Researchers in Spain are presenting a step toward more sustainable power for wireless communications systems as well as Internet of Things (IoT) devices.
Developed by a team from IMDEA Networks Institute in Madrid (in collaboration with Uppsala University in Sweden), a new system—PassiveLiFi—uses light fidelity (LiFi)—a wireless communication technology that uses light to transmit data between devices—to transmit radiofrequency (RF) backscatter—a passive and low-energy transmission technique—“at a meager power budget.” The system is completely battery-free.
“Our work opens the door to long-range, battery-free Internet of Things applications [including] retrofitting lighting infrastructure for communication,” says Dr. Domenico Giustiniano, a research associate professor at IMDEA, where he leads the Pervasive Wireless System Group. “[This is] something that was not previously possible to achieve.”
Limitation hurdles
Traditionally, ambient RF backscatter, which uses “an incident radiofrequency signal to transmit data without a battery or power source,” comes with limitations and challenges, including a lack of control over RF power levels (as there is no internal RF source). And because the backscatter can collect just a small amount of electricity, it can only be utilized for a few devices and components. Also, ambient backscatter technology faces “severe security issues” due to dependency on external RF signals. Additionally, RF backscattering touts low data rates as well as a lower coverage range.
The researchers cite, too, an urgent need “to find a solution for removing batteries without affecting communication performance and IoT services,” as batteries and their chemical components “threaten to have a huge environmental impact on the Earth.”
The IMDEA team has shown that LiFi can solve those limitations. The study has essentially demonstrated that “power-constrained IoT devices can reach very long-range transmission without affecting their power consumption.”
“Our solution solves the trade-off between the captured energy required by the IoT device and the desired data rate, allowing our system to operate without using batteries,” says Borja Genovés Guzmán, a post-doctoral researcher at IMDEA and a co-author of the study. He adds that this research shows that light sources “can be used efficiently and simultaneously as both a source of power harvesting and as a communications receiver.”
With the new LiFi/RF backscatter combination paving the way for battery-free communication, it could lead to a number of IoT applications, including smart homes, smart cities, and smart agriculture.
