Abstract
As sub-GHz wireless Internet of Things (IoT) sensor networks set the stage for long-range, low-data-rate communication, wireless technologies such as LoRa and SigFox receive a lot of attention. They aim to offer a reliable means of communication for an extensive amount of monitoring and management applications. Recently, several studies have been conducted on their performance, but none of these feature a high dynamic range in terms of channel measurement. In this contribution an autonomous, low-power, LoRa-compatible wireless sensor node is presented. The main uses for this node are situated in LoRa channel characterization and link performance analysis. By applying stepped attenuators controlled by a dynamic attenuation adjustment algorithm, this node provides a dynamic range that is significantly larger than what is provided by commercially available LoRa modules. The node was calibrated in order to obtain accurate measurements of the received signal power in dBm. In this paper, both the hardware design as well as some verification measurements are discussed, unveiling various LoRa-related research applications and opportunities.
Highlights
Wireless sensor networks (WSNs) are at the heart of the ever-developing Internet of Things (IoT)
Seeing WSN deployment over larger and larger areas, it becomes evident to consider the use of sub-GHz frequency bands for communication in these long-range networks, given the superior propagation characteristics when compared to higher frequency bands
Given that the LoRa module has a linear signal-to-noise ratio (SNR) measurement range corresponding to a signal level range of 32 dB, a simple calculation reveals that the use of attenuators at the receiver’s side of the link increases the node’s theoretical dynamic range for signal measurements to 63.5 dB
Summary
Wireless sensor networks (WSNs) are at the heart of the ever-developing Internet of Things (IoT). The middle ground can be found by integrating a commercially available LoRa module into a system with more capabilities to create a compact, low-power wireless sensor node. In this paper, such a node is proposed, designed and tested. To verify the correct operation of the node, several experiments were carried out in and around the city of Ghent, Belgium
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