maximum speeds attainable?

[Colton123]

So which category is the current 2x2 devices? And which category is 4x2 devices?

 

Is the 82.3Mbps download rate for configuration 1 with 20Mhz channel size for a device with just 2x2 or a device with 1x1? 

 

Very confused is the tower is 8x8 but the UE's are only 2x2 or 4x2 today, then what are max speeds obtainable. Assume only connected to 1 20Mhz Band 41 TDD channel.

[WiWavelength]

There is no 4x4 or 8x8 UE available.

 

Next step up is 4x4. Right now it's 2x2/4x2.

 

And until several 4x4 downlink MIMO handsets are announced, we should not anticipate many, if any.  At the handset level, 4x4 downlink MIMO basically is vaporware.

 

AJ

[lilotimz]

So which category is the current 2x2 devices? And which category is 4x2 devices?

 

Is the 82.3Mbps download rate for configuration 1 with 20Mhz channel size for a device with just 2x2 or a device with 1x1?

 

Very confused is the tower is 8x8 but the UE's are only 2x2 or 4x2 today, then what are max speeds obtainable. Assume only connected to 1 20Mhz Band 41 TDD channel.

Category 3,4,6,9, 10

 

4x2 Mimo is eNB antenna configuration. Instead of two Tx streams aimed at the UE, there are 4 which improves SINR, edge of cell connectivity, and stability of speeds at all signal levels.

 

The antennas and radios are 8T8R meaning there's 8 Tx/Rx antennas active to broadcast the connection. For speeds Look at the chart. It lists the theoretical speeds for every LTE MHz configuration.

[Colton123]

Category 3,4,6,9, 10

 

4x2 Mimo is eNB antenna configuration. Instead of two Tx streams aimed at the UE, there are 4 which improves SINR, edge of cell connectivity, and stability of speeds at all signal levels.

 

The antennas and radios are 8T8R meaning there's 8 Tx/Rx antennas active to broadcast the connection. For speeds Look at the chart. It lists the theoretical speeds for every LTE MHz configuration.

I did look at the chart, but what is not clear to me is the chart showing 1 stream, 2, or 4.

 

I read this article, http://www.ijitee.org/attachments/File/v3i12/L16590531214.pdf. Using 2 streams it get the 82Mbps number you mentioned, but the calculation shows 2 streams. I assume this means a 2x1 UE device? http://www.ijitee.org/attachments/File/v3i12/L16590531214.pdf

 

So with a 4x2 UE device can I double the number you have in your chart? 

[lilotimz]

I did look at the chart, but what is not clear to me is the chart showing 1 stream, 2, or 4.

 

I read this article, http://www.ijitee.org/attachments/File/v3i12/L16590531214.pdf. Using 2 streams it get the 82Mbps number you mentioned, but the calculation shows 2 streams. I assume this means a 2x1 UE device? http://www.ijitee.org/attachments/File/v3i12/L16590531214.pdf

 

So with a 4x2 UE device can I double the number you have in your chart? 

No. 

 

4x2 is a eNB enhancement. To double speeds, 4x4 MIMO must be utilized on both the eNB and UE.  Devices available today are only capable of 2x2 UE. 

 

4x4 MIMO as in 4 Tx streams from eNB going to UE and 4 Tx streams going back to eNB from UE. 

[Colton123]

No. 

 

4x2 is a eNB enhancement. To double speeds, 4x4 MIMO must be utilized on both the eNB and UE.  Devices available today are only capable of 2x2 UE. 

 

4x4 MIMO as in 4 Tx streams from eNB going to UE and 4 Tx streams going back to eNB from UE. 

 I was not understanding how that makes any sense, but now I read that the original OP was talking about the max upload speeds, and I was talking about download speeds. 

 

So just to confirm, the best UE devices today are 4X2 right? Which UE category device is that?

 

A 4x2 UE device can obtain double the download speeds of a 2x2 UE device, but has exactly the same upload speed right?

 

So using one 20Mhz wide TTD-LTE channel, what is the max download speed a 4x2 UE device can obtain based on sprint's 1 configuration? I assume its 164.6Mbps? That is 82.3Mbps times 2. 

 

I know there is carrier aggregation so that confuses things even more. But lets assume Sprint only have one 20Mhz wide TTD-LTE channel. 

[lilotimz]

 I was not understanding how that makes any sense, but now I read that the original OP was talking about the max upload speeds, and I was talking about download speeds. 

 

So just to confirm, the best UE devices today are 4X2 right? Which UE category device is that?

 

A 4x2 UE device can obtain double the download speeds of a 2x2 UE device, but has exactly the same upload speed right?

 

So using one 20Mhz wide TTD-LTE channel, what is the max download speed a 4x2 UE device can obtain based on sprint's 1 configuration? I assume its 164.6Mbps? That is 82.3Mbps times 2. 

 

I know there is carrier aggregation so that confuses things even more. But lets assume Sprint only have one 20Mhz wide TTD-LTE channel. 

