An Evaluation of RAN Sustainability Strategies in Production Networks

Reducing energy consumption is a primary goal for the mobile telecommunication industry, with strong environmental and economic implications. The main target for savings is the Radio Access Network (RAN), which is responsible for more than 70% of the total energy costs incurred by operators. Lowering energy costs at the RAN is possible by reducing the number of active carriers at off-peak locations and times where the demand can be served with a lower capacity than deployed. While the scientific community has been proposing a plethora of complex solutions to switch-off underutilized carriers, production networks largely rely nowadays on threshold-based strategies that run at individual RAN equipment and are typically enabled only overnight. Moreover, there are no real-world evaluations of the effectiveness of carrier switch-off approaches in reducing energy consumption or their impact on the end users. In this paper, we benchmark five fixed threshold-based cell sleep policies deployed in a production network serving large geographical regions. The study provides unprecedented insights on industry-grade RAN sustainability at scale, in terms of actual energy savings and trade-offs with user experience. Our insights suggest that the capability of the tested policies in reducing the energy costs hits a clear barrier if no degradation is admissible for any user, and provides a strong empirical basis in support of more flexible approaches to save energy at the RAN.