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The Most Efficient Way to Power 5G DAS

February 16, 2023

5G technology is taking the world by storm and is set to revolutionize the way we communicate and connect with each other, as well as satisfy the need for faster and more reliable internet connectivity. But before 5G can become widespread, infrastructure for it, such as 5G DAS (Distributed Antenna Systems) must be implemented. Unfortunately, this infrastructure is not easy to implement; it can be costly, and has high power demands. That's where DC (direct current) power comes in. In this blog, we will delve into what 5G is, its benefits, what hurdles we must overcome to proliferate it throughout the world, and what role DC power plays in powering not only DAS, but also the 5G future.

Woman holding a phone inside a mall


5G and its Benefits

The Primary Challenge to Proliferating 5G: Power Infrastructure and Cost

Class 4 DC Power: The Solution to Power 5G DAS

5G and its Benefits

5G, the fifth generation of wireless communication technology, is revolutionizing the way we use and share data. With its high-speed transmission, low latency, and reliability, 5G delivers download speeds about 100 times faster than 4G. The key to its success is the use of millimeter-wave (mmWave) technology, which provides the highest bandwidth in the mid-, high-, and very high-frequency bands. This results in better data transfer speeds and opens up new possibilities for connected vehicles, smart cities, and the Internet of Things (IoT). The demand for fast and reliable internet is increasing, in fact Gartner predicts that by 2028 there will be over four billion connected IoT devices in commercial buildings, including data centers, with 5G at the forefront of connectivity. Additionally, some analysts predict that data rates will reach almost 107 exabytes (EB) per month by the end of 2023 (39% CAGR). This increase in demand acts as a major tailwind that emphasizes our society’s need for 5G (and the infrastructure that enables it). A critical component of the transition to 5G networks is the implementation of Distributed Antenna Systems (DAS) and the way we power them.

5G Infrastructure and DAS

A DAS, or Distributed Antenna System, is a type of wireless infrastructure technology used to enhance the coverage and capacity of cellular networks, including 5G networks. In the context of 5G, DAS refers to a network of antennas and associated components that are dispersed throughout a building, campus, or other large coverage area. They are most beneficial in indoor spaces because there are usually more barricades that block network signals in buildings (such as walls). Cell towers provide adequate 5G coverage outdoors, but more than 80% of voice and data usage occurs indoors, so facility managers need a wireless solution that distributes reliable cellular coverage for the entire facility and for connecting multiple buildings on a campus. That’s where indoor DAS comes in. DAS essentially ensures that building occupants have access to fast and reliable 5G internet, even in areas where traditional cellular signals may be limited or weak (such as underground subway terminals).

subway terminal underground with train speeding by

DAS can be described as a distributed network of small "base stations", acting as a single large cell. Base stations in DAS are also known as small cells, but small cells can also function individually, or as an individual network. Small cells are reminiscent of Wi-Fi routers, but work in a similar way to network towers that emit wireless signals; both have built-in antennas. Small cells cover a small area and are used to extend coverage to areas or to add network capacity in locations with very dense cell phone usage. There are a few different types of small cells, including microcells, picocells, and femtocells. Click here for an article that differentiates between these three types of small cells.

table comparing the different types of small cells including microcells, picocells, and femtocells
Difference between different types of small cells

Essentially, our cellular networks must evolve in order to support the massive amounts of data that we’re already using, and be able to support the additional data generated by people adopting IoT into their everyday lives. However, there are some hurdles that 5G must overcome before it becomes widespread. One of the largest hurdles is how Small Cells and DAS infrastructure will be powered. The solution must be reliable, highly efficient, and able to provide high enough levels of power to support the additional bandwidth of 5G networks, and additional power needs of the higher quantity of antennas associated with DAS.

Rendered apartment building with DAS in each room
Image Source

The Primary Challenge to Proliferating 5G: Power Infrastructure and Cost 

The main hurdles facing 5G proliferation can typically be broken down into just three categories: regulatory approval, fitting 5G into our current world, and powering 5G infrastructure efficiently and cost effectively. In this article, we’ll be focusing on the third category, as it’s perhaps the most significant. 

