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Have you used an iPhone / Android device? Because Google and Apple have pretty much nailed this. That is exactly what they have: a database with ENOUGH of the

Have you used an iPhone / Android device? Because Google and Apple have pretty much nailed this. That is exactly what they have: a database with ENOUGH of the GSM (CMDS) basestatio cellids and WLAN identifiers, linked to real coordinates, so that most of the time things "just work". So all the phone needs is to use some mobile data to get this database, at least once before it caches the local id => coordinates information. After this, a rough location is available even without GPS. How can they do this? Because everytime someone somewhere uses Google Maps with GPS, they are also submitting data to Google's cellid and WLAN databases. So it works really well in countries and areas with lots of smartphone users, and less so when you go to the outskirts of the Philippines. Also: Landmarks work pretty well even with the non exact cellid location, you definitely don't need to have GPS enabled to use the app. This is basic platform functionality, which is why we didn't emphasize it in the text: However maybe we should add some information about this as well.

roel_v 15y ago
Yes, I've had and actively used an Android for about a year and half now. I use it quite extensively, have bought a number of applications and I guess I'm basically the audience you're targeting - people who actively go out to find, and potentially buy, applications (this group is imo a relatively small subset of all Android users, I know many more Android users who have never used the Market than those who have). Anyway just to make it clear that it is, imo, not to be considered 'well known' information amongst the general Android-using population. Heck, I've even written toy Android applications, and I still didn't know.
- asmosoinio 15y ago
  Thanks for the insight! I guess I've been to involved in location stuff for a while. You'll get a feel of the location system with Google Maps quite easily: You get a big light blue circle around "own location" when location comes from mobile network cellid, and a smaller one when it uses WLAN-based location. That signifies the accuracy. And it does indeed find this location even when GPS is off. And this works even when "Mobile network"-setting is off, i.e. the phone is not sending or receiving any data, if you are still connected to a previously known mobile cell. Anecdotally: I moved a few months ago, and didn't change my WLAN network id. At my new place, when GPS was not available, Google Maps was showing my location to my old place. This continued until I renamed the WLAN and used Google Maps with GPS near my new place. This shows the weakness of crowdsourced location data, but such incidents are rare enough that it basically "just works".

roel_v 15y ago

Yes, I've had and actively used an Android for about a year and half now. I use it quite extensively, have bought a number of applications and I guess I'm basically the audience you're targeting - people who actively go out to find, and potentially buy, applications (this group is imo a relatively small subset of all Android users, I know many more Android users who have never used the Market than those who have). Anyway just to make it clear that it is, imo, not to be considered 'well known' information amongst the general Android-using population. Heck, I've even written toy Android applications, and I still didn't know.

asmosoinio 15y ago
Thanks for the insight! I guess I've been to involved in location stuff for a while. You'll get a feel of the location system with Google Maps quite easily: You get a big light blue circle around "own location" when location comes from mobile network cellid, and a smaller one when it uses WLAN-based location. That signifies the accuracy. And it does indeed find this location even when GPS is off. And this works even when "Mobile network"-setting is off, i.e. the phone is not sending or receiving any data, if you are still connected to a previously known mobile cell. Anecdotally: I moved a few months ago, and didn't change my WLAN network id. At my new place, when GPS was not available, Google Maps was showing my location to my old place. This continued until I renamed the WLAN and used Google Maps with GPS near my new place. This shows the weakness of crowdsourced location data, but such incidents are rare enough that it basically "just works".