1. PassiveLiFi: Rethinking LiFi for Low-Power and Long Range RF Backscatter
- Author
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Muhammad Sarmad Mir, Borja Genoves Guzman, Domenico Giustiniano, and Ambuj Varshney
- Subjects
VLC ,Backscatter ,business.industry ,Computer science ,Transmitter ,Electrical engineering ,Chirp spread spectrum ,Power budget ,Power (physics) ,Telecommunications link ,RF backscatter ,Systems design ,business ,Energy (signal processing) ,LiFi - Abstract
Light bulbs have been recently explored to design Light Fidelity (LiFi) communication to battery-free tags, thus complementing Radiofrequency (RF) backscatter in the uplink. In this paper, we show that LiFi and RF backscatter are complementary and have unexplored interactions. We introduce PassiveLiFi, a battery-free system that uses LiFi to transmit RF backscatter at a meagre power budget. We address several challenges on the system design in the LiFi transmitter, the tag and the RF receiver. We design the first LiFi transmitter that implements a chirp spread spectrum (CSS) using the visible light spectrum. We use a small bank of solar cells for communication and harvesting and reconfigure them based on the amount of harvested energy and desired data rate. We further alleviate the low responsiveness of solar cells with a new low-power receiver design in the tag. Experimental results with an RF carrier of 17 dBm show that we can generate RF backscatter with a range of 80.3 meters/𝜇W consumed in the tag, which is almost double with respect to prior work. European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 814215 TRUE inpress
- Published
- 2021