TD-LTE vs FD-LTE

Ockie said:
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.
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I think that's pretty unlikely though. Look at how it's described "2 x 20MHz (703-723MHz/ 758-778MHz)" by ICASA. That perfectly matches an FD-LTE type auction with the frequencies for uplink/downlink (i.e. Band 28), it's a mighty weird one to be used for TD-LTE B44.
 
km2 said:
I think that's pretty unlikely though. Look at how it's described "2 x 20MHz (703-723MHz/ 758-778MHz)" by ICASA. That perfectly matches an FD-LTE type auction with the frequencies for uplink/downlink (i.e. Band 28), it's a mighty weird one to be used for TD-LTE B44.
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But with TD you can use one pair for uplink and downlink. More efficient. More people the tower.
 
I personally think the world made a mistake. TD should be the tech of choice when it comes to LTE I believe. I wish Jannie would comment here. I would love to hear his thoughts on these two different iterations of LTE
 
Ockie said:
I personally think the world made a mistake. TD should be the tech of choice when it comes to LTE I believe. I wish Jannie would comment here. I would love to hear his thoughts on these two different iterations of LTE
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Look I personally like TD-LTE just in terms of "technical feel". I like the idea of a big 100MHz chunk that can get repurposed for uplink/downlink based on network needs, vs these fixed chunks.

But I worry with any time division system when your cell size starts to get large, and which it will because that's the whole point of deploying at a low frequency like 700MHz. You don't have the frequency gap to act as your guard band that separates the uplink/download, you have the time gap, and the larger the cell is the longer you have to wait for the transmission to finish propagating to all clients in the cell, and the longer you have to wait between switching between downlink and uplink modes. That's going to hammer your efficiency.

Some more info on it.
 
km2 said:
Look I personally like TD-LTE just in terms of "technical feel". I like the idea of a big 100MHz chunk that can get repurposed for uplink/downlink based on network needs, vs these fixed chunks.

But I worry with any time division system when your cell size starts to get large, and which it will because that's the whole point of deploying at a low frequency like 700MHz. You don't have the frequency gap to act as your guard band that separates the uplink/download, you have the time gap, and the larger the cell is the longer you have to wait for the transmission to finish propagating to all clients in the cell, and the longer you have to wait between switching between downlink and uplink modes. That's going to hammer your efficiency.

Some more info on it.
Click to expand...

Very interesting read. Thank you. Gosh ... it is complicated. I pretty much thought that well, TD uses the same spectrum to download and upload using time division to accomplish this, whereas FD needs to strands of spectrum to do the same, hence less spectrum efficiency. Now I dont know what to think. urg.
 
TD-LTE is massive in China.

And you are right it is technically less "wasteful" of spectrum since seperate uplink/downlink channels aren't required. It doesn't however provide as good a coverage area (it can, but under pressure the cells shrink a bit).
 
TheRoDent said:
TD-LTE is massive in China.

And you are right it is technically less "wasteful" of spectrum since seperate uplink/downlink channels aren't required. It doesn't however provide as good a coverage area (it can, but under pressure the cells shrink a bit).
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I wouldn't take China's usage of it as being for purely technical reasons though. I think they don't want to be at the mercy of Qualcomm and its massive FD-LTE patent arsenal, when you can instead have Huawei as the big dog in the TD-LTE space.
 
km2 said:
I wouldn't take China's usage of it as being for purely technical reasons though. I think they don't want to be at the mercy of Qualcomm and its massive FD-LTE patent arsenal, when you can instead have Huawei as the big dog in the TD-LTE space.
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Co-developed by Qualcomm, Samsung, Huawei and lots of other vendors. Samsung is supposedly the biggest LTE patent holder.

TD-LTE has essentially taken over most of the old Wimax spectrum.
 
TheRoDent said:
TD-LTE is massive in China.

And you are right it is technically less "wasteful" of spectrum since seperate uplink/downlink channels aren't required. It doesn't however provide as good a coverage area (it can, but under pressure the cells shrink a bit).
Click to expand...

In Urban areas this could be big., even if the cell shrings a lot. I wonder if Vodacom for example could do TD-LTE on their existing towers. They already have a dense network in Gauteng for example, so this should not provide a issue. Question is, do they have the right spectrum to deploy TD-LTE. To my knowledge, only Telkom has access to 2300 band. :mad:
 
My LG G3 Dual Sim also does TDD 2300MHz in the one sim slot.

Don't know about other LG models.
 
Two aspects drive this;

1. What was assigned by the regulator. Remember - outside of Telkom's 60MHz in 2.3 - no actual spectrum was assigned for LTE in South Africa. This forced the mobile operators to re-farm their paired 2G/3G spectrum.

2. Device support. TD-LTE and, more importantly, FDD/TD aggregation is only beginning to happen now.

The future is going to look very different with new devices being able to aggregate (combine) various bands and modulation systems into a single connection.

A few months ago we aggregated Wi-Fi with our (puny, in comparison) LTE allocation and got 500Mb/s!
 
jannievanzyl said:
Two aspects drive this;

1. What was assigned by the regulator. Remember - outside of Telkom's 60MHz in 2.3 - no actual spectrum was assigned for LTE in South Africa. This forced the mobile operators to re-farm their paired 2G/3G spectrum.

2. Device support. TD-LTE and, more importantly, FDD/TD aggregation is only beginning to happen now.

The future is going to look very different with new devices being able to aggregate (combine) various bands and modulation systems into a single connection.

A few months ago we aggregated Wi-Fi with our (puny, in comparison) LTE allocation and got 500Mb/s!
Click to expand...

Thank you for giving input Jannie.

Jannie, with TD becoming more available in handsets and routers, is Vodacom looking at all @ TD?
 
Ockie said:
I personally think the world made a mistake. TD should be the tech of choice when it comes to LTE I believe. I wish Jannie would comment here. I would love to hear his thoughts on these two different iterations of LTE
Click to expand...
FDD is a natural migration path from the old GSM/WCDMA technologies (like 3G/HSPA).
TDD is a natural migration path from CDMA technologies (like EvDO).
As for the future, it will be easier for FDD, sorry for quoting Jannie. :)
jannievanzyl said:
The future is going to look very different with new devices being able to aggregate (combine) various bands and modulation systems into a single connection.
Click to expand...
 
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