New backscatter technology promises cost-effective reliability
Traditional bi-directional wireless communication requires both a receiver and a transmitter at either end. Your laptop, for example, needs to receive a signal from your Wi-Fi router, but it also needs to transmit a signal back to that router. That transmission requires power proportional to the strength of the signal, which is less than ideal for many applications. Backscatter presents an alternative and UniScatter is new backscatter technology developed by a team of UC San Diego engineers that promises cost-effective reliability.
Backscatter communication works by reflecting a signal emitted by the receiver. But in order for that reflected signal to carry information, the reflector (the backscatter “tag”) needs to be able to introduce some form of modulation. That might information might be as simple as a static identifier, but it can be dynamic as well. A self-driving car could, for example, read backscatter tags on road signs with information as simple as a speed limit or something more complex like the state of a traffic light.
UniScatter utilizes metamaterials, like graphene, to enable more reliable backscatter reflections. It also adopts frequency shift keying (FSK), as opposed to amplitude shift keying (ASK), for modulation. For that to work, the UniScatter tag needs to alter the voltage bias of the graphene capacitor to control the backscatter reflection. UniScatter’s developers used an Arduino Due board to provide that modulation control.
In their research, UniScatter’s developers determined that this system works reliably from 20GHz to 90GHz. That allows for a lot of flexibility in system design and also ensures that communication remains stable across a wide variety of ambient conditions and physical orientations.
Images credit: K. Qian et al.