LTE frequencies and ROMS - T-Mobile Samsung Galaxy S 5

Hi guys, some super important info here, For anyone considering getting the international version should CONSIDER getting the T-mobile phone instead because it can utilize future LTE channel 700MHZ worldwide: (Assuming this is correct)
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Now with this information above,
I noticed the only difference between T-mobile's Samsung Galaxy S5 (G900T), and the international Version (G900F) Is that the LTE 700MHZ is missing from the international version.
This brings 2 important questions for BOTH users of both phones.
1. Now, Assuming the specs are correct on the G900T, (it appears to have future compatibility with 700MHZ being released by Tmobile, and other networks worldwide in 2014-2015.) We need to know if this is indeed correct or not.
2. I had flashed AllianceROM for the international version on my G900T, and it shows G900F in the about device.
Will this prevent any phone flashed in this manner from using 700 MHZ if the ROM is a G900F and flashed on a G900T. This is not important now, but will be very much so in the future as the cellular networks mature and roll out the AWS LTE band 700.
This is SUPER important as it may cause headaches for developers/users and mass confusion in the future if the issue isn't caught now before everyone starts using LTE 700 (AWS), and projects mature, and users may notice coverage gaps, if (2) above is confirmed to be a problem.

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solrazr said:
Hi guys, some super important info here, For anyone considering getting the international version should CONSIDER getting the T-mobile phone instead because it can utilize future LTE channel 700MHZ worldwide: (Assuming this is correct)
Now with this information above,
I noticed the only difference between T-mobile's Samsung Galaxy S5 (G900T), and the international Version (G900F) Is that the LTE 700MHZ is missing from the international version.
This brings 2 important questions for BOTH users of both phones.
1. Now, Assuming the specs are correct on the G900T, (it appears to have future compatibility with 700MHZ being released by Tmobile, and other networks worldwide in 2014-2015.) We need to know if this is indeed correct or not.
2. I had flashed AllianceROM for the international version on my G900T, and it shows G900F in the about device.
Will this prevent any phone flashed in this manner from using 700 MHZ if the ROM is a G900F and flashed on a G900T. This is not important now, but will be very much so in the future as the cellular networks mature and roll out the AWS LTE band 700.
This is SUPER important as it may cause headaches for developers/users and mass confusion in the future if the issue isn't caught now before everyone starts using LTE 700 (AWS), and projects mature, and users may notice coverage gaps, if (2) above is confirmed to be a problem.
Click to expand...
Click to collapse
Edit build.prop and you can make your phone appear as any model.

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Docmjldds said:
Edit build.prop and you can make your phone appear as any model.
Click to expand...
Click to collapse
Fair enough, however we need to get confirmation if the international ROM's are compatible and can utilize the 700 MHz LTE band (radio) on the G900T regardless of model displayed on the phone. I would think it *might* work, but without 700MHz available yet on T-mobile, I can't test it.

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Doesn't matter what ROM you installed ... If you actual phone has LTE bands than it wouldn't really matter what ROM you installed .... and like the other guy posted you can edit build.prop and make it to any model you want ...
Sent from my SM-N900T using Tapatalk

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Your answer is yes, just know when flashing a int rom, apn settings are for other bands. When I flashed alliance, I had to change apn settings to the LTE version. I know this for a fact cause I have 2 s5's and I had to copy its original settings to get LTE speeds
Sent from my Stanced Out S5

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Sometimes you don't need to set up apn's they set up by itself .. that's why I like tmobile
Sent from my SM-N900T using Tapatalk

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Looks like the gsmarena specs might be wrong, according to this LTE band 12 (700 MHz) is not supported on the SM-G900T:
http://www.samsung.com/us/mobile/cell-phones/SM-G900TZKATMB-specs

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solrazr said:
Hi guys, some super important info here, For anyone considering getting the international version should CONSIDER getting the T-mobile phone instead because it can utilize future LTE channel 700MHZ worldwide: (Assuming this is correct)
I noticed the only difference between T-mobile's Samsung Galaxy S5 (G900T), and the international Version (G900F) Is that the LTE 700MHZ is missing from the international version.
This brings 2 important questions for BOTH users of both phones.
1. Now, Assuming the specs are correct on the G900T, (it appears to have future compatibility with 700MHZ being released by Tmobile, and other networks worldwide in 2014-2015.) We need to know if this is indeed correct or not.
Click to expand...
Click to collapse
That's not the only difference:
T-Mobile (T) has LTE 700 & 1700 (Band 17/4), International version (F) does not. (mainly used in North America)
F has LTE 800 (Band 20), T does not. (mainly used in Europe)
F - WCDMA 850/900/1900/2100
T - WCDMA 850/1700&2100/1900/2100
I'm in Hong Kong where they sell unlocked F version but I travel to the US (and Europe) very often (have a place there) so I'm waiting to get a T-Mo version - which IMHO has the best world wide LTE coverage.