Regulatory Approval

5G requires regulatory approval from governments, almost everywhere around the world, which may take time and may be subject to change.

Fitting 5G into our Current World

5G needs to be able to coexist with our current technologies, as the transition to 5G will not happen overnight. The challenges related to this are: 

  1. Interoperability/Compatibility with Existing Networks and Devices:

The shift to 5G will not happen abruptly, meaning that both 4G and 5G will need to be utilized simultaneously for a period of time, which creates a challenge because not all networks and devices currently support 5G. For example, iPhones before the iPhone 12 do not have support for 5G connectivity.

  1. Competition with existing technologies:

5G will face competition from existing technologies, such as Wi-Fi 6, which provide similar services and may be cheaper and more widely available.

Powering 5G Infrastructure Efficiently and Cost Effectively

Perhaps the most significant hurdles for 5G are the infrastructure, technology, and costs associated with powering it (which all go hand-in-hand). Let us explain. As we mentioned earlier, DAS, or Distributed Antenna Systems, are essential when it comes to the proliferation of 5G. This is because 5G typically operates at a higher frequency than 4G

frequency spectrum determines 5G coverage and speed diagram depicting different frequency levels of 5G from low to high
Image Source

The shorter wavelengths allow 5G networks to carry vast amounts of data with minimal latency (minimal delay). However, along with shorter wavelengths, come a couple challenges: 

  1. The shorter the wavelengths, the shorter the range, so 5G wireless communications towers need to be higher in order to cover similar ranges to those of 4G towers.
  2. It’s more difficult for shorter wavelengths to penetrate barriers like concrete walls.

DAS helps to overcome these two disadvantages, especially in indoor locations, where dramatically high towers (200 - 300 ft. tall) are impractical. The antennas in DAS (also called base stations) can be quite small, so having many of them throughout a building is relatively practical, and provides a strong 5G network throughout a space. They can even exist inconspicuously, such as on light poles, traffic lights, walls, ceilings and more. Implementing more of these is called small cell densification, and will require a big investment. However, it’s a necessary part of proliferating 5G networks. As we mentioned above, there are a few different types of small cells, and so the type of small cell implemented would depend on the intended application.

Why 5G Needs More Power: DAS vs. Macro Towers 

In order for 5G technology to be widely available, Distributed Antenna Systems (DAS) are crucial. But how will the infrastructure that powers DAS be sustained? About 80% of each 4G network utilizes macro towers, with small cells making up the remaining 20%. On the other hand, 5G networks heavily rely on small cells (indoors and outdoors), as they make up about 80% of its infrastructure. This, along with the fact that macro towers in 5G infrastructure are significantly larger than those in 4G infrastructure (as per mentioned), results in increased power consumption. The increased power demand in 5G infrastructure leads to power consumption being almost 2x higher in 5G networks than in 4G networks. So, in summary, powering the DAS and macro towers is the primary reason for the higher power consumption in 5G networks.

Source: Airspan Networks. Click here for a larger version of this image.

Diagram depicting the height difference between a 4G tower and 5G transmitter mast (tower)
5G macrocells are mounted on top of 5G transmitter masts, which must be taller than their 4G counterpart because of the shorter wavelengths they emit. The alternative to this it to have a high quantity of 5G small cells as part of a DAS.

This could have a negative impact on the environment if power is not delivered efficiently. Additionally, because the macro towers are so tall, cables powering them not only need to deliver higher voltages (to reduce line losses), but they must also be lighter (weight wise). In sum, a big challenge facing the proliferation of 5G is efficiently providing adequate power to 5G infrastructure, and doing so with lighter cables (cables with smaller gauges).

Powering 5G DAS with Class 4 Power 

Luckily, there is a solution that is powerful, efficient, and makes use of low-voltage wiring practices (and lighter gauges of cable).

