Green circuit design for battery-free sensors in cloud radio access network

Cloud radio access network (C-RAN) is considered as a promising approach to solve the bandwidth crunch problem for future wireless network. Another important element for future network is sensors that can monitor physical or environmental conditions. Currently, most sensors need batteries for power, which is energy-consuming and maintenance-heavy. To further improve energy efficiency (EE) of sensors in C-RAN, this paper proposes a new structure as well as practical circuit design for green sensors in C-RAN. The structure can enable sensors to harvest energy from radio signals transmitted by neighbor remote radio heads (RRHs) and user terminals (UTs). To demonstrate the validity of the new structure, a practical circuit design is suggested and the corresponding hardware platform is realized. Specifically, selection criteria for electrical component parameters and design of an impedance-matching network are discussed in details. In addition, two methods to stabilize the output voltage are proposed and analyzed. Finally, simulation results as well as experimental results are provided to corroborate our proposed studies.