DORM: Narrowband IoT Development Platform and Indoor Deployment Coverage Analysis

Abstract The development of DORM (integrateD cOmpact naRrowband platforM) node is presented that combines low cost and low power components in a multi-layer architecture to support versatile NB-IoT applications. In our proposed DORM node, the processing component provides an interface to a variety of sensors and the radio component provides connectivity to the IoT cloud as required by IoT applications. Furthermore, an overview of our NB-IoT test network is presented that is deployed at Tallinn University of Technology (TalTech) campus, Estonia with a detailed description of its various functionality layers. In addition, an in-field investigation of the coverage of our NB-IoT system is made whereby our DORM nodes are deployed across the TalTech campus so as to explore its connectivity performance and possible issues in an indoor scenario. We made empirical measurements on NB-IoT coverage for different elevation levels, a key performance indicator that most of the operators would be interested in. We obtained averaged SNR and RSSI values in the range of 18 dB to 23 dB and -65 dBm to -70 dBm, respectively. Our obtained results show that our NB-IoT system provides an excellent connectivity in indoor environments and can satisfy IoT application requirements. However, small variations in these SNR and RSSI values are observed at different elevation levels possibly due to positioning of the measuring nodes, proximity of the antenna with respect to the base-station, building structure and its construction material and the surrounding environment of the placement of our DORM nodes.