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What's the power consumption of a cell site?


burnout8488
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This has always piqued my curiosity. Say it's just a run of the mill Sprint site - 3 panels, 6 RRUs. (Not including the computers and equipment that are in the "huts" at the base of the tower) Is it like running 3-4 120v window air conditioners in my home? Or way, way above that? I've got no clue what kind of juice it takes to broadcast cellular signals to an entire town. 

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This has always piqued my curiosity. Say it's just a run of the mill Sprint site - 3 panels, 6 RRUs. (Not including the computers and equipment that are in the "huts" at the base of the tower) Is it like running 3-4 120v window air conditioners in my home? Or way, way above that? I've got no clue what kind of juice it takes to broadcast cellular signals to an entire town. 

Well, the backup generators are sized 20-40kw. It depends on how many bands and how wide the spectrum is, the number of panels, how old the base station equipment is.

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This has always piqued my curiosity. Say it's just a run of the mill Sprint site - 3 panels, 6 RRUs. (Not including the computers and equipment that are in the "huts" at the base of the tower)

 

What I find interesting is that most Sprint base station equipment is relatively small in size and out in the open.  At least in this area, AT&T still uses those air conditioned, composite material huts for nearly all sites, even for new build sites.  Those huts cannot be as energy efficient, so I wonder why AT&T still uses them.  Since AT&T (nee SBC) is the RBOC here, maybe they also run DSL nodes out of them.

 

AJ

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What I find interesting is that most Sprint base station equipment is relatively small in size and out in the open.  At least in this area, AT&T still uses those air conditioned, composite material huts for nearly all sites, even for new build sites.  Those huts cannot be as energy efficient, so I wonder why AT&T still uses them.  Since AT&T (nee SBC) is the RBOC here, maybe they also run DSL nodes out of them.

 

AJ

 

Surely they would be better insulated and thus more energy-efficient when it comes to air conditioning than a thin metal cabinet?

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What I find interesting is that most Sprint base station equipment is relatively small in size and out in the open.  At least in this area, AT&T still uses those air conditioned, composite material huts for nearly all sites, even for new build sites.  Those huts cannot be as energy efficient, so I wonder why AT&T still uses them.  Since AT&T (nee SBC) is the RBOC here, maybe they also run DSL nodes out of them.

 

AJ

 

Have you ever seen an AT&T squid?  That's why they use the hut!  I wish I could track down a pic.  The install takes up the whole hut.

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What air conditioning?  Some of the Sprint base stations I have seen use ambient cooling.

 

AJ

 

That was my point. An air conditioner in a thick hut won't have to run 24/7, but ambient cooling on thin metal boxes in a hot climate will.

 

EDIT: I'm going under the assumption that when you say ambient cooling, you mean fans blowing, and that you would have said passive cooling otherwise.

 

Who knows what they have inside though?

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That was my point. An air conditioner in a thick hut won't have to run 24/7, but ambient cooling on thin metal boxes in a hot climate will.

 

EDIT: I'm going under the assumption that when you say ambient cooling, you mean fans blowing, and that you would have said passive cooling otherwise.

 

Who knows what they have inside though?

Well designed placement of the heat generating equipment in the cabinet and well placed fans to move the heat out.

Some of the equipment in the cabinets generate more heat that other pieces of equipment. With the radios out of the cabinets and up with the antennas, much of the heat is generated and dissipated there.

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That was my point. An air conditioner in a thick hut won't have to run 24/7, but ambient cooling on thin metal boxes in a hot climate will.

Doubtful. Outside of extreme climates, the issue is not one of external temperature.  The issue is internal temperature.  The equipment itself generates waste heat.  That requires cooling.  Metal is a good conductor for wicking away waste heat.  A hut, on the other hand, insulates and contains that internal waste heat.

 

As an experiment, try running an audio power amp 24/7 out in the open versus inside an insulated cooler.  Which one needs the air conditioner?

 

EDIT: I'm going under the assumption that when you say ambient cooling, you mean fans blowing, and that you would have said passive cooling otherwise.

 

Ambient cooling could be passive or forced air -- it covers both bases.

 

AJ

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Well designed placement of the heat generating equipment in the cabinet and well placed fans to move the heat out.

Some of the equipment in the cabinets generate more heat that other pieces of equipment. With the radios out of the cabinets and up with the antennas, much of the heat is generated and dissipated there.

Yes, the RF amps generate most of the heat and consume most of the power. A single antenna sector might radiate 50/MHz. If we assume that the sector is fully loaded and is using a 20MHz FDD channel then it's using at the max 50x20MHz. Now a wideband RF amps might be 50% efficient if at that. Most of the time it is 20-30%. If at 33%, then each antenna/rf amp will be consuming 3000 Watts. so for a three sector site, that will be 9-10,000 Watts. That does not include any of the other equipment.

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Yes, the RF amps generate most of the heat and consume most of the power. A single antenna sector might radiate 50/MHz. If we assume that the sector is fully loaded and is using a 20MHz FDD channel then it's using at the max 50x20MHz. Now a wideband RF amps might be 50% efficient if at that. Most of the time it is 20-30%. If at 33%, then each antenna/rf amp will be consuming 3000 Watts. so for a three sector site, that will be 9-10,000 Watts. That does not include any of the other equipment.

 

Oh, if you are using air conditioning to cool any of the equipment you have to double the power budget...

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