Forging more sustainable mobile networks

Sustainability is an integral part of the design and purpose of future mobile networks. Nokia believes digitalization and connectivity solutions are critical to support the resolution of many of the global problems facing society today – environmental, social and economic.

The United Nations has urged countries to commit to targets that help them achieve net zero by latest 2050. To keep global warming restricted to no more than 1.5°C - as laid down in the Paris Agreement - emissions need to be cut by 45 percent within 2030.

However, climate is not a standalone part of nature, and we are dependent on the natural resource base layer which includes the three following interconnected sectors: biodiversity, geodiversity and air, including climate and air quality. All three categories are needed for a stable environment to live and operate businesses. A healthy natural resource base ensures companies, countries, nature and life are able to develop and grow sustainably.

Stepping up to net zero

The journey towards net zero will happen in a progressive manner for mobile networks. The steps described below will not only help reduce total energy consumption but also allow the network to provide enhanced user experience.

Network modernization will be an important element in moving towards net zero, and it would encompass a continuously evolving radio access network (RAN), upgraded software and innovative site solutions.

Recent advancements in automation, artificial intelligence and machine learning (AI/ML) will play a crucial role, too, as the industry moves from 5G to 5G-Advanced and to 6G. Communications Service Providers (CSPs) will be able to leverage the capabilities offered by the 5G specifications to enlarge the network sleep opportunities and improve energy-efficiency compared to LTE. 5G-Advanced is introducing further capabilities to augment energy saving – up to around 15 to 30 percent - under low to medium load levels without compromising end user performance.

6G will take energy efficiency a step further since minimal energy usage and energy efficiency will be central to its design, implementation and operation.

Developing a more sustainable network

A major step in the development of networks would be to leverage advanced hardware components and the adoption of novel radio unit architectures in the RAN. The energy consumption of the network for any given deployment depends on the load in the system which is non-linear. The load varies substantially throughout the 24-hour period, with peak loading only occurring for a few instances during the day. Since network dimensioning is made to handle the busy hours, it is estimated that, on average, up to 70 percent of radio resources are in idle, and 80 percent of sites only carry about 20 percent of traffic, permitting plenty of opportunities to reduce energy consumption.

“5G introduced native beamforming for control and user plane channels which enabled high spectral efficiency with mMIMO deployments. The maturity of the technology employed for mMIMO has evolved since the early deployments allowing for improved performances and substantial reductions in energy consumption. However, mMIMO radio units continue to strive for higher performance via e.g. a higher number of transceiver chains,” says Jinfeng Du, Department Head, Radio Systems Research at Nokia Bell Labs. “A closer look at the power consumption distribution in 5G massive MIMO deployments help to identify key components that dominate the overall power consumption, which will be the areas that have the highest potential for energy saving. Therefore, research and design should focus on these areas to make 6G better in energy efficiency,” he adds.

The next major requirement is algorithms that can make use of the modular design by efficiently operating an appropriate number of modules depending on the traffic patterns and load levels.

In our vision of 6G, we aim to create a design that builds on the foundations of 5G-Advanced but goes beyond the existing capabilities of energy efficiency and energy saving. “Standardization will play a crucial role. Unlike previous networks that are ‘always-on’, 6G networks will be designed to be ‘always-available’. It means that the network will only be awakened when necessary, such as when a device requests network operation. Achieving this will involve optimizing the always-on signal design, resulting in a leaner carrier compared to 5G. This will enable significant energy saving at the base station and ensure seamless connectivity without having to compromise energy consumption”, says Daniela Laselva, Distinguished Member of Technical Staff at Nokia.

To further improve energy efficiency, it will also be paramount to design optimized energy saving adaptation techniques that can deactivate unnecessary resources, especially antennas and transmit power, when the peak capacity is not required.

Boosting software

Nokia’s latest generation Single RAN software can support 2G-5G radio technologies concurrently. The most energy-efficient technology, today, is 5G Standalone with Carrier Aggregation, with which Nokia is able to maximize both the energy efficiency and performance compared to previous generations.

Energy efficiency can be further improved with a wide range of energy saving RAN software features which are designed to mute resources when not required. For example, it is possible to deactivate power amplifiers when there is no data to transmit during active operations. And during times when there is very low traffic or even no traffic, MIMO and Massive MIMO transmitters can be muted partially to keep the network available, or even the whole radio unit can be switched off going into deep sleep, when there is no mobile traffic on capacity layers.

Typically, operators design their networks using the same maximum transmit power setting for all cells of a network layer, spectrum band or carrier. This aims to reduce the effort needed in the network design phase and simplify network parameter consistency checks. However, this approach does not consider individual cell conditions with respect to interference and load, which means that some cells will be allocated much more transmission power than would be needed. Nokia’s Digital Design approach considers each individual cell in the network with respect to interference, load, and beam-set configuration. The result is a cell-based optimized configuration with overall lower transmit power that has a positive impact on both the environmental footprint and the energy bill, without compromising network performance and end user experience.

Marching towards net zero

Energy efficiency will be an important metric for the next generation of networks and in the case of 6G, it must be among the first design fundamentals. This guiding principle combined with innovations in network operation, architecture, and technology components could work in sync to dramatically improve the energy efficiency of 6G. While we will have to wait until around 2030 for the first 6G networks to be commercially available, it is vital that the telecom industry starts planning now. “For 6G to achieve the desired level of energy efficiency, a deeper collaboration within our industry and others is essential to better understand their needs and facilitate wider adoption,” says Navin Hathiramani, Senior Standardization Specialist at Nokia.

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