gOS proxy for A-GPS

Oggyo

de0u If you want really fast fixes even when you are completely indoors, run Google's stock OS, which uses their database of Wi-Fi access points, but serves as a data-collection platform for Google

Is this the only solution for indoor fixes, I mean the stock OS?
I asked in the past that I would like to achieve this on Graphene OS - https://discuss.grapheneos.org/d/10392-indoor-location

de0u

Oggyo Is this the only solution for indoor fixes, I mean the stock OS?

Not in a mathematical sense! But I am unaware of a GrapheneOS port of UnifiedNLP or of a reimplementation. There are occasional questions, e.g.:

GrapheneOS

SUPL is only used when cellular is enabled and there's an active carrier. SUPL has multiple modes and the normal mode that's used by GrapheneOS doesn't leak much information. It downloads a database without submitting much data. It leaks your carrier to the server to get a database for that carrier. SUPL in the more aggressive mode can be used to determine location by itself but that's not available as a toggle in AOSP or the stock OS so it's not there as an option in GrapheneOS either. The more aggressive mode would leak your location to the SUPL provider.

PSDS downloads are static databases and can be cached for a long period of time.

graphenediscoverer4 No, the standard server for Pixels is the Google server, not Broadcom.

graphenediscoverer4 GNSS works fine without PSDS or SUPL. PSDS and SUPL make it obtain a location fix much faster. It works without them, but very slowly if neither is available. PSDS is quite important for it to obtain a fix in a reasonable amount of time which only requires a network connection to retrieve static databases while SUPL is a bonus making it even faster. PSDS lasts for a long time before it's fully expired. You can go days without network access and it can still provide useful data to speed up the location fix.

de0u It's on the device where sending IMSI and phone number for SUPL was disabled, and similarly disabling sending metadata for Qualcomm PSDS. Qualcomm devices are nearly all obsolete so that's not particularly relevant anymore. Only the Pixel 5a still has privacy/security updates. You won't have privacy or security on an end-of-life device and being concerned about all these details doesn't make any sense for them.

de0u

GrapheneOS It's on the device where sending IMSI and phone number for SUPL was disabled, and similarly disabling sending metadata for Qualcomm PSDS.

Thanks for the clarification!

Any time unnecessary device identifiers can be suppressed that's a good thing.

GrapheneOS

de0u IDs aren't sent to any service used by GrapheneOS and aren't available to regular apps, so only explicitly used OS functionality such as eSIM activation can result in them being sent to a service. The standard user agent for URLConnection does include device model and BUILD_ID. We make sure that the BUILD_ID matches the current stock OS release by overriding it when we use a newer AOSP revision than the stock OS to avoid fingerprinting based on that. It would be better if it was omitted from the user agent altogether but omitting it ourselves would likely be worse than making it match the stock OS due to the deliberately small number of supported devices for GrapheneOS.

GrapheneOS

Additionally, using Google's network location service on GrapheneOS is fully supported as part of sandboxed Google Play but requires several configuration steps. By default, location requests to Google Play are rerouted to the OS location service.

We don't currently offer a toggle for the OS to use it as an OS network location service, which is how it works on the stock OS, where using network location via the OS location API results in querying Google Play. We do the opposite by default, where querying Google Play instead queries the OS. We could provide a 3rd value for the toggle to do what the stock OS does. However, most apps from the Play Store which use network location query Google Play for it rather than the OS so their network location support works fine on GrapheneOS already.

We plan to provide alternative network location services in the future, but UnifiedNLP does not suit our needs for multiple reasons. It should not be tied to Google Play compatibility. We already provide a better system for providing Google Play location API compatibility for regular OS network location services and location in general.

GrapheneOS emulates network location so apps only using network location without the ability to use regular GNSS location can still work, but you may need to use an app like GPSTest to bootstrap them.

graphenediscoverer4

de0u If you want really fast fixes even when you are completely indoors, run Google's stock OS, which uses their database of Wi-Fi access points, but serves as a data-collection platform for Google

I haven't been in the US in a while, you say this because google recently became an ISP isn't it? Or do ISP of other countries also give them their mapping of AP IP address <-> geographical address ?

graphenediscoverer4

graphenediscoverer4 Nevermind I got my answer here thanks :

Would it be possible to use something like https://f-droid.org/en/packages/helium314.localbackend/ ?
It builds a database locally, basically just saying: Do I have a good GPS fix? If yes, what are the wifi networks around? Users would end up with a good database for all the locations they commonly are at pretty quickly.

It is at present set up to use unifiedNLP, but in principle something like this doesn't need to use that. I wonder how much work it would be to fork it and integrate it into GrapheneOS?
https://discuss.grapheneos.org/d/859-unifiednlp-options/2

So google gives a fix to their worldwide users and retrieve SSID names around them to build a database...