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I am confused and would very much appreciate if someone here who knows this stuff clear it out. According to these sites the T-Mobile 700 MHz block will be band 12 and the SM-G900T has band 17 which is a subset of band 12.
http://en.wikipedia.org/wiki/T-Mobile_US
http://en.wikipedia.org/wiki/E-UTRA#Frequency_bands_and_channel_bandwidths
So it seems to me that while our phones might be able to get on some 700 MHz LTE networks they would not be able to use the USA T-Mobile 700 MHz band?
Edit: Just found this:
"Annoyingly, both the AT&T and T-Mobile (SGS5) models lack LTE Band 12, which T-Mobile and some regional carriers are implementing at the end of this year to improve rural coverage, but no other phone has that yet, either."
http://www.pcmag.com/article2/0,2817,2456033,00.asp
Wondering if band 12 LTE access can be added through a modem upgrade...?

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rtwhtever said:
...
"Annoyingly, both the AT&T and T-Mobile (SGS5) models lack LTE Band 12, which T-Mobile and some regional carriers are implementing at the end of this year to improve rural coverage, but no other phone has that yet, either."
Wondering if band 12 LTE access can be added through a modem upgrade...?
Click to expand...
Click to collapse
More than likely, No.
Based on what I've read in other articles there is "physical" gap between the bands on 700mhz which requires filters on the PCB.
The S5 would have had to be shipped band 12 capable from the start or the hardware would have to be refreshed later in the year.
If the GS5 were band 12 capable you'd think they would try to market it as such, since that would be a major upsell.
I wouldn't hold my breath for a hardware refresh though. Seeing as the carriers (especially T-Mobile) seem to have a "hard time" trying to stock multiple internal storage and color options as it is, throw band 12 capable" and "not band 12 capable" and the whole system might collapse!

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Old topic ?
Flash an international S5 rom then flash a t-mobile radio.

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fffft said:
I'd say more than likely, yes.
Your information about SAW filters being necessary is out of date. The S5 has been reported to use the Qualcomm WTR1625L RF transceiver. This chipset is capable of operating on all LTE bands.
There may still be cost saving or protectionist measures in supporting hardware choices that limit us but given the available evidence, the overwhelming chances are that each variant can access an arbritrary set of LTE frequences and that the restrictions will be firmware based.
.
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Click to collapse
I stand corrected if that's the chipset used. I knew Samsung had been using SDRs I just was not aware that chips had become available to also dynamically handle the filtering.
Here's hoping it gets resubmitted to the FCC for band 12 approval later this year.

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fffft said:
Chipworks says that is the chipset and they should certainly know. The WTR1625L is release 10 compliant so it supports all 34 announced bands, not just the current bands in use. The companion WFR1620 chip in the photo is used for carrier aggregation which is LTE channel bonding to achieve higher speeds. Interestingly, Qualcomm's aggressive release schedule already puts a 28 nm successor on the table, the WTR3925 which will be the first single chip carrier aggregation solution to market. It will be release 11 compliant.
The move away from discrete filtering and aggressive push towards single IC systems is meant to capture a larger market share in this multi billion dollar market. Single chip solutions can hit cost and power reduction goals that discrete components could not reach.
The wild card, the possible hardware bottleneck will be the Avago RF front end. It's rumoured to be release 10 compliant as well, but since Avago only releases their specs and datasheets to qualified customers we can't be certain yet.
Click to expand...
Click to collapse
IFixit found a Qualcomm WTR1625L within when they did their teardown.

