A REVIEW OF INTEGRATED RADIO FREQUENCY ENERGY HARVESTING AND COGNITIVE RADIO FOR THE INTERNET OF THINGS

In recent decades, there has been significant growth in interconnected communication devices, with the Internet of Things (IoT) being one of the most intensively developed wireless communication appliances. This concept can be implemented in several areas, including smart cities, transportation, telemedicine, agriculture, and wearable applications. However, this increase in connectivity demand can lead to spectrum shortages in the future. In addition, in the development of future green communications, it is crucial to incorporate self-powered systems using energy harvesting technologies. In this review, it is shown that the integration of cognitive radio and radio frequency energy harvesting into IoT development can address the spectrum shortages and energy issues mentioned earlier. The findings indicate that the operating model works based on the slotted approach and state consideration, and the system’s performance metric can be optimised by adjusting parameters such as harvesting time, sensing time, transmit time, transmission power, interference level, and others. This review provides a comparative summary of several focus domains, such as RF harvesting, spectrum sensing and utilisation, operating models, and some open research issues for further work.