Energy Modeling and Evaluation of NB-IoT with PSM and eDRX

Large-scale deployment and management of Internet of Things (IoT) devices will become a critical issue in the near future. The 3rd Generation Partnership Project (3GPP) has proposed NarrowBand - Internet of Things (NB-IoT) as a new radio technology standard to enable Internet connectivity for a massive number of low-throughput devices. It supports better coverage and lower energy consumption than traditional Long-Term Evolution (LTE). The NB-IoT specification adopts the Power Saving Mode (PSM) and Extended Discontinuous Reception (eDRX) mechanisms to achieve a long battery life. In this paper, we present an energy consumption model for NB-IoT devices using PSM and eDRX, with a Poisson arrival process for uplink and downlink data transmissions. The model is compared to NS-3 simulation results. We analyze NB-IoT energy consumption for different PSM timers, eDRX timers and packet Inter-Arrival Times (IATs) based on the proposed model. Additionally, we have simulated the battery life for an NB-IoT use case on tracking shared bicycles. Comparison of the analytical model and simulation results shows consistency in the results with an average error of 11.82%. Our results also showed that with a 5 Wh battery, a device lifetime of more than 12 years can be achieved when transmitting at most one packet per day, and when properly confiauring the PSM and eDRX timers.