Researchers Use LoRa Radios for Long-Range Through-Wall Respiration, Movement Tracking
Following work done on short-range through-wall tracking via reflected Wi-Fi signals, the same has now been achieved with LoRa at up to 30m.
Researchers from the University of Massachusetts, University of Colorado Boulder, Peking University, the Chinese Academy of Sciences, and the Institut Polytechnique de Paris have demonstrated how LoRa radio signals can be used for through-wall sensing at long ranges — in much the same way as Wi-Fi has been used over shorter distances.
"Wireless signals have been extensively utilized for contactless sensing in the past few years. Due to the intrinsic nature of employing the weak target-reflected signal for sensing, the sensing range is limited," the team explains in the paper's abstract. "For instance, Wi-Fi and RFID can achieve 3-6 meter sensing range while acoustic-based sensing is limited to less than one meter.
"In this work, we identify exciting sensing opportunities with LoRa, which is the new long-range communication technology designed for IoT communication. We explore the sensing capability of LoRa, both theoretically and experimentally."
To prove the concept, the team built a prototype sensing system which paired a transmitter based on a Semtech SX1276 LoRa radio connected to an Arduino Uno microcontroller with a dual-antenna gateway based on an off-the-shelf laptop with a USRP B210 software-defined radio and the open source GNU Radio software.
"Experimental results show that (1) human respiration can still be sensed when the target is 25 meters away from the LoRa devices, and 15 meters away with a wall in between," the team found, "and (2) human walking (both displacement and direction) can be tracked accurately even when the target is 30 meters away from the LoRa transceiver pair."
The full paper is available under open-access terms following its presentation at the ACM International Joint Conference on Pervasive and Ubiquitous Computing 2020 (UbiComp '20).