Backscatter communications for ultra-low-power IoT: from theory to applications

Internet-of-Things (IoT) is expected to connect tens of billions of devices anytime and anywhere and enable a wide range of services such as smart city, connected vehicles, and health care [1]. Recent advancements have driven the rapid growth of IoT in 5G technologies along with cloud- and edge-computing-enabled big-data analytics. However, one typical drawback of the existing IoT solution is the limited lifetime due to the massive number of IoT devices being powered by batteries with finite capacities. Therefore, keeping a large number of energy-constrained IoT devices alive poses a key design challenge. To this end, Backscatter Communication (BackCom) has emerged as a promising technology, allowing IoT devices to transmit data with low-power consumption. Moreover, its low-complexity design and small form factor make BackCom more attractive by realizing cost-effective IoT deployment. We organize the remainder of this chapter as follows. In Section 7.1, we provide fundamental knowledge for BackCom, including the basic principles, key design parameters, and standardization. Then, we summarize several BackCom networks in Section 7.2 and introduce several advanced emerging communication technologies redesigned for BackCom in Section 7.3. In Section 7.4, we explain several performance improvement methods of BackCom. Next, we focus on the applications empowered by BackCom in Section 7.5. Last, we discuss the open issues and future directions of BackCom in Section 7.6.