Optimizing NB-IoT Power Consumption via Adaptive Radio Access

Narrowband Internet of Things (NB-IoT) standardized by the 3GPP has attracted significant attention since its appearance. It provides extended coverage, high capacity, reduced device processing complexity, and low-power consumption to meet the requirements of a wide range of IoT applications. In particular, NB-IoT is expected to bring IoT devices prolonged lifetime up to ten years. Radio access (RA) plays a key role in the total power consumption of NB-IoT devices. Specifically, the enhanced coverage levels (ECLs) configure the user equipment (UE) with different random-access resources and power consumption during packet transmissions. In this article, we examine the ECL selection strategies for reducing the power consumption of NB-IoT. We develop two testbeds to conduct extensive field measurements related to ECL selection. Based on the measurement results, we analyze the key issues in the ECL selection process. Then, we propose an adaptive RA approach for UE, which includes two novel strategies for predictive ECL selection and opportunistic packet transmission. Evaluations show that, with the configuration of ECL selected by our adaptive approach, the UE can reduce the radio power consumption up to 36% while maintaining the same block error rate (BLER) during uploading under real-world settings.