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A comment on Google, Microsoft, Comcast Say Verizon’s New Cellular Tech Could Wreck Wi-Fi. Parent comment

Re:Google, Microsoft, Comcast Say Verizon’s New Cellular Tec... by ploxiln on Monday December 07, 2015 @02:03PM (#10691763)
20 or so SSIDs beaconing adds up to a lot of airtime. Consider:

  * beacons are sent at a low "common" rate, perhaps 6mbps
  * beacons still include the preamble and the DIFS before that
  * 802.11n/ac get high bandwidth from aggregating multiple frames
So all those trivially small beacons take little bandwidth but a significant amount of airtime (which is a significant amount of potential bandwidth for faster clients with multiple frames to send in one aggregate)

https://en.wikipedia.org/wiki/Distributed_coordination_funct...

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Re:Google, Microsoft, Comcast Say Verizon’s New Cellular Tec... by qb45 on Monday December 07, 2015 @03:08PM (#10692292)
That's true. Most 2.4GHz networks beacon at 1Mbps, which is because they are typically configured for compatibility down to 802.11b and beacons are transmitted at the lowest enabled speed.

Here [1] somebody collected measurements of time eaten by beacons at few configurations. Not a complete disaster, but still somewhat significant. For example, at the place where I am now, I'm receiving 67 beacons per second (all at 1Mbps), which, according to those calculation, wastes 17% of airtime.

[1] http://wifinigel.blogspot.com/2013/08/its-well-known-rule-of...

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Re:Google, Microsoft, Comcast Say Verizon’s New Cellular Tec... by ploxiln on Monday December 07, 2015 @03:24PM (#10692407)
That's a great link / experiment, thanks.

By just counting the literal airtime of the beacons, I think it underestimates the effects a bit, because it doesn't account for the contention of the remaining air time, which would be reflected in increased collisions and small delays which (sorry to be hand-wavy again) can add up. I think if he ran some application-level tests at the same time (perhaps iperf, perhaps something more sophisticated) he would see a bigger impact to "good-put".

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