A new user posted a question about speed of travel affecting wifi, which was closed as Too Broad.

It seems a perfectly reasonable network theory question with pretty straightforward answers about doppler, getting out of wifi range, and current AP acquisition, which I gave in my answer. All of those are specific, falsifiable, and not book length -- hence I'd say not "too broad". At least three people upvoted.

Please can it be reopened? Perhaps there are other good answers.

Thanks for considering it.

  • 1
    Changed the tags per this answer on SE Meta. The difficulty is that there were so many close votes that I am reluctant to use the moderator privilege to simply reopen without a show of support from other users. – Ron Maupin Mod Apr 23 '19 at 14:07

The question is fundamentally one of physics. As asked -- and not particularly well asked -- the answer is "any non-zero speed", because if you're moving and the AP isn't, you will, eventually, move out of range. You answered the physics question -- you'd have to be moving pretty fast to be out of tuning tolerance. (and you aren't going to accelerate to that speed while associated.) The practical NE answer "depends"... what's the scanning rate of the client? Is it a static address, or do we have variability from DHCP? What's the sensitivity (i.e. range) of the AP and client? What's the terrain? How much traffic do you need to send/recv? It's not a simple "yes/no" question.

(This gets debated in racing circles every few months/years. Taking VIR as a case study (because I have), if you place your AP on the pit wall at the center of the front straight, your android/iDevice will be in range to associate and pass traffic for a few seconds before moving back out of range. If you place an antenna on the roof of the patriot building, you'll be in range for minutes - possibly continuous. 900MHz non-wifi equipment does away with the range and terrain problems.)

  • Thanks, very interesting. Is that en.wikipedia.org/wiki/Virginia_International_Raceway ? – jonathanjo Jun 14 '19 at 17:08
  • Yes. It doesn't help that it's one of the fastest places on the track. (and I did it when there was a tree there.) Other neat, useless trivia... the timing transponder is magnetic induction, not RF. (we discovered that entirely by accident with our EV race car -- DC motor: not a problem, AC motor: jams the timing loop.) – Ricky Jun 14 '19 at 19:55

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