Contents Introduction
Information transmission based on modulated backscatter of incident signals from external RF sources has emerged as a promising solution for low-power wireless communications. The power consumption of a typical backscatter transmitter is less than [1], which renders excessively long lifetime, e.g., 10 years for an on-chip battery. This low power consumption well matches the harvestable wireless energy from RF sources, e.g., typically from to tens of [2]. This additionally renders RF energy harvesting to be an alternative to power backscatter transmitters. Furthermore, backscatter communications can be embedded into small gadgets and objects, for example, a radio frequency identification (RFID) and passive sensor. Therefore, backscatter communications are also envisioned as the last hop in the Internet-of-Things (IoT), which requires low cost and ubiquitous deployment of small-sized devices.
