update and expand SUPL documentation

This commit is contained in:
Daniel Micay 2023-03-06 13:40:50 -05:00
parent 8649a94b53
commit abbafc931b

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@ -1038,14 +1038,30 @@
normally, you can remove the <code>dun</code> APN type from your APN normally, you can remove the <code>dun</code> APN type from your APN
configuration.</p> configuration.</p>
<p>If your chosen carrier includes the <code>supl</code> APN type in their APN <p>When you have both a cellular connection and Location enabled, control plane
configuration, SUPL will be used to provide A-GNSS in order to greatly improve and/or user plane (SUPL) A-GNSS is used in addition to PSDS to greatly reduce
location lock time for GNSS (GPS, GLONASS, etc.). The fallback SUPL server is the time needed for GNSS to obtain an initial location lock. These obtain
<code>supl.google.com</code> if the carrier doesn't choose a specific one. You coarse location info from a server based on nearby cell towers. Control plane
can remove <code>supl</code> from APN types if you don't want to use this, but A-GNSS is provided by the cellular connection itself and therefore doesn't
it will greatly increase GNSS location lock time if your carrier lacks control have any real privacy implications while SUPL connects to a server often not
plane A-GNSS via the cellular network and fully relies on user plane A-GNSS provided by the carrier. Most A-GNSS services only accelerate obtaining a satellite-based
(SUPL) to provide this instead.</p> location and won't provide an estimate on their own. The carrier can choose a
SUPL server as part of their carrier configuration but most leave it at the
default of supl.google.com. By default, GrapheneOS overrides the
carrier/fallback SUPL server and uses the supl.grapheneos.org proxy. GrapheneOS adds a
toggle for configuring SUPL in Settings ➔ Location where you can choose
between the default supl.grapheneos.org proxy, the standard server
(carrier/fallback) or disabling it completely. GrapheneOS also disables
sending IMSI and phone number as part of SUPL. Pixels with a Qualcomm baseband
use it to provide both cellular and GNSS including both control plane and user
plane A-GNSS being implemented inside the baseband. For Qualcomm baseband
devices, SUPL is only enabled if the APN configuration for the carrier
includes <code>supl</code> as an APN type. Pixels with a Samsung baseband have
a separate Broadcom GNSS chip without integration between them so SUPL is done
by the OS with regular networking (can use Wi-Fi and VPN) and SUPL is used
regardless of the carrier's APN type configuration. GrapheneOS upgrades the
Broadcom SUPL implementation to only using TLSv1.2 instead of using TLSv1.1
and older.</p>
<p>MMS, RCS, SMS over LTE, VVM (Visual Voicemail), VoLTE (carrier-based calls <p>MMS, RCS, SMS over LTE, VVM (Visual Voicemail), VoLTE (carrier-based calls
on 4G and higher) and VoWi-Fi are largely implemented by the OS via TCP/IP on 4G and higher) and VoWi-Fi are largely implemented by the OS via TCP/IP