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Reducing RAN Energy Costs

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Macro site cooling is becoming an issue moving ahead. As it turns out, energy is the real issue. Utility bills have become a huge expense. Why? Did you look at your own bill lately? Mine shot up over 20% over the past 2 years, and I don’t see it going down. Think about that.  I am just paying for my home, no data room, no radios, and normal heating and cooling. 

At a site, there is so much equipment that sucks down huge amounts of electricity. A macro site has more to do than ever before. I think people outside the industry imagine we just update the radio or add a new radio, it’s way more than that. There is more equipment at a site than ever before, using more channels, spectrum, and bandwidth at all the carrier sites. More than ever in telecom history. 

While 5G equipment is more efficient, the additional equipment uses more power. The equipment uses less energy per bit but the bandwidth went way up, from 20MHz/site to over 100MHz/site at major carriers’ sites. More bits mean more energy, and that means higher electric bills. 

The OEMs have done a good job at getting the radios more efficient, but they need electricity to do all the functions they’re asked to do.

The two critical things at every site are the utilities – power and backhaul.  

Also, think about what equipment is at a macro site. It has radios, BBUs, rectifiers, routers, switches, possibly servers, muxes, fans, air conditioners, cameras, lights, telco interfaces, and security systems. Even more which I am missing.

In other words, there is a lot of crap to power in a macro site. 

Let’s break down why power matters;

  • Carriers usually have a lot of Macro sites, according to Steel in the Air:
  • Now, let’s look at what the assumed average annual macro site electric bill was, according to Lucas Mearian from Computer World, in 2022,
    • Urban sites used about 57.5 MWH costing $7,877.50 per site,
    • Suburban sites used about 46.25 MWH costing about $6,336.25 per site,
    • Rural sites used about 12.5 MWH costing about $1,712.50 per site,
  • Now, let’s make up a guesstimate of the ratio and believe me this is all hypothetical,
    • 45% Urban,
    • 35% Suburban,
    • 20% Rural,
  • Now, let’s look at the averages I put together down below, and remember, I am making most of this up based on the articles referenced above. Actually, I would bet it’s much higher now. I remember in early 2022 my utility bill shot up. The actual costs shot up so a comparable bill from the prior year was 10% less. So imagine that attached to the numbers below. 

Let that sink in for a few moments. Imagine the electric bills on all those sites, Imagine your collective utility bill is over $400M every year! Now, imagine that goes up 10%, which is $40M for every year after that. Imagine paying hundreds of companies across the US and not being able to get any type of bulk discount because the sites are so spread out, not in one large facility like a manufacturer or warehouse could do. 

Now, imagine you could save 20%, that would be over $80M/year. Let that sink in. This is an annual savings, so over 5 years that becomes a $100M savings. 

FYI – utility bills do not go down. Have yours gone down?

What am I missing? Well, utility bills shot up in 2022 and 2023, adding 5G and networking equipment to sites added to the utility cost. I didn’t take any data centers or small cells into consideration. The real number that carriers pay for utility is probably way higher! Probably 40% to 80% higher if I had to guess. 

In today’s world, all we need is another thing to maintain. However, we’re going to take a look at liquid cooling in networks and at tower sites. I want to go over how this may help shape the networking industry moving forward.

Can we make the radios more efficient?

To be honest, the major OEMs have done a good job making their equipment energy-efficient, although some carriers may disagree. The equipment is always getting more and more efficient.

The OEMs also have another trick up their sleeves, they realized that by using intelligence, specifically ML and AI, they could lower power or even shut down channels or sectors during slow periods saving power at multiple sites across the country. 

Each OEM seems to have a strategy. 

They have more control over software than they ever did. That means that the radios and their controllers are smarter than they ever were before. Everything is monitored more or less in real time. Software and automation have gotten smart. 

Let me give you a high level about how this helps. Using ML and AI we track usage at a site and build models around the busy hours and the slow hours. When a site is very slow or not used at all, it can do a few things.

  • Reduce power, if it doesn’t need high power, why use it?
  • Shut down carriers, if they’re not needed, why use them?
  • Shut down sectors, or put them into a “sleep” mode.

In other words, the radios are learning to be more efficient with their power. They are becoming smarter. This means that if they can accurately track usage, they can use less power in the downtime. 

Think of your home, I would bet many of you have smart thermostats. When you go to bed at night you may set the thermostat to use less cooling or heating. You may have smart lighting control the lights on/off times. You’re saving power, good for you! 

Smart, right?

OEMs mention that the radios are designed to be more efficient. That’s nice to hear, but it’s an expectation that equipment has evolved from the previous generation. They can pack more features into one unit and make it more energy-efficient. In today’s world, that is an expectation with any high-tech equipment. 