In the past, alternating current (AC) power was typically used in higher voltage applications for telecom. If DC power was required, low-voltage (48V DC) would be used along with heavy gauges of cable to deliver adequate power at long distances. Heavy gauges of cable were used with low-voltage DC because, according to the formula for power, lower voltages result in higher currents, for higher power levels. When there are higher currents, additional space is required within a cable for the current to move through cables without as much resistance. To better understand this, have a peak at the image below for a good analogy. Without that voltage pushing the current through, the current is only really able to make it through easily if the cable gauge were to be wider (with more space for it to pass through).

AC power was used in higher voltage applications because infrastructure for AC power usually is cheaper when it comes to delivering power over long distances (except at the break even distance). But, recently, there was a development in electrical regulation for the use of direct current (DC) power, so DC can now often be used in lieu of AC power. Essentially, the 2023 National Electrical Code (NEC) now includes the addition of a new class rating for DC power systems that are fault-managed and can provide up to 450V DC. This class rating is called “Class 4 power (CL4)”, and can be found under Article 726 of the 2023 version of the NEC. UL has also released a new standard for Class 4 power systems and cables under UL 1400-1 and UL 1400-2.

Diagram showing how a class 4 power system works with a transmitter and receiver
How Class 4 Power Systems Work

The addition of Class 4 was the first time in over 45 years that a new class rating was added to the NEC (Class 3 was added in the 1970s). Out of the 3 class ratings (class 1, 2, and 3), Class 2 systems, such as Power over Ethernet, are popular because they provide suitable protection against both fire and shock hazards. Class 2 systems also only require low-voltage wiring practices, so they use less insulation, and don't require mechanical protection or conduit.

Similarly to Class 2 systems, Class 4 systems make use of low-voltage wiring practices and are considered safe from both a fire and shock standpoint. However, Class 4 systems are fault-managed instead of power limited. This means that electrical lines are constantly monitored for faults by an integrated safety computer, and power is shut off immediately if a fault is detected. Lines are constantly monitored between the power transmitter, and receiver (pictured above). The intelligent DC to DC converter then steps down power appropriately for the load. This fault detection makes it safe for up to 450V DC to be sent, line to ground, using low-voltage wiring practices. Additionally, because relatively high voltages can be sent, the system incurs less line losses, and cable gauges can be lighter. The reason it incurs less line losses comes down to simple physics; because more voltage (and therefore less current according to the formula for power) can be sent, less heat is also emitted from lines. Less heat emitted is equivalent to less energy lost along lines.

formula for power and resistive power losses

DC Power’s Role in Powering 5G Infrastructure

But why would using DC instead of AC power provide a better solution for powering 5G infrastructure? It comes down to a few reasons. 

1. DC is Efficient: 5G antennas are DC devices, so they consume DC power

DC devices consume DC power, but power grids generally distribute AC power. Manufacturers take this into account in the design process of their DC powered devices by including AC to DC converters in device drivers. Unfortunately, these converters can be an afterthought, and are often not very efficient, wasting DC powered devices about 20% of power consumed. When DC powered devices get the DC power they require, right off the bat, the need to convert AC to DC power is eliminated, along with energy wasted by these conversions. This is a big reason why DC power distribution is so beneficial in telecom applications; it ensures 5G antennas get the DC power they need, so they waste about 20% less energy than if AC power were distributed to them.

It’s essential that the power distribution system utilized for telecom is efficient because of the large amount of power telecom consumes. In telecom, if 20% of energy consumed is wasted, this has even bigger implications for the environment than in lower demand applications. Additionally, components in 5G infrastructure need to be able to provide a high enough level of efficiency to effectively dissipate heat. This is important because every 10°C rise in component temperature halves the MTBF (Mean Time Between Failures), So designers must concentrate on optimizing thermal management, and therefore efficiency of components.

DC power is also more compatible with loads in instances where tapping AC directly from the pole is not feasible. In these cases, a centralized plant is utilized to provide DC through the use of DC/DC converters.

