GNSS: Subtle Improvements

Section by Brian Klug

Like the iPhone 4S and the iPhone 4 CDMA before it, Apple has gone with the GNSS (Global Navigation Satellite System) leveraging both GPS and Russian GLONASS which lives entirely on the Qualcomm baseband. In the case of the iPhone 4S and 4 CDMA, that was onboard MDM6610 and MDM6600 respectively, both of which implemented Qualcomm’s gpsOneGen 8 with GLONASS tier. Going to on-baseband GNSS is really the way of the future, and partially the reason why so many of the WLAN, BT, and FM combos don’t include any GNSS themselves (those partners know it as well). In this scheme GNSS simply uses a dedicated port on the transceiver for downconversion, additional filtering (on RTR8600), and then processing on the baseband. The advantage of doing it all here is that often it eliminates the need for another dedicated antenna for GNSS, and also all of the assist and seed information traditionally needed to speed up getting a GPS fix already exists basically for free on the baseband. We’re talking about both a basic location seed, precision clock data, in addition to ephemeris. In effect with all this already existing on the baseband, every GPS start is like a hot start.

There was a considerable bump in both tracking accuracy and time to an assisted GPS fix from the iPhone 4 which used a monolithic GPS receiver to the 4 CDMA and 4S MDM66x0 solution. I made a video last time showing just how dramatic that difference is even in filtered applications like Maps.app. GLONASS isn’t used all the time, but rather when GPS SNR is either low or the accuracy of the resulting fix is poor, or during initial lock.

With MDM9615 now being the baseband inside iPhone 5, not a whole lot changes when it comes to GNSS. MDM9615 implements gpsOneGen 8A instead of just 8, and I dug around to figure out what all has changed in this version. In version 8A Qualcomm has lowered power consumption and increased LTE coexistence with GPS and GLONASS, but otherwise functionality remains the same. MDM9x25 will bring about gpsOneGen 8B with GLONASS, but there aren’t any details about what changes in that particular bump.

I spent a lot of time playing with the iPhone 5 GNSS to make sure there aren’t any issues, and although iOS doesn’t expose direct NMEA data, things look to be implemented perfectly. Getting good location data is now even more important given Apple’s first party turn by turn maps solution. Thankfully fix times are fast, and getting a good fix even indoors with just a roof between you and clear sky is still totally possible.

Cellular Connectivity: LTE with MDM9615 WiFi: 2.4 and 5 GHz with BCM4334
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  • mjh483 - Sunday, December 02, 2012 - link

    This is by far the best in-depth review of iPhone 5. I really appreciate your effort in creating such a long review. Thank you very much and hope to see more of these reviews in future! Reply
  • galaxus1122 - Friday, December 28, 2012 - link

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  • galaxus1122 - Friday, December 28, 2012 - link

    Unlock your iphone at extremely cheap prices from unlockiphones.info . Such a great service they offer along with refund! Reply
  • WaltFrench - Saturday, March 09, 2013 - link

    I appreciate all the good thinking (and work) in this post, but really think you're being unrealistic in saying, <i>“In that case you could see no improvement or even a regression in battery life.”</i>

    Batteries exist to power actual usage. My old wristwatch — haven't worn it for a couple of years now — still keeps working just great. By the standard you mention, my watch is a far superior smartphone: no, I can't do as much browsing, but the battery life is better.

    I'm one who finds that LTE data speeds mean I spend MORE time each day browsing (chasing down links from Twitter, mostly) and the battery still lasts me a whole day. By an integrated test of how much good you can get from a phone in a day, the 5 has a <b>hugely better</b> on-the-go CPU/battery/screen combo than the iPhone4 it replaced.
    Reply
  • Amit kumar - Friday, March 22, 2013 - link

    Apple has done a splendid job with the iphone 5. It’s design outstanding. I checked full features of this device this site as well. http://www.gadtecho.com/iphone-5-specs/ Reply
  • ToniPan - Tuesday, April 30, 2013 - link

    3 Months with my new iPhone 5 and i always enjoy the sound quality when I capture videos or sound.
    The only problem is that everyone walking around with the same iPhone after 3GS.. I purchased a carbon sticker from http://www.coolcasing.com
    and i don't get bored from the same exactly design over and over. Why peoples talk about oranges(Galaxy S3-S4) when we talk about Apple?
    Reply
  • Andy_K1982 - Friday, August 09, 2013 - link

    Can anyone tell me how much data will it take to use FaceTime with someone? Reply
  • rabidpeach - Friday, September 13, 2013 - link

    Howdy,

    Did you ever do an article on why apple destroys android competition in GL graphics tests? Seems like no matter how many cores they throw in they can't quite catch apple.

    Thanks, sorry if I missed something.
    Reply

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