Energy Harvesting Cognitive Radios

Energy harvesting can be combined with cognitive radios (CRs) to provide energy‐ and spectral‐efficient wireless communications. This chapter discusses different energy harvesting CR systems, and describes several important technical challenges in energy harvesting CR. It is necessary to explain how the conventional CR and its spectrum sensing function work, as they are also part of the principles based on which energy harvesting CR works. Depending on the spectrum sharing policies, there are three different types of CR systems: interweave; underlay; and overlay. In the overlay CR system, the CR user has full cooperation with the primary user. What makes CR unique is its spectrum sensing function. The chapter explains the energy harvesting CR systems that harvest energy from the secondary base station. It shows a diagram of the energy harvesting CR systems that harvest energy from the ambient environment.