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mastarpete said:
I stand corrected if that's the chipset used. I knew Samsung had been using SDRs I just was not aware that chips had become available to also dynamically handle the filtering.
Click to expand...
Click to collapse
Gentlemen, all phones operating in full duplex mode require band-specific RF duplexers to separate the uplink and downlink frequencies and route the antenna to and from the receiver and transmit PA respectively. These are essentially paired RF filters. Duplexers serve the additional purpose of blocking out of band interferers including harmonics generated by the phone transmitting on other bands. Additional SAW and BAW filters are still required in the receive chain in some cases to block interference as well.
E-UTRA bands 1 through 32 are FDD bands and require duplexers. B12 requires its own duplexer. A tunable duplexer that can operate over several of the 700 MHz E-UTRA bands might be possible in the future, but for now a phone that can operate in LTE mode on AT&T (B17), Verizon (B13), US Cellular etc.(B12) requires multiple duplexers.
A phone operating in "All LTE bands" would require an unworkable number of duplexers. As a result, LTE phones are operator and region specific with respect to LTE, and right now it takes at least three SKUs to cover the main population regions and LTE operators across the world. The radio chipset is the same, but not the duplexers and usually not the RF power amps. Some phones will not operate on the right frequencies for LTE on some carrier networks without hardware changes.
Click to expand...
Click to collapse

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Ylo said:
Gentlemen, all phones operating in full duplex mode require band-specific RF duplexers to separate the uplink and downlink frequencies and route the antenna to and from the receiver and transmit PA respectively. These are essentially paired RF filters. Duplexers serve the additional purpose of blocking out of band interferers including harmonics generated by the phone transmitting on other bands. Additional SAW and BAW filters are still required in the receive chain in some cases to block interference as well.
E-UTRA bands 1 through 32 are FDD bands and require duplexers. B12 requires its own duplexer. A tunable duplexer that can operate over several of the 700 MHz E-UTRA bands might be possible in the future, but for now a phone that can operate in LTE mode on AT&T (B17), Verizon (B13), US Cellular etc.(B12) requires multiple duplexers.
A phone operating in "All LTE bands" would require an unworkable number of duplexers. As a result, LTE phones are operator and region specific with respect to LTE, and right now it takes at least three SKUs to cover the main population regions and LTE operators across the world. The radio chipset is the same, but not the duplexers and usually not the RF power amps. Some phones will not operate on the right frequencies for LTE on some carrier networks without hardware changes.
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Click to collapse
Interesting, thanks for sharing.
Click to expand...
Click to collapse

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Ylo said:
Gentlemen, all phones operating in full duplex mode require band-specific RF duplexers to separate the uplink and downlink frequencies and route the antenna to and from the receiver and transmit PA respectively. These are essentially paired RF filters. Duplexers serve the additional purpose of blocking out of band interferers including harmonics generated by the phone transmitting on other bands. Additional SAW and BAW filters are still required in the receive chain in some cases to block interference as well.
E-UTRA bands 1 through 32 are FDD bands and require duplexers. B12 requires its own duplexer. A tunable duplexer that can operate over several of the 700 MHz E-UTRA bands might be possible in the future, but for now a phone that can operate in LTE mode on AT&T (B17), Verizon (B13), US Cellular etc.(B12) requires multiple duplexers.
A phone operating in "All LTE bands" would require an unworkable number of duplexers. As a result, LTE phones are operator and region specific with respect to LTE, and right now it takes at least three SKUs to cover the main population regions and LTE operators across the world. The radio chipset is the same, but not the duplexers and usually not the RF power amps. Some phones will not operate on the right frequencies for LTE on some carrier networks without hardware changes.
Click to expand...
Click to collapse
Thanks for the response.
When I google the WTR1625L the results I'm seeing are claiming it is Release 10 based and supports all announced bands. Maybe their wording is over simplifying but it seems to imply it's capable of handling the duplexing, antenna switching and basic filtering as one combined chipset.
I understand that there could still be a possibility of needing additional interference filtering.
Are you pointing out that the WTR1625L really only has selective support based on how the OEM builds out the chipset?
ie. Hardware wise (ignoring software configuration), if the OEM using the WTR1625L gets a request to not include (or doesn't ask for) a specific band they wont actually physically assemble it in a way that supports all bands.
Edit: here's a link to the press release from when the WTR1625L was announced.
http://www.multivu.com/mnr/60452-qualcomm-rf360-front-end-solution-global-4g-lte-for-mobile-devices
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Click to collapse

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fffft said:
The observations about discrete components being a limiting factor was accurate five years ago. It largely out of date now and specifically has little relevance to the specific chipset under discussion. This chipset is release 10 compliant and only requires minimal external hardware support.
A RF front end is still required, but as the current generation of Avago chips have made comparable advances and are also R10 compliant. The days when we needed a slew of SAW filters and other discrete components are behind us.
Between that and general manufacturing practice, it is all but certain that the in situ chipset can support all existing GSM and LTE bands. The (artificial) restrictions will be in the firmware.
.
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Any new thoughts or information on this discussion?