The one thing I will talk about further down is how Nokia is offering liquid-cooled equipment for the cell site. It’s pretty cool. 

What can the carriers do?

Looking at it from a carrier’s perspective is different from most OEMs. They have to look at each site holistically like they do when they pay rent. That’s why shelters were replaced by cabinets. Smaller ground footprints meant less rent money. More bands in one radio and antenna means less tower rent.

Let’s look at the site energy holistically and then look for reductions. This means to break out each item that uses serious energy. Let’s look at the list below.

  • Radios,
  • BBUs,
  • Networking gear,
  • Telco and fiber equipment,
  • Cooling and heating systems,
  • Rectifiers,
  • Fans,
  • Battery charging systems (which might be in the rectifiers, sorry for being redundant),
  • Lighting,
  • Security systems like cameras, sensors, alarms, and so on,
  • Any other item using power, 

All of this adds up. 

For utility and maintenance, there was one thing that had to go, radio fans. Fans are an inductive load using energy and would fail often. When the radio is on the tower, you need a crew to replace the radio unit just because a fan failed. In the old days, when radio fans failed then they would soon overheat. Radio fans are minimized in radios today. The OEMs did a good job minimizing the number of fans.

Cooling is a site issue. Why? AC units use a lot of power, tend to run all summer long, and fail  from time to time. At least that was my experience. AC units also need to be maintained which adds cost because a different skill set was required to maintain and repair. Normal site techs didn’t normally do this. 

Cooling units had to be reduced. Air conditioning (AC) units add a lot of cost for many reasons, including maintenance and utility bills. If these units can be reduced or removed, then the carriers save in multiple ways. Many cabinets are working to use airflow for cooling. They use sun shields to reduce solar heating. Cabinet fans are used to reduce added AC costs,  (even after what I said above). Fans are cheaper than AC units. Anyone can replace a fan. 

As for the radios, this is where we leverage the OEM’s smart savings features. This is already happening, but as I mentioned before, implementation takes time. These features need to be tested and go through acceptance. That is never quick in the carriers’ world.  

What if we increase revenue per site?

One thing to look at is how each site claims revenue, to make the energy per bit more efficient. We want to make each site a profit center. Thank you FWA.

When the carriers started offering FWA, the suburban (and maybe rural) sites became profit centers and not fill sites. Suddenly, more sites became profitable.

Even in urban areas where sites may be slammed during the day can now offer home internet at night making each site more profitable by providing connections all day and night.  

By adding more subs and new services at each site, the sites may use more energy, but they are making more money. This means each site can provide more value to the carrier. 

This is an upside to FWA. All those rural and suburban sites that used to just handle a few subs when they traveled into that particular coverage can now provide internet access to the homes surrounding it. 

Can we use alternative power solutions?

People think that renewable power is the end-all solution when in reality it creates a new series of problems. 

People think you can just add solar and wind then you’ll be fine. That is so far from the truth.

I have looked into this and it’s not as easy as you think. Remember that a macro site requires a lot of power. Especially in the US. The power needed to make the equipment run is usually too much for a standard renewable power system. 

Let’s look at what’s needed.

If you go solar, you need a lot of real estate to get the power you need. That’s why in an urban setting, solar is next to impossible unless you have a parking lot or an entire roof to spread out solar panels. You need a lot of room to put panels out.

If you add wind, the same thing only now you’re going up and out. Wind turbines need space and they do fail from time to time. They also require maintenance.

Now, with all the other issues listed above, you need to engineer for those services. Sunlight in some places is not as abundant as in others. The wind isn’t always blowing. Planning and engineering matter.

Finally, this is the elephant in the room. You will need batteries, lots and lots of batteries to sustain the power once you capture it. Even if you have power, you need batteries. If you rely on sustainable power, you need many times the batteries a normal site needs. That means more real estate is required inside the shelter or on the ground. You also need all the equipment to support it. 

Batteries are an issue for so many reasons, and not just because of what they can do to the environment. There is the ethical sourcing of batteries. Some supplies come from the Congo in Africa and the work conditions there are just horrible. I would recommend you read the book “Cobalt Red” by Siddharth Kara, it was enlightening to me. We are all moving to lithium-ion batteries, and the electric vehicle situation made them even more of a priority. Also, with those batteries, the energy to make them is ridiculously high causing more of a carbon footprint than most gas vehicles cause for a long time.

It’s not a solution for most stand-alone sites, at least not in the States. It could be a backup or something to lower the electric bill, but at what cost? The more ground cover you need, the more rent you pay. All the other stuff is required but it’s just not a great model in the US.

