TD-LTE vs FD-LTE

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Ockie

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Henceforth AKA OckieMoto :-)
So I have been wondering for a while why Telkom decided to go with a specification of LTE that seems to be downright silly and not compatible with any phones being sold in SA. A peep on mybb replied to one of my posts that touched on this subject and he mentioned something to the effect that TD-LTE is actually a bit better than FD-LTE that Vodacom and MTN is deploying. I decided to do some reading, and he indeed seemed to be correct. Not speedwise, as they botth seem to be pretty equal on that side, but spectrum efficiency TD seems to be the way to go, specially for countries like us where spectrum is at a premium thanks to our incompetent douches in government and ICASA and any other government agency you can come up with.

I thought I would make a thread about this as I have not really seen a article on mybb regarding this that explains the how, why and what of this matter in a South African perspective and views from our networks. What do you guys think of this? Should other networks be deploying TD like Telkom or stick with FD like Vodacom, or do a combination of both? What does make it rather complex is the fact that most phones seems to suppord only FD like the Samsung etc. Some phones like the Iphone 6 supports TD, and also the Huawei Honor 6, but most phones being sold here is FD only.

Opinions? Would like to hear if Jannie has some words of wisdom and his personal opinion and maybe the official standing of Vodacom no the matter also. Think it is a rather interesting topic.


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Samsung's not one to shy away from releasing zillions of different versions of essentially the same phone, but its two latest models are intriguing in one specific way. The Galaxy S4 and S4 Mini are getting 'TDD/FDD Dual Mode LTE' versions, the company has announced. What the what?

LTE is the formal name for 4G, meaning Long Term Evolution. But similar to America's different, incompatible GSM and CDMA phone systems, there are two different standards for LTE -- TDD and FDD. The good news is you can make phones that are compatible with both standards, as Samsung has just proved.

These two abbreviations stand for 'time-division duplexing' and 'frequency-division duplexing'. They're two different methods of cramming data and phone calls into the connection to your friendly local phone tower.

Duplexing is just where your phone can transmit and receive at the same time, unlike a walkie-talkie, which can only do one at once (this is called simplexing). TDD means the transmission and reception occur on the same frequency, but each only for a split second, alternating between the two. That's great for mobile Internet use, because you can use more of the bandwidth available for either downloading or uploading, whichever you happen to be doing.

FDD, meanwhile, means you're using a slightly different frequency for uploading and downloading. The benefit of this method is less possible interference -- better reception. It's unclear which standard gives faster downloads, and it would be difficult to eliminate all the possible variables to produce a meaningful answer.

What does this mean for you?
The real difference between the two systems is where they're used, and therefore where you can use your 4G phone. Here in the UK, EE uses FDD and everyone else will too.

"While the majority of the global LTE market is based on FDD-LTE technology, TDD-LTE, the alternative LTE technology, is expected to see increased adoption in the US, China, Australia, Middle East, Northern and Eastern Europe, and Southwest Asia, and to gain a more pronounced position in the global LTE market," Samsung says. "Seamless handover between FDD-LTE and TDD-LTE networks is a critical feature for end-user customers and mobile operators, especially in markets where the both technologies are deployed."

China's biggest phone company, China Mobile, is rolling out TDD, and industry watchers expect it to expand around the world. Australian network Optus has both, but because it's such a big country the spectrum is divided up by region and in the capital, Canberra, it can only supply TDD.

This kind of fragmentation is likely to become more common, as Samsung says, as networks put in place agreements to allow 4G roaming, and people upgrade their phones and are willing to pay for 4G on their holibobs. So phones like the new S4 and S4 Mini that can nimbly swap between the two will become important for glamorous global jetsetters like you, dear reader.
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ginggs said:
You can deploy FDD or TDD on high or low bands, it doesn't matter.
See:
http://en.wikipedia.org/wiki/E-UTRA#Frequency_bands_and_channel_bandwidths
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Ah thanks ginggsy :-) Jeez ... have not spoken to you in ages :-) Doing good?

Everything I have read so far on TD they talk only about 2.3 and 2.6 bands so it appeared to me that you can only deploy TD in the high bands for some reason. Did not make sense to me, but that is how it seemed. Thanks for clearing that up. What do you think is better?
 
Ockie said:
Ah thanks ginggsy :-) Jeez ... have not spoken to you in ages :-) Doing good?
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Lekker, thanks. And you?
Ockie said:
Everything I have read so far on TD they talk only about 2.3 and 2.6 bands so it appeared to me that you can only deploy TD in the high bands for some reason. Did not make sense to me, but that is how it seemed.
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I think the reason is just historical. All the lower frequencies had already been allocated to the FDD, so the only available ones where in the higher bands. Similar to how we had 3G on 2100MHz first and only later on 900MHz (because 900MHz was initially allocated to GSM).
Ockie said:
What do you think is better?
Click to expand...
Well, I think technically TDD is better than FDD, but Betamax is technically better than VHS, and iBurst is technically better than 3G (WCDMA).
 
ginggs said:
Lekker, thanks. And you?

I think the reason is just historical. All the lower frequencies had already been allocated to the FDD, so the only available ones where in the higher bands. Similar to how we had 3G on 2100MHz first and only later on 900MHz (because 900MHz was initially allocated to GSM).

Well, I think technically TDD is better than FDD, but Betamax is technically better than VHS, and iBurst is technically better than 3G (WCDMA).
Click to expand...

