Potential transmission choice for Internet of Things (IoT): Wireless and batteryless communications and open problems

The 5th generation mobile communications aims at connecting everything and future Internet of Things (IoT) will get everything smartly connected. To realize it, there exist many challenges. One key challenge is the battery problem for small devices, such as sensors or tags. Batteryless backscatter, also referred to as or battery-free backscatter, is a new potential technology to address this problem. One early and typical type of batteryless backscatter is ambient backscatter. Generally, batteryless backscatter utilizes environmental wireless signals to enable battery-free devices to communicate with each other. These devices first harvest energy from ambient wireless signals and then backscatter these signals so as to transmit their own information. This paper reviews the current studies about batteryless backscatter, including various backscatter schemes and theoretical works, and then introduces open problems for future research.