Maybe for small cells, but even then you need batteries to keep it on air. Batteries are heavy and require room, which if it’s a small cell you may not have it.

So as you can see, sustainable power sounds like a great idea, but in reality, you have to take it for what it is, a somewhat viable backup solution unless, or use it if it’s the only thing you have available. Then you have to make it work.

What is Net Zero?

I hear bigger companies talking about Net Zero often like it will save the world. Maybe it will. So, what is Net Zero?

I have looked into this to see what it is and an article that I could follow was found here. It’s by Vaishali Deshmukh, called “Net Zero: A Short History”. She says that Net Zero is, “Being at net zero emissions refers to a point where the GHG emissions released by humans into the air are balanced by the emissions removed from the air.” 

What does that mean? Well, GHG means Greenhouse Gases. It’s complicated, but the link explains it. For this article let’s just say it’s Carbon Dioxide and other gasses. It has more than that in it, but read the links I provided for more information.

GHG gasses are one of the reasons, so they say, that we have global warming because it traps heat. 

To go Net Zero means that we would reduce our GHG emissions so that it’s reduced to match what is removed from the air. That means that climate change would be reduced back to where it theoretically should be. Again, this is speculative. 

The United Nations had a conference in Paris to reduce GHG being released, but they did not call the initiative Net Zero. It’s called the Paris Agreement by the United Nations Climate Change Conference (COP21) to have countries limit the GHG emissions. 

Don’t forget the backup power!

A carrier’s requirement in the US is to have backup power. I don’t know what the requirements are but most carriers have batteries at macro sites. Depending upon where it is in the US they could have more than others. They also rely heavily on generators to keep the sites on the air.

In areas where tornadoes or hurricanes happen often, you need to have a better contingency plan than in other areas. 

This does impact design and costs. Some carriers rely on a fleet of generators to be delivered immediately after the disaster. In this situation, you have to have emergency personnel pick up, deliver, and connect the generators to each site. This takes a lot of drivers.

Also, you need to have fuel at each site. If power is out for days, then fuel delivery becomes critical. If you know a storm is coming, make sure they top off all the generator fuel tanks.

Fuel could be diesel or propane. Maybe gas, but gas is explosive and dangerous at a site. It’s hard to believe we put it in our cars.

Some generators run on natural gas. These are great because neutral gas usually is the most reliable thing you can have if you can get it connected to the site. Most sites are too remote, but if you are near public gas connections, this is a good way to go.

No matter what your backup plan is, you need to do maintenance and test it regularly. If it doesn’t work in a test, it will fail during an emergency. Then you have a bigger problem! Now you have to fix the problem immediately after a crisis. 

Batteries need to be monitored as well, just because they’re sitting there won’t mean they will work. They need to be looked at and tested if possible. All batteries are capable of failing just like anything else at the site.

Plan properly!

Is Open RAN more energy efficient?

To be honest, I am not sure, even though you can find articles that will argue either side. Some say it is and others say that the goal is to make it more efficient someday.

To be honest, I think we need to see OpenRAN deployed in mass by major carriers and then we can see what they say. For now, let’s just assume it’s on the roadmap.

Liquid Cooling, a brief history:

This is where you use a liquid to cool down equipment. For those of you older like me, think of your fossil fuel car and the radiator. This is one of the earliest examples of liquid cooling. In the early days of automobiles, they had air-cooled engines. Air-cooled means that you rely on flowing air to cool your device. Smaller motorcycles are generally air-cooled. They rely on the moving air to cool the engine. However, they will overheat, causing damage to the motor. Unfortunately, when they do overheat, it’s generally too late, damage is done!

So, the idea of liquid-cooled engines helps the engine stay cooler and prevent damage. If you’ve ever had a car overheat for an extended period of time, then you know that it causes damage to the engine, not to mention expensive repairs. 

Hence, we have idiot lights and temperature gauges to let us know when the engine gets too hot. 

Liquid Cooling in Data Centers

Now, imagine that data centers have the same idea. They connect the equipment to heatsinks and, in some cases, run the fluids through the equipment to a radiator outside in the shade.

The radiator has fans on it forcing the air through to cool the liquid as needed. You have pumps that keep the fluid circulating. Now you have an alternative cooling method for data centers. 

Yes, utility power is a critical thing at data centers. One of the key reasons for the high electric bills is due to the air-conditioning systems. I don’t know if you’ve ever designed or built a data center, but I helped a few times. The cooling system is critical for many reasons. 

