How Can 5G Massive MIMO Lead to a Sustainable Future?

According to ABI Research, global mobile data traffic will reach 1331 exabyte in 2025 from 23 exabyte in 2019, increasing at a six-year Compound Annual Growth Rate (CAGR) of 97%. The large-scale rollout of 5G is taking place globally but operators are finding out that 5G introduces considerable costs and additional energy requirements. Some operators have even announced that they have taken aggressive measures to reduce 5G energy footprint, e.g., switching off 5G massive MIMO units at night to save power. In a recent 5G trial conducted by Vodafone, a new 5G radio provided by Ericsson was shown to reduce network energy consumption by up to 55%. Ericsson later announced a new massive MIMO (AIR 3268), which claimed to be 10% more energy efficient, thus further lower energy consumption. On September 28, 2021, Huawei launched a new massive MIMO Meta-AAU that delivers a 30% reduction in energy consumption. All vendors are currently progressing their massive MIMO product lines, aiming for better performance, cost efficiency, and lower power consumption.

Massive MIMO has proved to be a cornerstone of 5G radio networks, providing the additional capacity needed as traffic demands increase. Most 5G massive MIMO antennas can be overlaid on existing 4G sites, meaning that operators do not generally have to invest in densifying their networks.

However, with these new 5G rollouts, mobile network energy consumption could witness a three-fold increase by 2025, but at the same time, mobile operators need to build a sustainable and responsible 5G network. Radio vendors have been committed to help mobile operators drive down network energy consumption without compromising performance. For example, Ericsson’s latest radio introduces several improvements:

• It weighs only twelve kg and is 10% more energy efficient than the previous generation.
• The ultra-light weight design not only speeds up 5G deployments but also helps operators to boost capacity, coverage, and top speeds.
• It introduces a deep sleep functionality which is expected to lead to a 70% saving in power during low-traffic times, equivalent to an annual energy saving of 1.2 MWh per site.

ZTE also developed a deep sleep energy-saving technology, and results revealed that energy consumption at the base station can be reduced by 60-80% with deep sleep technology without making an impact on existing network quality. Also, the new massive MIMO Meta-AAU from Huawei employs an ultra-large-scale antenna array technology, accurate algorithm, detailed construction, hardware, and software integration innovation to help realize performance and energy-saving. Test results showed that this new product is able to deliver a 30% increased uplink coverage and downlink coverage. Meanwhile, it improves edge users experience by 25% and reduces energy consumption by 30%.

Carbon-neutral is becoming a mainstream strategy across the world and Research & Development is shifting towards green capability first. Vendors are continuously innovating on green solutions to help mobile operators improve network performance, stabilize the energy consumption, and achieve their net zero carbon emission targets.  

To meet the continued growth in data demands, mobile operators are encouraged to deploy the new radio technology and adopt any innovative solutions to increase their network capacity and improve the quality of service. These new products/solutions enable the highest possible network capacity and performance, and are often capable of reducing the network energy consumption, which in turn leads to lower Operation & Maintenance cost. When energy-saving algorithms are introduced, it is critical to accurately predict the traffic demand and there are several new ideas in the market to achieve this. For example, investing in the development of more advanced machine learning techniques to better predict the data traffic.

In recent years, many new technologies for massive MIMO are being developed. For example, software-controlled metamaterials or programmable metasurfaces have become a concentrated research area. These have potential to vastly reduce energy consumption and costs but are still at the early stage. Critical challenges such as poor propagation efficiency and difficulty in interference management associated with massive MIMO systems still exist for metamaterials. Companies that focus on metamaterials are relatively small, so it may take longer for commercialization due to limited resources. Mobile operators could accelerate the commercialization process by running more trials with vendors and solution providers to gain a better understanding of the practical performance. This will be pivotal to understand the next wave of massive MIMO systems as they expand beyond 64T64R and as the industry starts to address even higher frequencies for 6G, even at THz levels.

The operator sustainability discussion also involves energy creation and how operators power their cell sites. Mobile operators should secure long-term power purchase agreements with their energy suppliers to stabilize energy cost and prefer energy from suppliers that offer renewable supply. Despite the challenges and uncertainties in 2020, more than 80% of the newly added electricity capacity was renewable, with solar and wind accounting for 91%. Solar is becoming more price competitive as the price of photovoltaic has fallen by more than 80%, and battery storage technology is also becoming more advanced. Mobile operators could also generate their own renewables in their cell sites, but the renewable business case compared to grid-power is still challenging. Site-level hybrid energy solutions have long been a popular research area in academia; there are many well-established algorithms that can select the optimal energy sources mix and achieve more energy-efficiency improvements. When investing in renewable energy, there could be a possibility to generate additional revenue. Countries like the UK have generation/export tariffs, where you get paid for generating your own renewable energy and selling any surplus energy.