Upgrading to more efficient cellular radio towers could save enough electricity to power cities such as Phoenix, New Orleans or Seattle, according to a new study produced by US research firm J. Gold Associates.

Annually, US cell sites use a total of almost 21 million megawatt hours (MWh) of power. That's the equivalent of the average power used by almost two million households.

"Cellular services have become a critical infrastructure component of modern life. It's hard to imagine not being able to communicate on the go with our mobile devices, or increasingly through a wireless home gateway enabling Internet services to both residential and business customers," the report said. "But not often discussed is the burden that the numerous cell sites places on the electricity supplies required to keep them powered and the costs associated with the power supplied."

Each 10% reduction in total cell site power results in enough electricity saved to power the equivalent of 195,000 households. And a 40% reduction provides enough electricity to power the equivalent of almost 782,000 households, according to the study, "US Cell Sites- a Sustainability Analysis."

By upgrading both the radio hardware and the management software, each cell site could save as much as 40% of its electricity needs, the report states.

"Sustainable reuse of the electricity can be used to power a large number of equivalent households without the need for new power sources," the report said. "The amount and cost of electricity to operate our modern cellular infrastructure is massive and has an effect on users' subscription costs as well as load on the power grid and creation of greenhouse gases from power generation.

"It would be beneficial for the industry to move in this direction as quickly as possible," the study concludes.

A typical modern, high-performance cell site would probably cost about$200,000, according to Jack Gold, principal analyst and author of the report. Each carrier would be responsible for their own equipment, even if they are sharing a physical tower with others. Typically the tower is owned by a tower company, which then leases the site to the various operators (similar to a multi-unit rental such as a condominium or apartment building).

"So each carrier is responsible for their own upgrade of their equipment," Gold said in an interview.

Telco workers install a 5G antenna on a cellular tower.

According to the Cellular Telecommunications Internet Association (CTIA) there were 417,215 cellular sites in the US at the end of 2020. While that number is a moving target as more cell sites are added as new areas and/or services are deployed, J. Gold Associates used that number for its report's calculations. (The CTIA is a trade association representing the US wireless communications industry.)

The radio element of a cellular telecommunications network is called a RAN (which is short for radio access network). The typical RAN lasts about eight years before it requires upgrades or replacement, Gold said.

(Because there is a large variation of age of cell sites globally, it's difficult to estimate how many currently need to be replaced, according to a spokesperson for Swedish networking and telecommunications company Ericsson.)

Instead of simply replacing old hardware, moving to a more virtualized environment rather than dedicated hardware will help lower the overall need for power, Gold said.

AI offers opportunities

Additionally, by using artificial intelligence(AI) in cell site management software, service providers can operate the infrastructure more proactively with tools to control passive equipment and enable predictive maintenance and no-touch problem-solving to reduce costs, site energy usage and site visits.

"AI tools are useful in managing the cell sites' hardware, by understanding better just how much power is needed for each connection, rather than just turning radios on and off at full power which is basically what happens on the older equipment," Gold said. "If you're close to the tower, you don't need to transmit to me a signal at full power."

AI can also recognize previous patterns and manage equipment on that basis ( the software could "learn" that a site rarely has traffic from 2 a.m. to 3 a.m. and puts it on minimal power). That kind of granular management can reduce power significantly. And better antennas, such as more efficient 5G Massive Multiple Input Multiple Output (MIMO) devices, also can help with limiting the needed broadcast power.

A 5G antenna atop a roof.

Ericsson recently announced a more energy-efficient RAN that's powered by the company's latest generation silicon, which it claims uses 25% less power. The portfolio update includes everything from dual-band radios to ultra-lightweight Massive MIMO radios, low-footprint antennas, and energy-saving software features.

"Also, newer devices can have software installed that can interact better with the management to take into account a series of power-savings features, much like newer PCs also do that better than older PCs," Gold said.

Another crucial component for energy efficiency is the power amplifier (PA) in the radio used to generate the signals to be transmitted, according to Ericsson. Typically, the PA consumes more than 60% of the radio's power. As a result, the efficiency of the radio hardware can be optimized for the specific output power or configuration used by continuously integrating more discrete steps into a single package, adopting new technology such as high-efficiency Gallium nitride (GaN) and wideband PA technology multi-band radios, Ericsson's spokesperson said.

The move to 5G also plays a role

About a quarter of the world's population currently has access to 5G coverage. Some 70 million 5G subscriptions were added during the first quarter of 2022 alone, according to Ericsson. By 2027, about three-quarters of the world's population will be able to access 5G, according to Ericsson's June 2020 Mobility Report.

Since creating 5G RANs in 2015, Ericsson said it has shipped 8 million devices to its customers - "the most installed 5G-ready radios in the industry," a spokesman said via email.

Today, there are about 210 5G networks in commercial service, and Ericsson claims to lead the market with about 50% (120 networks) of the world's mobile 5G traffic outside of China.

In an earlier report, Ericsson claimed there's a perception that older equipment on cellular sites can handle the increased traffic demand from more mobile devices and upgrades to 5G, which the company disputes.

"The transition from 4G to 5G brings a huge increase in compute requirements - they have increased by a factor of more than 150," Ericsson's spokesman said. "While general compute solutions can be used for 5G, to truly deliver 5G performance with the highest energy efficiency, you need purpose-built silicon. Ericsson's System on a Chip (SoC) design is the optimal solution to achieve this."

Ericsson claims its newest 5G Radio System can lower energy consumption by about 30% when used to modernize current infrastructure. The system supports standalone and non-standalone 5G, 4G, 3G and 2G access technologies. "It delivers high levels of orchestration and automation for operational efficiency, and provides up to 20% savings in infrastructure with cloud?native operations," the company said.

"In some cases, it even pays for the upgrade within three years," the company said in its report. "Customer cases show that service providers have reduced site energy consumption by up to 15% through intelligent site control solutions."

However, some studies claim 5G consumes as much as twice the power as 4G systems. "A typical 5G base station consumes up to twice or more the power of a 4G base station, Matt Walker, chief analyst with MTN Consulting wrote in a report titled "Operators facing power cost crunch."