In February of 2019, the GSMA board set what it called a “milestone ambition”: The goal to transform the mobile industry so that it would reach net-zero carbon emissions by 2050 at the latest. An energy crisis in Europe, and climate-driven natural disasters and inflationary pressures around the world, are contributing to new urgency around reducing both energy costs and carbon dioxide emissions related to mobile networks—even as operators ramp up their work to meet mid- and long-term sustainability goals such as the one set by GSMA.
There is an obvious candidate for improvement: the RAN, which accounts for more than half of mobile network operators’ power consumption. Per Kangru, technologist in the Office of the CTO at VIAVI Solutions, offered up three strategies for operators to cut their energy use and the associated direct and indirect costs—strategies that also offer the possibility of better network performance.
Tuning RAN power levels. With appropriate tuning of network power levels by adjusting tilts and fully or partially powering off cells, Kangru said, operators can rapidly see a 5% reduction in energy costs, while maintaining or improving performance quality. Since network operators account for roughly 1% of all electricity usage globally, “five percent savings of 1% total is quite a significant total number,” Kangru said. “The value of that is quite high.” Operators must find a balance here: After all, a network can’t provide services if the power levels are turned too far down. How should operators balance that tuning? By leveraging fine details from mobility data along with geolocation intelligence, Kangru says. Such information can be fed into an ML-driven digital twin to quantify the impacts on energy savings while protecting customer experience and ensure that RF energy isn’t directed to areas where there are no users. By adjusting network power levels more effectively, operators can accomplish two goals at once: Cut energy use and potentially boost performance.
Train more intelligent RAN systems. There is ecosystem-wide work happening in Open RAN that is pushing forward with development, testing and optimization of xApps and rApps for O-RAN that will drive energy saving features, Kangru notes. Operators such as Deutsche Telekom, Orange, Telefónica, TIM and Vodafone have made energy efficiency a stated technological priority of their Open RAN collaborations — for example, RAN Intelligent Controller (RIC)-based functions that could use AI/ML to activate and deactivate sleep mode functions, or enable energy-aware traffic steering to specific bands. Kangru offers up one specific example that VIAVI has developed: Emulation of real-world cells, energy usage, and subscriber movements in the lab, in order to train the RIC to operate within an optimized energy and QoE window.
“Many of those algorithm solutions are not only O-RAN-based, but they could be applied to existing radio access networks,” Kangru says.
Better installation. The “good enough” installation of a cell site is no longer good enough when operators want to save energy. For example, antenna installations have been guided with a digital compass that achieves approximate, but not precise, accuracy. “People would accept a certain amount of imperfection, simply because it was good enough,” Kangru says. “If antenna alignment is a few degrees off, the network will still deliver sufficient quality of coverage. But you’re wasting energy, and you’re adding incremental inter-cell interference. So when you want to do interference mitigation, and when you want to do energy savings, the level of precision in antenna installation becomes really important.” Kangru also observed that, beyond the RAN, VIAVI has seen significant energy usage reduction and performance improvements achieved in the wireline access network through more intelligent installation and maintenance. The company is working with a network operator in the U.K. on a new methodology for validating and maintaining their fiber network, which has reduced truck-rolls by 5,000 per week. Kangru called that scenario “the best kind of energy savings: When it’s not consumed.”
Using intelligent tools for more precise network installations that both minimize energy consumption and deliver the performance parameters expected from network planning, ultimately means a network that functions more efficiently. And that is important for not just individual operators, but the industry as a whole, Kangru says.
“The key is for the entire industry, so that we can better manage energy activity locally, regionally and globally,” he adds. After all, Kangru pointed out, energy prices in most of the world are set based upon the last kWh consumed—so reducing energy usage on a local basis, to avoid hitting peak demand that adds surge pricing, can reduce topline costs by as much as half. This is particularly crucial in Europe, where users are facing energy costs as much as ten times higher than what they paid a year ago. “Each of those saved kWh becomes really important,” he says.
Visit VIAVI at MWC Barcelona 2023 for a demonstration of end-to-end RAN energy savings solutions. More information at www.viavisolutions.com/mwc23
