 802.11e (now in 802.11-2016) and DCF/EDCA to see how QoS functions in 802.11.
    – Yanzzee
    Oct 25 '20 at 7:11

A wireless radio network, is a shared medium. That means that only one sender at any time can be permitted to transmit. Multiple, simultaneous transmission would interfere with each other and garble the data.

However, packet-switched networks transmit data in frames, (practically) up to 1500 bytes in size. Transmitting 1500 bytes with e.g. 600 Mbit/s takes just (1500*8/600,000,000) = .00002 s or 20 microseconds. The network can transport at least 25,000 such frames per second, allowing the network to be used by many services and data streams "simultaneously" (within the perceptive scope of a human being).

Most often, bandwidth for voice or video calls is not reserved on wireless networks. The calls simply work as long as sufficient bandwidth is available. There are many schemes (QoS - quality of service) to reserve bandwidth and (try to) ensure timely delivery, but QoS is an extremely wide topic - especially for wireless - and cannot be generally covered within the scope of this site.

  • 1
    Also, VoIP packets are much, much smaller than 1500 bytes.
    – Ron Maupin
    Sep 17 '20 at 21:11
  • Wow, Okay so each device connected to the Wifi network gets about 20 microseconds of time with around 1500 bytes before it switches to another device connected to the Wifi network. Is that correct? Sep 18 '20 at 4:02
  • @RonMaupin Do reply please Sep 23 '20 at 5:47

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