Evaluating the energy consumption savings at 450 MHz band for NB-IoT devices

In this paper, we empirically evaluate the energy consumption of Narrow-Band Internet of Things (NB-IoT) devices at emerging 450 MHz band targeted especially for critical communications. The evaluation was done at VTT’s private 5G and LoRaWAN networks by measuring the energy consumption of commercial NB-IoT and LoRa modules. Based on the results, operating at frequency band B31 (450 MHz) provides 4 to 11 dB gain in outdoor-to-indoor link budgets when compared to band B28 (700 MHz). This not only enables larger cells but also longer battery lifetime for cell edge devices which do not have to rely on coverage enhancement (CE) mechanisms so often. According to our measurements, B28 devices consumed 70% more energy at the cell edge than B31 devices. These are among the first published results from live NB-IoT B31 networks showing the energy saving potential from operating at the lowest standardized frequencies. In addition, the paper reviews the factors affecting the communications energy consumption for remote metering and provide valuable recommendations for practical implementation.