Power Utilization in Open RAN: Key Findings From a USA Testbed

Open Radio Access Networks (Open RAN) provide flexible, scalable, and interoperable solutions to address the growing demands of mobile traffic while also aiming to reduce energy consumption. Most prior research on energy-efficient Open RAN has focused on switching techniques such as dynamic cell on/off strategies and adaptive resource allocation, primarily through simulations. This letter investigates Central Processing Unit (CPU) power utilization at the NodeB (base station) level, focusing on User Equipment (UE) connection states by making use of a USA testbed (i.e., POWDER testbed). Two scenarios are considered for the experimental setup: (1) a simulated virtual environment with a single high-powered device and (2) a physical hardware deployment using the separate low-power device for Open RAN. We present key findings from simulated and physical NodeB experiments conducted on the USA testbed, with real hardware. The findings include the relationship between power utilization and forced throughput, the impact of an increasing number of UEs on power utilization, the effects of different UE connection states (active, idle, or not connected), and the behavior of uplink and downlink throughput in both simulated and physical setups. Additionally, this letter introduces and validates power-law equations for power utilization in both setups, offering valuable insights into the effectiveness of UE connection state switching on NodeB CPU power utilization pattern. These findings contribute to the development of strategies for achieving energy-saving objectives in Open RAN.