2. DC is Efficient: There are less line losses along cables in DC distribution and transmission

Eliminating AC to DC conversions isn’t the only way DC power distribution powers 5G infrastructure more efficiently, it’s also possible to optimize the efficiency of power distribution by reducing losses along cables. If you’re familiar with power transmission methods, you’ll know that it’s usually less expensive to distribute high-voltage AC (HVAC) power (until the break even distance of about 600 km). This is because HVAC is compatible with transformers, while high-voltage DC (HVDC) is not. Despite HVAC’s commercial benefit, DC power actually travels more efficiently down lengths of cables, when compared at the same voltage. This is because DC suffers from far less line losses than AC power. For example, DC power has no reactive power losses, and doesn’t suffer from the skin effect. In taking these, and other factors into consideration, EE Power determined that the increased efficiency of HVDC over HVAC reduces losses from 5 - 10% in an AC transmission system, to around 2 - 3% for the same application in HVDC. Thus, by distributing DC power along cables that power 5G antennas, 2 - 3% of energy that would’ve otherwise been wasted, is conserved. 

3. Lighter Cables: Higher DC voltages allows for lighter cables

Telecom applications typically makes use of low-voltage DC (48V DC) systems when DC is required, but there are many benefits to Class 4 being utilized in 5G infrastructure since it was introduced. Class 4 rated power systems are capable of safely handling up to 450V DC due to their built-in fault management features. Because these systems can deliver higher voltages, cables used in these systems can be lighter because they don't have to support as much current (according to the formula for power, see below). Additionally, minimal mechanical protection and conduit can be used safely in a Class 4 power system because of its fault-management. Lighter cables are ideal in telecom applications because of how high 5G transmitter masts need to be in order to emit 5G signals at a long range.

formula for power and resistive power losses

4. Reliability: Store DC power in a backup battery system

Batteries only store DC power, so it’s easier to implement a backup battery system, and thus minimize downtime, with DC power. Backup battery systems are especially important in 5G infrastructure because some 5G infrastructure is at a higher risk of failure than 4G infrastructure. This is because 5G's high-frequency wave lengths can't travel well through obstacles, as we mentioned before. This is not only an issue in indoor settings, but also sometimes in outdoor settings. To compensate for signals being blocked by outdoor obstructions, such as buildings or mountains, carriers are installing many small cell sites near each other, along with many repeaters. However, because these small cells (part of a DAS) are so small, they are at a higher risk of failure from storms and accidents. 4G infrastructure is bigger than those small cell antennas that are part of a DAS, so it’s more resistant to harsh weather conditions. Because small cells in 5G infrastructure are at a higher risk of failure, a reliable backup battery system is even more important in 5G infrastructure.

Alternative DC Power Distribution System: Power over Ethernet (PoE)

Other DC power distribution systems existed before Class 4 rated systems, such as Class 2 power systems. Power over Ethernet (PoE) is an example of a Class 2 DC power distribution system. Perhaps you’ve heard of PoE, as it’s been gaining popularity for a couple decades. Unfortunately, PoE is probably not the solution when it comes to powering 5G infrastructure. Although PoE is a DC power distribution system, and so has many advantages, it is not capable of providing the significant power needed for 5G DAS or macro towers. In fact, the most recent version of PoE can only provide up to 100 W. 

Class 4 DC Power: The Solution to Power 5G DAS

As you can see, because of the demanding power requirements for 5G, high-reliability Class 4 DC power systems could be the electrical solution that enables 5G to become widespread. If you’re looking for a Class 4 power system that can be used for 5G infrastructure, check out Cence Power.

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Erin Law

Erin is the Creative Director at Cence Power. She has a New Media degree from the University of Toronto and 5 years of experience in the communications field. She has also done digital content creation for dozens of clients through her own business called Story Unlocked. Erin loves technology, especially when it makes the world a better place.

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We improve the value of commercial and multifamily buildings with an intelligent DC power distribution system that's pain-free to install. It combines the benefits of low-voltage wiring practices with voltage capabilities of up to 450 Volts DC.

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