With the increasing digitalization worldwide, the demand of information also increases in all areas. MoleNet is a low-power sensing platform which is easy to assemble and use. It offers several options to monitor, for example, the soil moisture and temperature and visualize the data. Several researchers from different countriesare currently working and improving MoleNet for different applications. This demoshows the main application of MoleNet: Monitoring soil conditions in a remote area,transmitting the data and visualizing the current status

Dede, Jens

Förster, Anna

Helms, Daniel

English

Electronic Communications of the EASST (European Association of Software Science and Technology)

Electronic Communications of the EASSTVolume 080 (2021)Conference on Networked Systems 2021(NetSys 2021)MoleNet:An Underground Sensor Network for Soil MonitoringJens Dede, Daniel Helms and Anna Förster4 pagesGuest Editors: Andreas Blenk, Mathias Fischer, Stefan Fischer, Horst Hellbrueck, OliverHohlfeld, Andreas Kassler, Koojana Kuladinithi, Winfried Lamersdorf, Olaf Landsiedel, AndreasTimm-Giel, Alexey VinelECEASST Home Page: http://www.easst.org/eceasst/ ISSN 1863-2122ECEASSTMoleNet:An Underground Sensor Network for Soil MonitoringJens Dede1, Daniel Helms2 and Anna Förster3jd@comnets.uni-bremen.dedhelms@uni-bremen.deanna.foerster@uni-bremen.deSustainable Communication NetworksUniversity of Bremen, GermanyAbstract: With the increasing digitalization worldwide, the demand of informationalso increases in all areas. MoleNet is a low-power sensing platform which is easy toassemble and use. It offers several options to monitor, for example, the soil moistureand temperature and visualize the data. Several researchers from different countriesare currently working and improving MoleNet for different applications. This demoshows the main application of MoleNet: Monitoring soil conditions in a remote area,transmitting the data and visualizing the current status.Keywords: sensor network, underground communication, WUSN, soil monitoring1 IntroductionMoleNet [ZDG+16] was originally developed for monitoring reforestation projects in developingcountries. Here, a long time monitoring of the soil properties in remote areas is required. Thespecial requirements 1) long battery lifetime (i.e., several years), 2) inexpensive devices, 3) easyto build, set up, and maintain and 4) data transmission between the buried nodes was not achievedby existing systems. Therefore, we decided to develop a new system tailored to those needs. Inthe beginning, our focus was mainly on the subsurface communication challenges [HSW+20]and the soil water content [AS06]. Meanwhile, the use cases of MoleNet evolved, and the systemwas also evaluated for additional projects like, for example, for monitoring fish tanks [QZF20]or finding trapped miners [ZFMC18].In this demo, we show data from one of our currently running field tests where the soil ismonitored at a local farm.2 System OverviewMoleNet is based on standard technologies and can be adapted easily. Figure 1 shows the princi-ple setup of a MoleNet measurement site. 1 is the sensor network itself containing the MoleNetnodes with different sensors attached. Those nodes are battery powered and communicate using433MHz radio technology. Depending on the setup, the nodes can be buried and operate severalmonth to years without maintenance or battery changes. 2 shows the MoleNet base station.Here, also data can be collected like from an optional weather station 3 . The main task of the1 / 4 Volume 080 (2021)MoleNetFigure 1: The Infrastructure of the demo setup: The measured data is transmitted from theMoleNet nodes to the end-user device.MoleNet base station is to receive the data from the nodes and forward it to the Internet. For that,the collected data is sent via long-range communication technologies 4 like a cellular network,WiFi, or LoRaWAN to the corresponding infrastructure, or more precisely, to the base station ofthe service 5 . From here, the data is sent to one or several Internet services for storage, furtherprocessing and user access 6 .3 Sensor Node HardwareMoleNet is an open-source project and available on github1. The design is based on Arduino2with the focus on very low power consumption. Arduino ensures that a complete ecosystem ofdocumentation, tutorials, drivers, and libraries can easily be integrated. Especially for begin-ners in embedded programming and system design, MoleNet offers a good starting point forlow-power open-source hardware. For the same reason, we decided to focus on easy-to-solderstandard components.Figure 2 shows the PCB of a node. The main