Poster: Low-complexity Outdoor Localization for Long-range, Low-power Radios

Abstract

The newly introduced LPWA radios, with their longdistance connectivity and low-power characteristics are becoming a viable option for interconnecting many IoT devices. For applications that seek kilometer-level connectivity, LPWA (e.g., LoRaWAN [1]), with narrowband radios and low reception sensitivity, can help meet their systemlevel requirements. Given their deployments over wide-areas we find LoRa device localization as an interesting research topic. Our preliminary experiences with the Semtech SX1272 LoRa radio shows a long-tail RSSI trace trend. Specifically, RSSI values at the 20 km distance and 30 km distance only shows a difference of 3-6 dBm, which is within typical fluctuation ranges. Besides using RSSI, we can also utilize the propagation delay of wireless signals for localization. Given that the communication range spans over multiple kilometers, receivers at distant locations can observe noticeable differences in the signal reception time for a packet signal from a transmitter. Our scheme utilizes time-of-arrival (ToA) measurements gathered from multiple anchor points for estimating a target device’s location using a low-complexity divide-andconcur method.