Department Urban Water Management

In-Sewer LPWAN - A new LoRa-based synchronous mesh network to help monitoring in-sewer processes

Motivation: Collecting real-time information on system dynamics is essential for identifying, predicting, and managing critical loading situations in urban drainage networks, such as urban flash floods and sewer overflows. Emerging low-power wireless communication techniques such as LoRaWANTM [1] allow now sparse and efficient data transfers with great aboveground performance. However, a large coverage range is difficult to achieve for underground or indoor applications, particularly in dense urban areas.

Development: Together with researchers from the ZHAW Winterthur (InES), we developed a novel LPWAN concept based on the LoRa® technology [2]. The new concept i) enhances transmission reliability, efficiency and flexibility in range-critical situations through meshed multi-hop routing, and ii) ensures a precise time-synchronization through optional GPS or DCF77 long-wave time signaling. It is extremely sparse and energy efficient and hence lays out the fundament for energy self-sufficient monitoring applications.

Use: In the UWO monitoring initiative, this new development allows us to communicate data wirelessly from sewer manholes at which we previously did not manage to transmit any data. Eleven prototypes are successfully in operation in the UWO since late 2018.

Availability: Source code and hardware specification is made freely available [3]. License: GNU General Public License v3.0.

Acknowledgement: We thank Eawag for the financial support of this research (2016-2018).
 

[1] LoRa Alliance. (2015). LoRaWAN What is it? - A Technical Overview of LoRa and LoRaWAN. LoRa Alliance. Online available

[2] C. Ebi, F. Schaltegger, A. Rüst, and F. Blumensaat (2019). "Synchronous LoRa Mesh Network to Monitor Processes in Underground Infrastructure", IEEE Access, vol. 7, pp. 57663-57677. doi:10.1109/ACCESS.2019.2913985.

[3] In-Sewer LPWAN - A synchronous LoRa-based data communication protocol, github