1 research outputs found
A Retrodirective Wireless Power Transfer Scheme for Ambient Backscatter Systems
One of the key challenges of the Internet of Things (IoT) is to sustainably
power the large number of IoT devices in real-time. In this paper, we consider
a wireless power transfer (WPT) scenario between an energy transmitter (ET)
capable of retrodirective WPT and an energy receiver (ER) capable of ambient
backscatter in the presence of an ambient source (AS). The ER requests WPT by
backscattering signals from an AS towards the ET, which then retrodirectively
beamforms an energy signal towards the ER. To remove the inherent direct-link
ambient interference, we propose a scheme of ambient backscatter training.
Specifically, the ER varies the reflection coefficient multiple times while
backscattering each ambient symbol according to a certain pattern called the
training sequence, whose design criterion we also present. To evaluate the
system performance, we derive an analytical expression for the average
harvested power at the ER. Our numerical results show that with the proposed
scheme, the ER harvests tens of W of power, without any CSI estimation or
active transmission from the ER, which is a significant improvement for
low-power and low-cost ambient backscatter devices.Comment: Accepted to appear in IEEE ICC 2020. arXiv admin note: substantial
text overlap with arXiv:1909.0063