A Compact Low-Power LoRa IoT Sensor Node with Extended Dynamic Range for Channel Measurements

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.

Experimental Parameter Optimization for Adaptive LoRa Modulation in Body-Centric Applications

“…The wireless nodes applied to characterize the body-centric LoRa link are based on the custom-built research-oriented LoRa platform described in [12]. One of these nodes serves as a base-station.…”

Indoor Body-to-Body LoRa Link Characterization

“…To probe the indoor channel, two custom-built wearable LoRa nodes are used. These nodes consist of a compact, lowpower LoRa system with extended dynamic range for performing channel measurements [4], integrated on a substrate integrated waveguide textile antenna [5]. Each node is powered using a low-profile LiPo battery, which is also integrated on the antenna.…”

“…Statistical performance data of the channel under investigation are always based on the measurements gathered when using the most sensitive dynamic range settings. However, to create graphical representations of the received power and calculate average values, packets that saturated the receiver are omitted in favor of those packets that were received with a dynamic range shifted up by using the on-board RF-attenuators, as was thoroughly described in [4]. In all experiments, packets are transmitted with a transmission power of 10 dBm.…”

“…To assess the performance of such a system, a custombuilt LoRa node [4] was integrated on a wearable substrateintegrated-waveguide (SIW) antenna [5]. By transmitting very short packets with a low LoRa spreading factor, a decent repetition rate can be achieved to probe channels and characterize off-body wireless links.…”

Implementation of embedded real-time monitoring temperature and humidity system

“…The wired system method had many disadvantage as compared with wireless method. Among the wireless system used to implement real time monitoring are Global System for Mobile (GSM), Wireless Fidelity (WIFI) [9], [10] and Low Power Wide Area Network (LoRaWAN) [11], [12]. Each of these technologies has its own advantages over the other that depends on the requirement and deployment scenarios.…”