Will the iPhone's A-GPS technology work outside of 3G networks?

Discussion in 'iPhone' started by slate1, Jun 17, 2008.

  1. slate1 macrumors regular

    Sep 12, 2006
    Title pretty much says it all.

    Everyone is getting all excited about the new iPhone being 3G compatible, but if you've looked at the AT&T 3G map you'll quickly discover that if you're not well within a major metropolitan area you're screwed as far as 3G reception.

    I know the A-GPS technology uses cell towers to triangulate position and was just wondering if that was only true within 3G networks or if it will work network-wide.
  2. LiveForever macrumors 6502

    Dec 13, 2007
    GPS uses satellites and my 3G phone still displays cell tower info even in 2.5G areas so I say it probably will but GPS is not network dependant.
  3. diamond.g macrumors 603


    Mar 20, 2007
    A-GPS is still real GPS, it just uses the towers to find you faster.
  4. kdarling macrumors P6


    Jun 9, 2007
    First university coding class = 47 years ago
    Always repeat your question inside your post anyway, please :) There is no title shown this far down.

    We don't know nearly enough about the A-GPS in the iPhone to answer well.

    Most GSM A-GPS implementations will work over the lowliest GPRS connections. No 3G required.

    But the assisted part might not work if you're roaming on another carrier.

    Again, no one knows what kind of A-GPS is used. Especially since it depends on the carrier. There are many countries and carriers.

    However, most do NOT fall back on tower triangulation unless no GPS signal can be obtained, such as when you're inside a building. This is carrier dependent.

    From what Apple's websites say, it looks like the iPhone's A-GPS implementation is the normal simple version: first, it gets assistance finding satellites. After that, everything is internal. It tries to use its GPS. If it can't, then we leave the GPS realm and it tries to use the WiFi hotspot and then cell id methods as before.

    It also depends on the controlling application's location request... with a good location API, an app can ask for more or less accuracy, which might or not use the GPS at all.
  5. rayward macrumors 68000

    Mar 13, 2007
    Houston, TX
    Maybe I'm wrong here, but I think the 3G issue will be the refresh rate of the map. Presumably the GPS will know where you are at all times, but you're dependent on your data transfer speed for the Google app to build the map. If you're moving quickly but on a slow connection, the map won't keep up with the GPS location information.

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