Sustainable networks

Mobile subscriptions have grown from 6 billion in 2011 to 8.1 billion in 2021, with smartphone subscriptions growing from 0.7 billion to 6.3 billion over the same period, driving traffic from just below 0.25EB per month to 65EB per month – a factor of almost 300 times. This traffic growth has been supported by an increased population coverage and multiple mobile generations running in parallel, adding the required traffic capacity.

Whilst traffic has grown exponentially over the last 10 years, service providers’ global network energy consumption has risen by just 64 percent, from 91TWh to an estimated 150TWh. This illustrates that there is only a weak correlation between traffic growth and increased energy consumption. There is a stronger linkage to the deployment of new bands and equipment, reflected in increasing population coverage with multiple mobile generations.

Technological innovation rising to the challenge

Major technological innovations have enabled mobile networks to support significantly more traffic while consuming only marginally more energy. Through 5G standards and specification, new innovations are being deployed to not only continue supporting growing data demands, but to help drive down energy consumption. The Radio Access Network (RAN) is a key focus area, as it accounts for the vast majority of the total energy consumption in mobile networks.

One innovation area supporting traffic growth is the evolution of spectrum efficiency.1 This has significantly increased with every generation of mobile technology, including rising by 200 percent for 5G compared to 4G. This stems from modulation improvements and scale effects as bandwidths increase and are major contributors to preventing energy consumption from growing at the same rate as traffic.

When examining typical network traffic patterns, several short gaps in data transmissions can be observed, even during highly loaded times. During these gaps, power consumption is reduced by quickly putting components into sleep mode, and only activating them again before the next transmission. Longer gaps mean more components can be put to sleep, further lowering energy consumption.

In the 4G standard, the gaps where Micro Sleep and other energy-saving features can operate are very short – 0.2ms at the most. The 5G New Radio (NR) standard has been designed based on knowledge of typical traffic activity in radio networks and the need to support sleep states in radio-network equipment. This allows 5G NR to provide much better support for implementing energy-saving features.

The time between mandatory transmissions can be as long as 20ms in standalone mode and 160ms in non-standalone mode – 100 to 800 times longer than 4G. In addition, 5G NR requires far fewer always-on signaling transmissions in the frequency domain.

Superior radio network energy performance was an important consideration when the 5G NR standard was agreed upon. Its ultra-lean design creates new possibilities for drastically decreasing network energy consumption compared to previous generations. It also has a much higher capacity and is able to produce lower loads as a percentage of the total capacity a certain traffic volume utilizes. This, coupled with the ability for deeper and longer periods of sleep, results in the potential to significantly reduce the energy consumption of 5G NR products – eventually lowering overall network energy consumption.

A holistic approach for service providers

The deployment of every new mobile generation since 3G has led to concerns about increasing mobile network energy consumption, and 5G is no exception. There are fears that if 5G is deployed in the same way as previous generations to meet rising traffic demands, the energy consumption of mobile networks will increase dramatically. However, while historic figures show a rise in global energy consumption over time, it is not as significant as some early expectations. Utilizing efficiency gains from new mobile generations, combined with new innovative operational approaches, has been critical for keeping network energy consumption at a manageable level.

To meet the industry aspiration for net-zero carbon emissions, an approach that breaks the upward trajectory of global network energy consumption is required. Leading service providers are addressing this challenge by applying a holistic network approach that will gradually reduce energy consumption. This is achieved by combining network modernization with new features and capabilities that can be applied in network design, build and energy-smart operations, as exemplified in Figure 35. In addition to this holistic approach, the switch to renewable energy sources is critical for achieving the overall reduction in carbon emissions.

Building 5G with precision

Having a wide range of equipment to cover different deployment scenarios enables networks to be built with precision. In order to fit in more locations, an ultra-lightweight design is used in the latest Massive MIMO radios making them smaller and more energy efficient. This was illustrated at the site level by Vodafone UK, which placed an antenna on the roof of the Speechmark – Vodafone UK’s London office. The deployment of the latest antenna-integrated radio solution saw equipment’s daily energy consumption drop by an average of 43 percent compared to previous generations, and by as much as 55 percent at off-peak times – all while still meeting the site’s traffic demands.

A 360-degree view of an energy-efficient mobile service

A challenge for Indosat Ooredoo in Indonesia was to reduce power consumption without degrading KPIs in a highly loaded 4G residential cluster of 68 macro sites. To achieve this, they took a holistic approach, activating energy-saving software and operating the site infrastructure intelligently. The 4G energy-saving features focused on sleep modes, additionally embracing AI and data analytics for intelligent management of infrastructure across 3,000 sites. Indosat Ooredoo realized improved operational efficiencies and achieved significant power savings whilst maintaining network KPIs.

Introducing renewable energy to mobile network sites

The switch to renewables goes beyond purchasing sustainable energy. In a decisive step towards net-zero emissions, Deutsche Telekom has brought solar power to commercial mobile broadband sites for the first time.

The 12sq m solar panels were installed at Deutsche Telekom’s mobile site in Dittenheim, Germany during the second half of 2020. Throughout July 2021, they contributed an average of 14 percent to the site’s overall power supply, increasing to about 83 percent between 12:00 PM and 2:00 PM. This enabled average solar energy harvesting of 11.5kWh per day in June, increasing to 15.1kWh on sunny days. Across the year, including winter, solar is forecast to contribute to about 11 percent of total RAN site energy.

Mobile networks are only part of the story

A combination of switching to renewables, modernizing equipment and fully utilizing the energy-saving capabilities of today’s mobile networks can immediately make a positive difference, contributing significantly towards service providers’ net-zero emissions targets.

However, the societal impact is much greater. Connectivity is an enabling technology, representing a fast, scalable tool to help address climate change. Indeed, digital technology may be the most powerful, scalable tool the world has to tackle the climate crisis. As an accelerator, it could reduce global emissions by up to 15 percent by 2030,2 and indirectly support a further reduction of 35 percent through influencing consumer and business decisions and systems transformation.

¹ “Spectrum efficiency” here refers to bits per second, per hertz, per cell (essentially, the information rate per cell over a given bandwidth).

² Exponential Roadmap (January 2020), exponentialroadmap.org.