Feature Mobile network operators (MNOs) continue to expand the coverage and capacity of their fourth and fifth generation (4G/5G) infrastructure globally as they seek to attract new customers and grow revenue from the provision of innovative services to consumers and enterprises.

But the large amounts of electricity needed to power the base stations, antennae and cell towers broadcasting wireless signals which make up those networks are still a major pain point. Energy efficiency has subsequently become a core strategic focus for MNOs striving to meet environmental targets and boost profits.

The telecom industry accounts for about 1 percent of the global electricity consumption, which is equivalent to approximately 300 terawatt-hours annually, according to ZTE's Every Bit Going Extremely Green 2024 whitepaper. Another study published by the GSM Association (GSMA) reported that energy and electricity expenses make up about 20 to 40 percent of total operating expenses and 80 to 90 percent of network expenditures. The Radio Access Network (RAN) itself represents more than 80 percent of this - a challenge which mefficient radio infrastructures have all been applied to address.

More efficient equipment and processes have been identified as a major potential enabler of cost savings for MNOs even while they accelerate their move toward net-zero carbon emissions. This is an ongoing ambition for many telcos around the world - the Carbon Disclosure Project and GSMA Intelligence also reported that approximately 85 percent of global operators have committed to the Science Based Targets Initiative (SBTi) to achieve net-zero emissions. Most of them aim to achieve that by 2050.

Supporting MNO sustainability ambitions

ZTE aims to support those MNO sustainability ambitions by enhancing the energy efficiency of its 4G/5G RAN network infrastructure and solutions. Citing GSMA statistics, the company pointed out that remote radio units (RRUs) tend to consume more than 50 percent of a service provider's network energy consumption for example, while 80 percent of an RRU's power consumption is due to the power amplifier (PA). Apart from reducing power consumption, deploying highly efficient RRUs is crucial for introducing new spectrum and 5G New Radio, it said.

To that end, the Mobile World Congress event in Barcelona earlier this year saw ZTE present its Super-N 2.0 near-constant Power-Added Efficiency (PAE) radio platform. PAE is the ratio of the difference of the output and input signal power to the DC power consumed by a PA. ZTE claimed that the radio platform's near-constant PA efficiency enables up to 30 percentage points of efficiency improvement, while simultaneously delivering 35 percent lower RRU power consumption than the industry average.

Super-N 2.0-based RRUs can decrease power consumption across all levels of usage, said ZTE, particularly in periods of low service demand. The company estimates that power efficiency is three times that of traditional PAs at 10 percent service load and 1.5 times at 30 percent service load. At loads beyond 30 percent, it remains almost constant.

These gains are enabled by various features. The Super-N 2.0's platform features smaller and more densely packed PA transistor array for example, as well as an "on-demand" adaptive activation method for PA die-casts, and patented quasi-neural network algorithm for adaptive and precise matching online to the architecture, explained ZTE.

5G-AI integration enables precise power saving

A GSMA panel at the same Mobile World Congress 2024 event saw Tang Xue, Vice President of ZTE, discuss what she believes will be an inevitable integration of 5G and artificial intelligence (AI). This will pave the way for AI processing at the edge node closest to users, which will help to effectively reduce data transmission delay, improve data processing efficiency, and reduce the cost of AI applications, believes Ms Tang.

Integrating AI natively into base stations - independent of network-level AI platforms - will enable real-time decision making that balances user experience and energy consumption based on services awareness, explains ZTE. This will allow network resources to be distributed optimally based on real-time needs and service patterns, so different levels of network equipment shutdown can be matched in real time with traffic load demand without impacting user experience.

ZTE's 5G-Advanced (5G-A) baseband unit (BBU), for instance, integrates communication and computation for rich AI applications. It implements more precise power-saving strategies and facilitates autonomous network operations and maintenance (O&M).

"5G and AI integration as well as 5G-A's new capabilities and scenarios need a lot of computing power," Ms. Tang said. To help MNOs accommodate that compute power, ZTE's 5G-A BBU implements computing power orchestration which can adapt to full scenario requirements, including site computing power enhancement, inter-site computing power sharing and computing power integrated in a Computing Force Network (CFN) infrastructure.

Apart from 5G-A BBU and the integration of 5G and AI at edge nodes, Ms Tang said that ZTE's RAN Composer AI-based RAN intelligence solution also enables precise resource allocation based on network serving capability and service requirements to increase energy efficiency and improve the user experience.

Put simply, ZTE is leveraging Al, big data analysis and automation to maximize traffic performance with minimal energy use by adopting a "one cell, one policy" approach. The aim is to let MNOs achieve an optimal balance between energy consumption and performance which they can apply to various common network coverage scenarios, including university campuses and business parks, for example.

Hibernation cuts big source of energy use

Radio devices can consume a lot of power even when network traffic is extremely low. That's because the components embedded in active antenna units (AAUs) and RRUs continue to use electricity even when in deep sleep mode.

ZTE designed its hibernation technology to reduce AAU power consumption down to as low as 5 watts when there's no traffic on the network. When the same technology is applied to RRUs, power consumption can be cut further to as low as 3 watts. While in hibernation mode, all modules of the AAU/RRU, except for a tiny power supply module, are muted says ZTE.

The company has already implemented this hibernation technology into more than 350,000 5G AAUs in China

For small cells, hibernation enables 0 watt at 0 bit in pico RRUs when there is no traffic. The cell can be awakened in seconds on any attempt to access service. A ZTE trial conducted with China Mobile's Jiangsu Branch late last year demonstrated the application of the RRU hibernation technology, which supports the development of zero-carbon base stations.

Scaling power saving solutions to all sites further reduces energy use and emissions from mobile networks, says ZTE. The company has also introduced a radio frequency (RF) pooling solution that dynamically shares idle output power of one sector with other sectors to ensure an optimal user experience while improving energy efficiency of bit/watt by up to 20 percent.

Energy efficiency indicators continue to evolve

Research into wireless network energy efficiency conducted by international standards organizations such as the ETSI, ITU, and 3GPP has proposed energy efficiency indicator definitions that correspond to different scenarios and service types. The GSMA defines wireless network energy efficiency by multiple dimensions such as energy per unit of traffic, per connection, per cell site or per revenue.

ZTE advocates a multi-dimensional approach to evaluating network energy consumption and efficiency based on a combination of traffic, coverage, delay evaluation to traffic, energy consumption, user experience, and energy saving. This approach guides operators in developing energy-saving strategies for energy-efficient, service-bearing networks, the company says. The energy efficiency identification system must be continuously updated and adapted to the specific service focus in different scenarios in different phases of network development.

All in, the implementations of Super-N 2.0 high-efficiency PA, RF pooling solution, the 0-bit 0-watt modular architecture, and the introduction of base station native AI are poised to drive increasingly sustainable network infrastructure aligned with net-zero emission goals for the MNOs operating it. 

https://www.theregister.com//2024/05/23/building_cheaper_greener_5g_networks/