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Comment by Nextgrid

4 years ago

I wonder why they keep rescanning the wifi environment even though the fact that it remains connected to the same BSSID and the RSSI doesn’t fluctuate too much should suggest that it’s very unlikely the device moved far enough to warrant another scan.

14 comments

Nextgrid

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Zelizz  4 years ago

My anecdotal experience (partially informed by working on the Windows Wi-Fi team) is that iOS/macOS are more aggressive about switching APs. It's a tradeoff - on one hand, you can have disruptive scans like this, but on the other, if it results in switching to a better network during a long period when the user is stationary, it can result in a better experience.

It also depends a lot on what your hardware is, whether you're doing a full scan or a partial scan, whether you have more than one NIC etc, etc.

  • not2b  4 years ago

    "better experience" only if you aren't doing something latency-sensitive, like a video call.

    • Gigachad  4 years ago

      Video calls aren't hyper latency sensitive, there is already a lot of latency in encoding and processing effects. I'd imagine this could be most disruptive to video games but this isn't a market Apple has done much to work with.

      1 reply →

spookthesunset  4 years ago

Maybe it wasn’t a problem worth fixing at the time? Maybe they’ll do exactly this in future versions of the location finder stack.

Edit: somebody pointed out that these scans could be for roaming purposes as well. Maybe there is another access point with a better signal and it’s time to move?

Bud  4 years ago

You're forgetting how sensitive this location detection is, these days. Let's say you are moving in a direction roughly parallel to the circle carved out by a given signal strength. You could move quite a long ways without RSSI fluctuating much.

judge2020  4 years ago

I imagine they have to handle the scenario where you're connected to a mobile access point and can't assume that 0 movement means you're in the same physical location. Watching other APs is going to provide a better picture.

IAmEveryone  4 years ago

What's the newest Wifi standard? ax? Anyway: it's quite... something? My standard router runs four different networks on two different IDs and if I understand it correctly, the fasted frequencies are subject to occasional use by... my local Patriot air defense system(?) which it needs to occasionally check for.

  • paranoidrobot  4 years ago

    > the fasted frequencies are subject to occasional use by... my local Patriot air defense system(?)

    I think you're you're talking about Radar detection?

    My apartment is on the approach-path for one runway of a major airport - I regularly get reports of Radar detection on my Unifi APs when planes are landing in this direction.