parts are 1 the microcontroller, which isrunning the program itself, 2 an RTC (clock) module ensuring precisely timed measurementsand wakeups, 3 a radio module for the communication with other nodes and the base station,4 a flash memory for data storage, 5 a connector for the sensors and 6 the antenna.The current system operates at 433 MHz but can be adapted easily to other frequencies or evencommunication standards.MoleNet is optimized to a low power consumption between two consecutive sensor readings.For most applications, only a few measurements per day or even less are required. This allows toshut down the system, including most peripheral, and only keep the RTC module running. Aftera certain period of time, the RTC wakes up the system, starts the measurement, saves the dataon the flash memory, starts the data transmission, and returns to the deep sleep mode. In anotherconfiguration, the node enters the deep sleep mode after saving the data and transmits the data1 https://github.com/ComNets-Bremen/WUSN2 https://arduino.ccNetSys 2021 2 / 4ECEASSTFigure 2: A MoleNet sensor node.only once a day, further decreasing the power consumption.4 MoleNet ApplicationsEven if the main application area of MoleNet is soil monitoring, we have already used it forvarious other applications and further are in planning. The MoleNet platform is very well suitedfor challenged environments in general, where communications at higher frequencies are impos-sible. We have used MoleNet for fish tank monitoring in Namibia [QZF20], where the sensornodes are deployed on the edge of the fish tanks, with sensors hanging into the water and mon-itoring salt levels, dissolved oxygen, temperature, and pH values. In South Africa [ZFMC18],we have used MoleNet to develop a system for localizing trapped miners after a mine collapse.Here, no sensors were used at all, and only the radio signal strength was utilized to localise thesensor nodes, carried by miners.5 Planned DemoFor the demo, we plan to show live data from two sources: Soil measurements from a field innorthern Germany and live data collected at the venue. The data will be transmitted using thesystem as shown in Figure 1 and displayed on a webpage similar to Figure 3. The impact of rainon soil moisture and the power consumption of the system will be demonstrated.6 Conclusion and Future WorkMoleNet offers an inexpensive, easy-to-build, use and maintain low-power sensor node platform.It is flexible to use and offers a good starting point, especially for newcomers in embeddedhardware and programming.3 / 4 Volume 080 (2021)MoleNetFigure 3: Example data from a measurement: The air temperature above the surface (red) andthe raw values of the moisture sensor (green) are shown.Due to the variety of different users and applications, their expectations and requirements ofthe project, the future work is manifold. One focus is to extend the MoleNet nodes to a moremodular system: Adding new sensors with different hardware interfaces is currently simplified.Regarding the hardware, we are evaluating the recent developments in chip design and plan toadapt the system to newer generations of low-power microcontrollers. Furthermore, in the nearfuture, tutorials and videos will be made available on our youtube channel to foster the usage ofMoleNet in education. Everybody is invited to contribute to the MoleNet project on github or onthe project webpage: https://www.molenet.org.Bibliography[AS06] I. F. Akyildiz, E. P. Stuntebeck. Wireless underground sensor networks: Researchchallenges. Ad Hoc Networks 4(6):669–686, 2006.doi:10.1016/j.adhoc.2006.04.003[HSW+20] H. Huang, J. Shi, F. Wang, D. Zhang, D. Zhang. Theoretical and experimental stud-ies on the signal propagation in soil for wireless underground sensor networks. Sen-sors 20(9):2580, 2020.doi:10.3390/s20092580[QZF20] K. Qayyum, I. Zaman, A. Förster. H 2 O Sense: a WSN-based monitoring systemfor fish tanks. SN Applied Sciences 2(10):1–12, 2020.doi:10.1007/s42452-020-03328-3[ZDG+16] I. Zaman, J. Dede, M. Gellhaar, H. Koehler, A. Foerster. Molenet: A new sensornode for underground monitoring. IEEE SenseApp, 2016.[ZFMC18] I. Zaman, A. Förster, A. Mahmood, F. Cawood. Finding trapped miners with wire-less sensor networks. In 2018 5th International Conference on Information andCommunication Technologies for Disaster Management (ICT-DM). Pp. 1–8. 2018.doi:10.1109/ICT-DM.2018.8636376NetSys 2021 4 / 4

MoleNet: An Underground Sensor Network for Soil Monitoring

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MoleNet: An Underground Sensor Network for Soil Monitoring

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