Channel Access Methods for RF-Powered IoT Networks: A Survey

Devices in Internet of Things (IoT) networks are likely to operate over a shared medium, and thus they have to use a channel access protocol to minimize or avoid collision. Further, they may have to harvest radio frequency (RF) energy in order to transmit or/and receive data. To this end, this survey presents the first comprehensive review of prior works that employ contention-based and contention-free protocols in IoT networks with one or more dedicated RF energy sources. Specifically, these protocols work in conjunction with RF-energy sources to deliver energy delivery or/and data. In this respect, this survey covers protocols based on Aloha, carrier sense multiple access (CSMA), polling, and dynamic time division multiple access (TDMA). Further, it covers protocols that assume a receiver with successive interference cancellation capability. It highlights key issues and challenges addressed by prior works, and provides a qualitative comparison of these works. Finally, it identifies gaps in the literature and presents a list of future research directions.