 

No. 

 

4x2 MIMO is purely a eNB enhancement. In a 4x2 MIMO setup it has 4 Tx from the antennas on the cell site and 2 Rx streams since the current available UEs only talk in 2x2 MIMO. 

 

To receive DOUBLE the bandwidth with the same spectrum, 4x4 MIMO must be utilized on both eNB and UE. 4x2 MIMO only increases the signal quality NOT speeds. 

 

4x4 MIMO on on most UEs are not expected til next year with the new category 12/13 Qualcaum Modems. 

[Flompholph]

I think you are confusing tower MIMO and UE MIMO. All LTE devices are 2x2. Some towers are 4x2 MIMO meaning two phone each could be using 2x2 MIMO. The tower and the phone both have to be 4x4 capability to double the speed (4x4 means 4 spatial streams from the tower to 4 antennas on the phone.)

[Colton123]

Yes, I too think I was a little confused.

 

So, just to confirm, for tower MIMO Sprint is using 8x8 on the tower right?

 

For the UE, what is confusing me is you say most of the UE devices out there are 2x2 MIMO today. Based on what I have seen however they can only use 1 stream on the upload side, so really are these devices 2x1 devices? Two streams for download and 1 stream for upload? 

[Flompholph]

When talking about MIMO you are talking only one direction So your device is n x 2 for download and 1 x j for the upload. n is eqaul to or less than the number of antennas on the site. j is the number of antennas on the site used to listen.

 

Sprint B41 is 8t8r 8 transmit and 8 receive. They plan on 2 different 4x2 chains for now they could support 8x2 but they don't. There are no 4x4 devices yet so no plan on using 4x4 chains yet.

[Colton123]

Understood. 

 

Why are they calling UE devices 2x2, 4x2, or 4x4 then if at max only 1 stream can be used in the upload side? So really these devices are 2x1, 2x1, or 4x1 right? 

[Flompholph]

Understood. 

 

Why are they calling UE devices 2x2, 4x2, or 4x4 then if at max only 1 stream can be used in the upload side? So really these devices are 2x1, 2x1, or 4x1 right?

Because the UE is 2x2, 4x2, or 4x4 on the download side of the UE. People don't talk about the 1x? upload side because no one really cares about upload that much. If people cared about upload they would say "my 2x2 SU-MIMO down and 1x1 SU-MIMO up device sucks on the upload. It is always half my download speeds on an empty site."

[Colton123]

Because the UE is 2x2, 4x2, or 4x4 on the download side of the UE. People don't talk about the 1x? upload side because no one really cares about upload that much. If people cared about upload they would say "my 2x2 SU-MIMO down and 1x1 SU-MIMO up device sucks on the upload. It is always half my download speeds on an empty site."

But isn't the A X B of the UE in MIMO, on the A is the number of receive antennas, and the B the number or send antennas? Does a 2x2 UE device really have 2 antennas used for uploading data back to the cell tower? 

[Flompholph]

But isn't the A X B of the UE in MIMO, on the A is the number of receive antennas, and the B the number or send antennas? Does a 2x2 UE device really have 2 antennas used for uploading data back to the cell tower?

No that is what we were trying to tell you A is one point such as the tower and B is another point such as the UE.

[WiWavelength]

We need not overcomplicate this.  For MIMO, forget about uplink.  Uplink MIMO may not happen for a good while.

 

So, it is downlink MIMO.  And 2x2 downlink MIMO means two separate downlink Tx antennas at the base station and two separate downlink Rx antennas at the handset.

 

Simple as that.

 

AJ

[Colton123]

We need not overcomplicate this.  For MIMO, forget about uplink.  Uplink MIMO may not happen for a good while.

 

So, it is downlink MIMO.  And 2x2 downlink MIMO means two separate downlink Tx antennas at the base station and two separate downlink Rx antennas at the handset.

 

Simple as that.

 

AJ

AJ, thank you so much for explaining this. I now understand what they mean!

 

So, CAT 5 devices have 4x4 MIMO right? So those devices should be able to double the downlink speed right? Hence why CAT5 UE devices are rated at 300Mbps (for LTE FDD), but CAT 4 are only rated for 150.8Mbps since they only support 2x2.  

 

Is this double the download speed done by:

1. Taking a single 20Mhz wide TTD-LTE channel, and sending 4 streams of it to the end user.

2. Taking two separate 20Mhz wide TTD-LTE channels, doing carrier aggregation for a total of 40Mhz, and sending 2 streams of the primary 20Mhz wide channel, and 2 streams of the secondary 20Mhz wide channel? 

[Flompholph]

So, CAT 5 devices have 4x4 MIMO right? So those devices should be able to double the downlink speed right? Hence why CAT5 UE devices are rated at 300Mbps (for LTE FDD), but CAT 4 are only rated for 150.8Mbps since they only support 2x2.

Upto 4x4 and yes that is the difference but show me a Cat 5 device on sprint.

