  Localization is important for a large number of Internet of Things (IoT)
endpoint devices connected by LoRaWAN. Due to the bandwidth limitations of
LoRaWAN, existing localization methods without specialized hardware (e.g., GPS)
produce poor performance. To increase the localization accuracy, we propose a
super-resolution localization method, called Seirios, which features a novel
algorithm to synchronize multiple non-overlapped communication channels by
exploiting the unique features of the radio physical layer to increase the
overall bandwidth. By exploiting both the original and the conjugate of the
physical layer, Seirios can resolve the direct path from multiple reflectors in
both indoor and outdoor environments. We design a Seirios prototype and
evaluate its performance in an outdoor area of 100 m $\times$ 60 m, and an
indoor area of 25 m $\times$ 15 m, which shows that Seirios can achieve a
median error of 4.4 m outdoors (80% samples < 6.4 m), and 2.4 m indoors (80%
samples < 6.1 m), respectively. The results show that Seirios produces 42% less
localization error than the baseline approach. Our evaluation also shows that,
different to previous studies in Wi-Fi localization systems that have wider
bandwidth, time-of-fight (ToF) estimation is less effective for LoRaWAN
localization systems with narrowband radio signals.