Doing good thnanks. Having typical lazy sunday. On couch watching Terminator lol

Ja, that makes sense. But then if I was Vodacom I would have taken the refarmed spectrum and deploy TD rather than FD seeing that TD is more spectrum friendly? But I guess they also took into account that the phones out there mostly support FD only :-(


LIES!!!! ALL LIES!!! :p
 
I think one also needs to keep in mind Telkom has been pitching their LTE as a fixed mobile offering. So I don't think they really care that much about the selection of handsets that are compatible as they want you to use their dongles as sort of an ADSL alternative?
 
Ockie said:
LIES!!!! ALL LIES!!! :p
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Yeah, I should have followed up my last statement with: technical superiority isn't everything, it's the technology that ends up with the most devices that wins.
 
ginggs said:
Yeah, I should have followed up my last statement with: technical superiority isn't everything, it's the technology that ends up with the most devices that wins.
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Well, this thread is intended to delve a bit into the nether regions of "actual technical superiority" and not who wins the the popularity contest :D

With China and India and even Australia rolling out TD-LTE, there are bound to be devices and versions of the popular models like the Samsung S5 and LG G3 (I see the European version supports 2.3 band, but dont know if FD or TD) that South African networks can get to run on a potential TD roll out.
 
Good thread.. thanks Ockie

Now when you have all the answers , create a blog. It will certainly help a lot of folks.
 
Still curious about plans from other operators, Vodacom, Cell C, MTN regarding TD-LTE

Map is a bit outdated, but shows that TD-LTE is a widely adopted technology and I see no reason why our networks cant use TD-LTE together with FD-LTE.

TDDCommitmentsJuly2013.jpg
 
Ockie said:
Still curious about plans from other operators, Vodacom, Cell C, MTN regarding TD-LTE
[...] I see no reason why our networks cant use TD-LTE together with FD-LTE.
Click to expand...
There is a reason. Current devices which support both TDD and FDD simultaneously do not support the same FDD on TDD frequencies and in reverse. They do not support, as they only support combinations as defined by E-UTRA: https://en.wikipedia.org/wiki/LTE_frequency_bands#Frequency_bands_and_channel_bandwidths
The only popular frequency range which can be used for both FDD and TDD is 2600MHz - FDD band #7 and TDD band #38. Even in this case they don't use exactly the same frequencies: TDD frequency band is between FDD uplink and FDD downlink.
 
sajunky said:
There is a reason. Current devices which support both TDD and FDD simultaneously do not support the same FDD on TDD frequencies and in reverse. They do not support, as they only support combinations as defined by E-UTRA: https://en.wikipedia.org/wiki/LTE_frequency_bands#Frequency_bands_and_channel_bandwidths
The only popular frequency range which can be used for both FDD and TDD is 2600MHz - FDD band #7 and TDD band #38. Even in this case they don't use exactly the same frequencies: TDD frequency band is between FDD uplink and FDD downlink.
Click to expand...

Other networks are doing it. You have phones like my Meizu that supports both. Iphone supports both. Vodacom FD-LTE is deployed in 1800. Cant they refarm a little bit of spectrum from lets say 900band and use that to deploy TD-LTE? I am not sure if Vodacom has got access to 2300 band like Telkom does.
 
Ockie said:
Ok, sorry, had a look at that link and see that 900 band not allowed for TD-LTE. That sucks balls.
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From the look of the upcoming spectrum auction it seemed that the only unpaired spectrum allocated was Band 41 (2595-2620MHz). I think that's the biggest sign of more TD-LTE, when you don't have the two pairs and guard band needed for the uplink/downlink of FD-LTE.

I just want more local phones sold to be the models that support TD-LTE on Band 40 for Telkom. Even if you get a new Galaxy S6, it's probably one of the European models SM-920F that doesn't have it vs the India/HK ones.
 
km2 said:
From the look of the upcoming spectrum auction it seemed that the only unpaired spectrum allocated was Band 41 (2595-2620MHz). I think that's the biggest sign of more TD-LTE, when you don't have the two pairs and guard band needed for the uplink/downlink of FD-LTE.

I just want more local phones sold to be the models that support TD-LTE on Band 40 for Telkom. Even if you get a new Galaxy S6, it's probably one of the European models SM-920F that doesn't have it vs the India/HK ones.
Click to expand...

Get a Meizu. Very affordable and great phone and supports Telkom TD-LTE. Have to buy it cash from orange though. Cant get it on contract obviously
 
km2 said:
From the look of the upcoming spectrum auction it seemed that the only unpaired spectrum allocated was Band 41 (2595-2620MHz). I think that's the biggest sign of more TD-LTE, when you don't have the two pairs and guard band needed for the uplink/downlink of FD-LTE.

I just want more local phones sold to be the models that support TD-LTE on Band 40 for Telkom. Even if you get a new Galaxy S6, it's probably one of the European models SM-920F that doesn't have it vs the India/HK ones.
Click to expand...

Mmmmmm auction in the 700 band. That can be used for TD-LTE and will provide a very good range and indoor coverage. Neither the Meizu or Iphone 6s supports TD-LTE in 700mhz band.
 
Ockie said:
Get a Meizu. Very affordable and great phone and supports Telkom TD-LTE. Have to buy it cash from orange though. Cant get it on contract obviously
Click to expand...

I'm kind of tempted to shake up my Android experience with a BlackBerry Priv, so will have to see if that arrives here with B40.
 
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