LAUSR

The Internet of Things (IoT) technology has attracted widespread attention since it can connect a huge number of heterogeneous devices to construct an intelligent environment to offer various services. Driven by the decreasing expense and significant convenience, it is expected that the total number of IoT devices will reach as high as 50 billion by 2020. And, these devices will provide diversified Internet services, including smart home, elder care, and vehicle-to-everything (V2X) communications. For the IoT technology, the network performance as well as the energy efficiency are both important since most end devices are battery limited. In this article, we focus on the IoT network based on the long-range wide-area network (LoRaWAN) protocol since its chirp modulation technology can adopt different spreading factors (SFs) to realize flexible communications. We propose a novel resource allocation strategy which utilizes multilayer virtual cell-based spatial time division multiple access (STDMA) scheme. This new method can not only simplify the calculation of the interference but also enables the cell radius to be adjusted to fit the communication distance. Moreover, the relationship between the power consumption and the network data rate is also analyzed in this article. We numerically analyze the optimal power consumption to achieve the highest data rate. The final performance evaluation demonstrates the significant improvement of our proposal compared with the conventional method.