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Dual Band MIMO deployment


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With Sprint's main antennas being dual band, broadcasting 1x/LTE on 800MHz and 1x/3G/LTE on PCS, what is the MIMO configuration of LTE?

 

I'm assuming that it is only 2x2 MIMO for both PCS and 800Mhz.  Are the antenna's able to handle 4x2MIMO for both 800/PCS and still broadcast 1x/3G?

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With Sprint's main antennas being dual band, broadcasting 1x/LTE on 800MHz and 1x/3G/LTE on PCS, what is the MIMO configuration of LTE?

 

I'm assuming that it is only 2x2 MIMO for both PCS and 800Mhz. Are the antenna's able to handle 4x2MIMO for both 800/PCS and still broadcast 1x/3G?

2x2 mimo for both. 2x2 mimo permanently for 800. 4x mimo possible in future for 1900 but not a priority.

 

Sent from my Nexus 5

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Thanks!

 

Is 4x2 possible on PCS if 3G or 1x gets dropped?

 

I guess Sprint has a ton of BRS, but you'd think that deploying 4x2 on their tiny 5x5MHz LTE blocks would be top priority.

Is edge-of-cell performance important on PCS LTE when you have 800? Not really.

 

 

Sent from my iPhone 6+

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2x2 mimo for both. 2x2 mimo permanently for 800. 4x mimo possible in future for 1900 but not a priority.

 

Sent from my Nexus 5

 

I think it may have been mentioned in the past, but what would need to be done to enable 4x mimo on 1900?

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Is edge-of-cell performance important on PCS LTE when you have 800? Not really.

 

 

Sent from my iPhone 6+

Edge of cell performance is important regardless of the band being used.

 

Sent from my Nexus 5 using Tapatalk

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Thanks!

 

Is 4x2 possible on PCS if 3G or 1x gets dropped?

 

I guess Sprint has a ton of BRS, but you'd think that deploying 4x2 on their tiny 5x5MHz LTE blocks would be top priority.

 

I think it may have been mentioned in the past, but what would need to be done to enable 4x mimo on 1900?

 

Antennas that support it. 

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Antennas that support it. 

 

So the current RRUs and base station equipment wouldn't have to be changed for B25? I assume these antennas are available today (if they wanted them).

 

And what prevents it on B26? Got to ask that out of curiosity...

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So the current RRUs and base station equipment wouldn't have to be changed for B25? I assume these antennas are available today (if they wanted them).

 

And what prevents it on B26? Got to ask that out of curiosity...

 

Nope. 4x MIMO capability is baked in from the getgo for Samsung, newer Ericsson RRUS31, and the non panasonic ALU based PCS RRHs. 

 

You need 4 active transmit antennas for 4x MIMO or in simplified terms each "antenna" has 1 port and on the antenna 2 ports are utilized for CDMA and 2 ports for LTE.  

 

For the low frequency band it's a physical hardware thing on both antenna and radio. It's most likely something to do with the lower band frequency itself as recent Vzw/ATT Band 13/12/17 rrus are 2T2R / 2x MIMO as well including tmobile utilizing off the shelf RRUS11 B12s and some other 2x2 MIMO rru for nokia land. 

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Nope. 4x MIMO capability is baked in from the getgo for Samsung, newer Ericsson RRUS31, and the non panasonic ALU based PCS RRHs. 

 

Since I live in ALU land I'll need to look through the spotting thread to figure out the non panasonic equipment. I think they are fairly well mixed around here.

 

 

You need 4 active transmit antennas for 4x MIMO or in simplified terms each "antenna" has 1 port and on the antenna 2 ports are utilized for CDMA and 2 ports for LTE.  

 

If I understand it correctly, an antenna can transmit (and receive) multiple carriers. It is an RRU limitation that results in the high capacity sites correct?

 

 

For the low frequency band it's a physical hardware thing on both antenna and radio. It's most likely something to do with the lower band frequency itself as recent Vzw/ATT Band 13/12/17 rrus are 2T2R / 2x MIMO as well including tmobile utilizing off the shelf RRUS11 B12s and some other 2x2 MIMO rru for nokia land. 

 

Got it. Thanks. :tu:

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My understanding is that going from 2T to 4T effectively doubles the spectrum bandwidth. So 5MHz on 2T is ~38Mbps, 5MHz on 4T is ~76Mbps.

4 antennas on the UE are required in order to get double the potential speeds.

 

Sent from my Nexus 5

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For the low frequency band it's a physical hardware thing on both antenna and radio. It's most likely something to do with the lower band frequency itself...

 

Likely, too big.  The lower the frequency, the longer the wavelength, the larger the antenna.  A 4T4R 800 MHz antenna might be the size of a refrigerator.

 

AJ

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Likely, too big. The lower the frequency, the longer the wavelength, the larger the antenna. A 4T4R 800 MHz antenna might be the size of a refrigerator.

 

AJ

AJ, that's a massive antenna:

f603b445032f0c0b6ee680a629a8dabb.jpg

 

 

Sent from my iPhone 6+

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  • 3 weeks later...

Does anyone have a time-line on when MIMO/8T8R will be turned on? I'm much more excited about this than carrier aggregation.

If sprint 2.5 sites are online then they're already running 8t8r since 8T8R is the description of the antennas themselves (8 transmit / 8 receive antennas via 8 jumper cables to the radio).

 

Initially they are running 2x2 dynamic open loop mimo (tm3). activation of second carrier changes this to 4x2 mimo using tm8 beamforming.

 

Sent from my Nexus 5

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4x mimo possible in future for 1900 but not a priority.

Some markets (particularly in Ericsson territory) saw quite a few 2.5 permits filed 2H 2014 which were approved but never actually built out. Many of those have been rapidly re-filed in 1H 2015 with the addition of RRUS 31 swapout and second set of PCS antennas. The additional antennas don't really make sense as being necessary for a second carrier, nor do they make sense as being for >3-sector sites with having the same azimuth.

 

They only really make sense as being either for higher order MIMO or for getting more antenna elements in the air to improve the B25 uplink when inter-carrier aggregation launches.

 

fm2deWp.png

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