ToffoliGate

Dear GrapheneOS users,
this conversation is very interesting; I've realised only now that GPS on its own is a receive-only technology, and is thus (very) private. Fascinating stuff.

However, I am encountering a problem. I am currently in another country, and thus in roaming. Roaming is supported by my carrier, so do not have any trouble navigating the web and writing this message. But I cannot, in any way, make the GPS work. I need maps for navigation, and without precise location I does not really work.

On the phone I'm currently using while travelling (Pixel 7 Pro with latest GOS) I have Google play services, I have activated SUPL and PSDS data, I have activated even the Wi-Fi search and, in a last desperate attempt, even given permission to Google to use fine location data. But the signal won't get acquired. I left the phone for about 10 minutes with GPS on, near the open air, and it didn't acquire any signal.

Now, based on my understanding of this thread, the SUPL data is carrier-specific, and so maybe this is the reason why is does not work. But it isn't mentioned anywhere that is should not work in roaming. Also, a GPS signal should be acquired even if constellation data is not available, but it does not seem to be the case, as after several minutes I still didn't acquire any signal.

This is not the only time I had problems with GPS. Some moths ago, while travelling to a European country, I encountered the exact same problem: the GPS did not acquire any signal. On the other hand, in my country I have never encountered a problem, even with the more restrictive and private GrapheneOS-provided user plane data, and I always acquired the GPS signal lightningly fast.

Should I disable all assisted-GPS data and leave the phone to acquire the constellation data on its own, and then permanently leave the location turned on and activate SUPL and PSDS to acquire more precise data?

Thank you, and have a nice day.

treequell

ToffoliGate You'll want to leave SUPL and PSDS activated to improve getting a location lock. Are you standing outside when looking for location? Have you tried fetching location with the GPSTest app? That tends to help, and you can see which satellites your device is receiving from.

If it doesn't work with the GPSTest app, and you require location, you could trying routing location requests via Google Play Services. To do that you would need to give Google Play Services unrestricted access to your location, and configure it in the Google Play Services configuration menu, following the instructions given here: https://grapheneos.org/usage#sandboxed-google-play-configuration

ToffoliGate

treequell Hi, thank you for you fast and on point reply, and sorry for my delayed one but I was busy.

Yes, I tried using the app GPStest (which I didn't know and have never used before, but seems cool), and after some little time it found some satellites and connected to them. So this did help.

But I think it still does not use the WiFi and othe cell tower databases. For now, the accuracy seems fine, but it is still not as granular as with a stock Pixel with stock Google Play services. I still haven't granted full control to locations and nearby devices to the Google services as specified in the guide, because I did not feel comfortable doing so; so that's maybe why the positioning is still not quite precise.

But, as per my understanding, without Google services, just relying on GOS' implementation of SUPL should be enough to get a precise and fast GOS signal, right? So I don't understand why I can't obtain this data. I stress this again: I am in roaming, and with the same settings in my country using my carrier I get the positioning very fast just with the GrapheneOS settings. Can the roaming affect in any way this data?

Edit: maybe I will follow the guide and grant Google services access to everything it needs to download positioning data based on networks. If I'll do this, I'll update this thread. For now I tank you again for your support.

de0u

ToffoliGate For now, the accuracy seems fine, but it is still not as granular as with a stock Pixel with stock Google Play services. I still haven't granted full control to locations and nearby devices to the Google services as specified in the guide, because I did not feel comfortable doing so; so that's maybe why the positioning is still not quite precise.

Google went to the trouble of mapping cellular base stations and especially Wi-Fi access points because they believed it would improve both speed and accuracy of localization. While the GrapheneOS project aspires to cooperate with beaconDB to deliver something similar, that has not yet occurred.

ToffoliGate I stress this again: I am in roaming, and with the same settings in my country using my carrier I get the positioning very fast just with the GrapheneOS settings. Can the roaming affect in any way this data?

It is not obvious how either the legal issue (which country you are in) or the carrier issue would harm GPS localization, but if you are in a different country you might plausibly be in a different geography: mountains instead of plains, tall buildings instead of short buildings, noisier radio environment instead of quieter... given the information provided so far it's hard to say.

ToffoliGate

de0u Than you. The geography was not a problem, since it was similar to that of my country. I don't know why, maybe it didn't have time to download all the location data, or maybe I misconfigured something. But now everything seems to be working fine, and the A-GPS quickly an precisely finds my location (I gave all the standard permissions to the google services, and configured GOS to use google's services for location data).
I will update in the future if any other problems arise. For now I thank you.

de0u

ToffoliGate Thanks for reporting back! I'm glad it's working.

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