Coverage Analysis of NB-IoT and Sigfox: Two Estonian University Campuses as a Case Study

This paper presents the empirical results of the coverage analysis of two LPWAN technologies i.e. NB-IoT and Sigfox, conducted on university campuses in the two main cities of Estonia, i.e. Tartu and Tallinn, using the two commercially available NB-IoT operators and the single Sigfox operator in Estonia. Most of the existing literature on NB-IoT coverage is replete with RSSI-based coverage analyses. However, RSSI is most of the time not sufficient for evaluating LTE-based technologies including NB-IoT. Thus, our investigation of NB-IoT coverage considers three parameters: RSSI, RSRP, and RSRQ such that in situations where RSSI values are unavailable, the coverage analysis is based on RSRP and RSRQ. For Sigfox coverage, we base our analysis only on the RSSI factor, as Sigfox being a Non-LTE technology. Both technologies are evaluated in indoor, outdoor and deep-indoor/underground environments to provide an understanding of their coverage in various propagation and penetration conditions. Our results indicate that in outdoor scenarios, both Sigfox and NB-IoT achieve good to excellent coverage with almost 0% packet losses. However, in indoor scenarios, few packet losses were observed in Sigfox while no packet losses were observed in NB-IoT, even with a weaker coverage, and possibly due to re-transmissions that is a salient feature of NB-IoT, making it more reliable than its competitive LPWAN technologies. However, in deep-indoor or underground scenarios, coverage outages were recorded for NB-IoT, especially in Tartu area, indicating its weaker coverage in that city.