NB-IoT Network Field Trial: Indoor, Outdoor and Underground Coverage Campaign.

Recent advancements in cellular technologies allow discrete computing devices embedded with sensors to communicate over long distances with low-cost and low-energy consumption. This could drastically impact the future internet of thing (IoT) ecosystem. In this regard, Third Generation Partnership Project (3GPP) has introduced a new cellular-based technology called Narrowband Internet of Things (NB-IoT) which is one of the potential technologies for enabling IoT application in vehicular, health-care, industry 4.0, etc. However, NB-IoT technology is still in its infancy and so far it is unclear whether it is sufficiently reliable to complement or replace existing short-range and cellular technologies to enable such use-case scenarios. Therefore, this paper presents a preliminary investigation of the coverage of NB-IoT in three different scenarios i.e., outdoor, indoor, and underground with empirical measurements, one of the key performance indicators in which operators are most interested. The measurements were conducted on Tallinn University of Technology (TalTech) campus and nearby residential areas within a range of 700 m. The obtained results indicate that NB-IoT is able to provide good connectivity to meet the IoT application requirements in outdoor and indoor environments. However, for an underground scenario with the beam enabled for 700 m, it is only possible to provide connectivity to the devices up to 400 m. Furthermore, it is also observed that NB-IoT is able to provide connectivity to devices with a received signal strength indicator (RSSI) value as low as −105 dBm as compared to −95 dBm as in long-term evolution (LTE).