4 ms·

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

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.

TSiege 5y ago
portable wifi? edge case, but its possible this was the fix for it
tedunangst 5y ago
locationd probably wasn't tracking that state. Maybe now it is.
deleted 5y ago
[deleted]
spookthesunset 5y 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?
Zelizz 5y 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 5y ago
  "better experience" only if you aren't doing something latency-sensitive, like a video call.
  - Gigachad 5y 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.
    - gsich 5y ago
      1% packetloss is audible.
- NonNefarious 5y ago
Bud 5y 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.
IAmEveryone 5y 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 5y 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.
judge2020 5y 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.
midislack 4y ago
it's checking for nearby devices so it can upload them to "help" location accuracy

TSiege 5y ago

portable wifi? edge case, but its possible this was the fix for it

tedunangst 5y ago

locationd probably wasn't tracking that state. Maybe now it is.

deleted 5y ago

[deleted]

spookthesunset 5y 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?

Zelizz 5y 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 5y ago
"better experience" only if you aren't doing something latency-sensitive, like a video call.
- Gigachad 5y 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.
  - gsich 5y ago
    1% packetloss is audible.
NonNefarious 5y ago

Bud 5y 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.

IAmEveryone 5y 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 5y 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.

judge2020 5y 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.

midislack 4y ago

it's checking for nearby devices so it can upload them to "help" location accuracy