 

 

 

Is this double the download speed done by:

1. Taking a single 20Mhz wide TTD-LTE channel, and sending 4 streams of it to the end user.

2. Taking two separate 20Mhz wide TTD-LTE channels, doing carrier aggregation for a total of 40Mhz, and sending 2 streams of the primary 20Mhz wide channel, and 2 streams of the secondary 20Mhz wide channel?

It is number 1. MIMO reuses spectrum and carrier aggregation adds a different block of spectrum. A device can be 4x4 MIMO and CA two 20Mhz blocks for a total of 8 spacial streams but that is 2+ years away only in labs testing now.

[Colton123]

I assume there are no Cat 5 devices on Sprint at this time?

 

Aren't the latest smartphones like the Iphone 6s and Samsung S6 CAT 6 devices? Looking at the LTE UE chart, it shows that CAT 6 devices can had 2 or 4 Maximum number of supported layers for spatial multiplexing in DL. Do all the more advanced smartphones just have 2 and not 4?

 

What about something like the Note 5 which is a CAT 9 device? 

[Colton123]

It is number 1. MIMO reuses spectrum and carrier aggregation adds a different block of spectrum. A device can be 4x4 MIMO and CA two 20Mhz blocks for a total of 8 spacial streams but that is 2+ years away only in labs testing now.

 

Thanks! What about the case with carrier aggregation of two separate 20Mhz blocks, and 2x2 on each block for a total of 4 streams? Are there sprint devices that can do this today? What LTE UE Category are those kind of devices? 

[NYC126]

This is what Sprint planned in 2014 for 2015 and beyond:

3x channel CA at 2x2 Mimo 330 megabits down

3x CA at 4x4 MIMO 660 megabits down

3x CA at 8x8 MIMO 1320 aka gigabits

 

The so called magical 8T8R 2.5gz anntenas that magentans love to mock are network future proof and they are actually for when 8x8 MIMO becomes available years down the road.

http://www.lightreading.com/mobile/4g-lte/sprint-promises-180mbit-s-peaks-in-2015/d/d-id/709518

[Flompholph]

Thanks! What about the case with carrier aggregation of two separate 20Mhz blocks, and 2x2 on each block for a total of 4 streams? Are there sprint devices that can do this today? What LTE UE Category are those kind of devices?

Yes, most newer flagship phones. Cat 6

 

 

This is what Sprint planned in 2014 for 2015 and beyond:

3x channel CA at 2x2 Mimo 330 megabits down

3x CA at 4x4 MIMO 660 megabits down

3x CA at 8x8 MIMO 1320 aka gigabits

 

The so called magical 8T8R 2.5gz anntenas that magentans love to mock are network future proof and they are actually for when 8x8 MIMO becomes available years down the road.

http://www.lightreading.com/mobile/4g-lte/sprint-promises-180mbit-s-peaks-in-2015/d/d-id/709518

That is all PR. No planned modems can handle that yet meaning many many years down the road. And things have changed such as a max of 85Mbps per 2x2 20MHz block. Hopefully they increase the QAM so for those times you are near the antenna you get higher speeds.

[Colton123]

This is what Sprint planned in 2014 for 2015 and beyond:

3x channel CA at 2x2 Mimo 330 megabits down

3x CA at 4x4 MIMO 660 megabits down

3x CA at 8x8 MIMO 1320 aka gigabits

 

The so called magical 8T8R 2.5gz anntenas that magentans love to mock are network future proof and they are actually for when 8x8 MIMO becomes available years down the road.

http://www.lightreading.com/mobile/4g-lte/sprint-promises-180mbit-s-peaks-in-2015/d/d-id/709518

Based on those numbers, its looks like the are quoting about 110Mbps download bases on a single CA 2x2 right? I guess these slides are based on using LTE TTD Configration 2 which has a max of 112.5Mbps which is darn close to 110Mbps quoted right?

 

As mentioned, Sprint uses configuration 1 right? 

[WiWavelength]

Based on those numbers, its looks like the are quoting about 110Mbps download bases on a single CA 2x2 right? 

 

There is no such thing as "single CA."  That would be 1x CA, which is not CA.

 

AJ

[Colton123]

There is no such thing as "single CA."  That would be 1x CA, which is not CA.

 

AJ

Yep, that is what I meant sorry for throwing the CA in there  

 

But that PR numbers are based on 110Mbps per 20Mhz right, which is config 2 not 1. So the PR numbers are right if Sprint were using config 2 which they are not. 

[WiWavelength]

Yep, that is what I meant sorry for throwing the CA in there

 

But that PR numbers are based on 110Mbps per 20Mhz right, which is config 2 not 1. So the PR numbers are right if Sprint were using config 2 which they are not. 

 

I have no clear idea.  It could be Configuration 2.  Or the cited 110 Mbps figure could be Configuration 1 -- but with 256 QAM.  The difference between 256 QAM and 64 QAM is eight bits per symbol vs six bits per symbol.

 

8 ÷ 6 = 1.33 × 82.3 = 109.7

 

AJ