Boosting the Long Range Sensing Potential of LoRa.

Wireless sensing is capable of capturing rich information of human target without requiring sensors attached to the target. Although promising, two critical issues still exist, i.e., (i) limited sensing range, and (ii) severe interference in real-world settings. Recently, LoRa is employed to improve the sensing range. Although LoRa sensing is able to achieve a longer sensing range than WiFi and acoustic sensing, it is still limited to tens of meters. In this paper, we propose ChirpSen , which fully exploits the property of chirp signal to increase the sensing range. ChirpSen adopts a chirp concentration scheme to concentrate the power of all signal samples in a LoRa chirp at one timestamp, improving the signal power and accordingly boosting the sensing range. With a longer sensing range, the interference issue also becomes more severe. We propose a novel scheme to flexibly control the sensing coverage by tuning the LoRa chirp length in software. Real-world experiments show that ChirpSen is able to increase the detection range of a small size drone (12 cm × 10 cm × 8 cm) from 18 m to 160 m. ChirpSen is capable of monitoring a human's respiration rate at 138 m and tracking a human target's walking trajectory 210 m away.