Here are a few reasons why:

  • You have to have multiple cooling units, for redundancy. Some people install multiple smaller units. Either way, it has to be redundant. 
  • You need to understand what the power requirements are. Larger units are usually 220VAC in the US and the smaller units are generally 120VAC on 20A breakers.
  • You need to know where the bulk of the equipment will be and route the cool air toward those cabinets. Back then we would normally pump the cool air under the floor and have holes under each cabinet so the cool air would be sucked up into the cabinet where the equipment was.
  • Over the cabinets, we would have the returns so the hot air would immediately get routed back to the cooling units. 
  • All of this planning had to be done in advance and have the option to make changes as plans change. Not an easy thing to plan.

So, you can see it takes a lot of planning and power to make the AC units work. Then, you have to think about the generator. Keep in mind that air-conditioners are inductive loads. That means there is a heavy load on the generator. Add in all the equipment in the data room and you have a large generator to sustain your data center.

If you want to read a good data center article, Vlad-Gabriel Anghel wrote a good article recently found here. Good and long article if you have the time. 

Now, what if we used that technology at tower sites? Remember we already  moved the radios outside, but we have the networking equipment and the BBUs inside the cabinet/shelter.

A short history of Liquid Cooling for Transmitters

I know, most cell sites have their radios outside, but let’s look at transmitter cooling.

Many years ago, broadcast transmitters used tubes to transmit thousands of watts to hit the neighboring towns and people. To keep these tubes and equipment cool they would run liquid through the heatsinks of the equipment. When I say tubes, I mean Vacuum Tubes which use high voltage to power them.

Remember that air conditioning did not work as well back then as it does now. All the same, they put off a lot of power and they needed to be cooled so they wouldn’t burn up and fail. With or without AC liquid cooling was a critical part of the system.

As time went by, most radio station transmitters ran cooler and cooler but TV stations still needed to be water-cooled. 

Think about TV and radio stations. They were very powerful transmitters that used AM for video and FM for audio. Pretty amazing, right? They needed high power back then. They needed to be cooled. Today the broadcast transmitters are all digital and run much cooler. They also just transmit a digital signal, no more analog AM and FM. All that is behind us now, at least in the USA. Broadcast is way more efficient than it was 30 years ago. 

However, TV broadcast transmitters transmit high power, so some still use liquid cooling. They are solid state but require serious cooling that air conditioning just can’t handle. It’s efficient to cool using liquid. When I worked for FLOtv for Qualcomm they used Rohde and Schwarz transmitters that required liquid cooling. They had to be maintained. We still needed air conditioners though, crazy!

If you want to see some, here’s the Rohde and Schwarz product link.

To maintain them you need to be sure the system is good. You have to make sure of the following:

  • No air in the system,
  • Antifreeze had to be a certain mix, usually 35% to 50% antifreeze to water,
  • Bleed out all the air,
  • Verify no leaks, all connections have to be treated,
  • Make sure the pipes are away from traffic and protected,
  • Make sure your radiator is safe and if at a site it needs to have an ice bridge over it, as do all the pipes that connect to it,
  • The pump needs to be tested as do the fans on the radiator.

Maybe you didn’t realize this, but this liquid was not just water, at least not the ones I worked on. They had antifreeze which not only prevented freezing in cold temperatures but would allow the water to heat up over 212 degrees Fahrenheit. Remember you didn’t want it to freeze or overheat. This was all taken care of with the antifreeze you put in the system. 

You also had to check for leaks under pressure which means all your connections had to be treated. That was critical. Sometimes they would start leaking months later, I have no idea why but when that happened you had to repair it in the maintenance window. 

It was always something. 

What about Carrier’s Macro Sites?

OK, here is where I was headed. In today’s carrier sites, the radios are generally located outside the shelter or cabinet. Normally up the tower near the transmitter. Their frequencies are much higher than broadcast and line loss became a problem as carriers went higher on the spectrum chart. 

So that eliminates one cooling problem, doesn’t it?

However, there is networking equipment and a BBU inside the cabinet. The BBU can overheat and needs to be cooled. Fans can do a good job but fans fail. That’s why so much of today’s equipment relies on natural airflow.

So Nokia came out with a liquid-cooled BBU! How cool is that? (I mean that figuratively and literally.)

The idea is that you can cool the BBU by moving liquid through the BBU to keep it cool using a radiator to make it happen. The idea here is that you won’t need AC units, or at least they’re used a lot less. AC units use more energy and need cooling agents. Maintenance requires an HVAC tech to take care of problems. 

With the liquid-cooled model, you could have your tech trained to maintain and repair the units as required.

Acronyms

  • AC = Air Conditioning
  • AI = Artificial Intelligence
  • BBU = Baseband Unit
  • KWH = KiloWatt Hour
  • HVAC = Heating Ventilation Air Conditioning
  • ML = Machine Learning
  • MWH = Megawatt Hours

Links:

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