Energy Efficiency of Open Radio Access Network: A Survey.

The Open Radio Access Network (O-RAN) architecture has been identified as a promising technology for enhanced network deployment, innovation, improved competition, and reduction of capital and operating expenses (CAPEX/OPEX) of 5G and beyond networks because of its open interfaces, disaggregated network entities and functions, virtualization of network hardware and software, and intelligent control. However, the effect of this improved technology on the energy consumption of the RAN needs to be carefully investigated, so that the many advantages that can be obtained from the O-RAN are not overwhelmed by increased energy consumption. Hence, in this paper, we investigate the O-RAN from an Energy efficiency (EE) perspective by reviewing the state-of-the-art power consumption models, and EE techniques that have been proposed to minimize the energy consumption of O-RAN. In addition, the challenges associated with the optimization of the EE of O-RAN and opportunities for further research are highlighted.