Wireless energy transfer policies for cognitive radio based MAC in energy-constrained IoT networks

Efficient energy transfer is crucial for a green base station with limited energy to replenish the energy of stand-alone devices in the Internet of Things (IoT). Cognitive radio (CR) is critical to satisfying the spectrum requirement for IoT devices. This paper proposes two wireless charging policies, namely, charging in residual multi-frame time and charging one energy unit at a time, for the random access multiple access control on CR-based green-energy networks. The novelty of the policies is to send wireless energy at appropriate timing and duration. Event-driven simulations are conducted to study the performances of the policies. Simulation results show that the two policies significantly yield high energy efficiency, and maintain throughput and quality-of services. Besides, the policy of charging one energy unit at a time outperforms the policy of charging in residual multi-frame time.