4G Question

Discussion in 'iPhone' started by JetBlack7, Jul 23, 2012.

  1. JetBlack7 macrumors 68020

    JetBlack7

    Joined:
    May 14, 2011
    Location:
    Portugal
    #1
    Can anyone tell me how does 4G work on the iPhone? Do you turn on 3G and then it automatically shows 4G in covered areas?

    And do you feel a difference between 4G and 3G? Is it much faster or not that fast?
     
  2. jav6454 macrumors P6

    jav6454

    Joined:
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    #2
    Its a whole HSPA v HSPA+ network. The 4G symbol appears when you are in an area with HSPA+ technology in the network. Otherwise you'll be in 3G.

    The difference is download speeds seen. With HSPA you are limited to 7.2 Mb/s vs HSPA+ can go from 14.4 Mb/s to 42.2 Mb/s (using 4x4 Multiple-In Multiple-Out, MIMO antenna system) with software updates.

    Of coarse all of these are theoretical maximums (assuming perfect line of sight, no interference, no traffic [little if any], and supporting carrier backhaul)
     
  3. Intell macrumors P6

    Intell

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    #3
    On the AT&T iPhone 4S running iOS 5.1 and higher, the only data indicatoers you'll see are none, GPRS, EDGE, and 4G. It will never show 3G, even if the area is HSPA only.

    It shouldn't even show 4G at all. Seeing that neither HSPA+ or LTE is 4G, but still only 3G.
     
  4. jav6454 macrumors P6

    jav6454

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    #4
    This is also true. However, I have seen 3G be shown when out of HSPA+ range.
     
  5. Intell macrumors P6

    Intell

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    #5
    The AT&T bundle the 4S' 5.1+ firmware is setup to not allow the 3G symbol to show at all. The DataIndicatorOverride is key is set to 4G and the DataExclusionOverride key is set to 3G.
     
  6. jav6454 macrumors P6

    jav6454

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    #6
    Engrish?
     
  7. Intell macrumors P6

    Intell

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    #7
    The AT&t carrier bundle in the iPhone 4S' 5.1 firmware is version 12.0. Starting with version 12 AT&T has set some keys within the property list defining what the iPhone can do on their network and how it is to interact with their network. On of the keys, that is unique to AT&T on the 4S, is DataIndicatorOverride. This key overrides the highest data indicator on the device, in this case 3G. It resets it to 4G. The other key is DataExclusionOverride, this key is rare and only in a few other bundles. It's job is to exclude a certain data indicator and force it to present the previous one or the next highest one. In the few instances that is appears, it is to remove the GPRS circle from showing. In AT&T's case, it is to prevent the 3G symbol from showing and instead presents the 4G symbol.
     
  8. cynics macrumors G3

    Joined:
    Jan 8, 2012
    #8
    Through means of black magic the number 3 was replaced with a 4 in anything better then EDGE.
     
  9. AFDoc macrumors 68030

    Joined:
    Jun 29, 2012
    Location:
    Colorado Springs USA for now
    #9
    I agree with you but the people that decide such things don't. HSPA+ is 4g according to those in charge, that is all.
     
  10. Intell macrumors P6

    Intell

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    #10
    AT&T's marketing department is not in charge. Neither is T-Mobile's who originally called HSPA+ 4G. The ITU are the ones that dictate what standard is called what and the speeds set fourth by them have established that to be called 4G with wireless service must get 100Mpbs in a vehicle moving at highway speeds. Currently nothing outside of research labs gets that fast.
     
  11. JetBlack7 thread starter macrumors 68020

    JetBlack7

    Joined:
    May 14, 2011
    Location:
    Portugal
    #11
    Mkay....

    So, I have an iPhone 4S and now acquired my vodafone 4G ready SIM card, so when I'm on an 4G covered area, it will show automatically 4G?
     
  12. Intell macrumors P6

    Intell

    Joined:
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    #12
    The 4G only shows when the phone in on AT&T. Otherwise, it'll show 3G.
     

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