Coverage Analysis of LPWAN in Estonia: Sigfox and NB-IoT Case study in Tallinn and Tartu

Abstract

Low Power Wide Area Networks (LPWANs) have become an important technology for the Internet of Things, as they provide radio coverage in the order of kilometers and enable battery-powered devices to operate for years. This thesis presents the in-depth technical overview along with results of an in-field investigation of the coverage analysis of two LPWAN technologies i.e., NB-IoT and Sigfox, conducted in Tartu and Tallinn. The observations are taken for the time span of 12-24 hours with the evaluation boards using NB-IoT sim-cards by two commercially available NB-IoT operators (Telia and Elisa) and the single Sigfox operator in Estonia. Most of the existing literature on NBIoT coverage is replete with Received Signal Strength Indicator (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, Reference Signal Received Power (RSRP), and Reference Signal Received Quality (RSRQ). Sigfox, being a non-LTE technology, we base our coverage analysis only on the RSSI factor. Both technologies are evaluated in indoor, outdoor and deep-indoor/underground environments so as 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 the 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.