LoRa-Based Multi-Hop Network for Smart Water Metering Devices

Smart water metering deployments require low-power, large-scale communication infrastructures that existing LPWAN solutions do not fully address. Among the most widely used technologies, LoRaWAN's single-hop topology requires dense gateway de-ployments in urban environments, while cellular alternatives incur subscription costs and higher energy consumption. This paper presents a multi-hop LoRa network protocol spe-cifically designed for smart water metering, exploiting the static network topology and uplink-dominated traffic pattern of this application to substantially simplify the protocol design. The protocol constructs a tree rooted at the gateway through distributed relay se-lection. Each node selects its relay using only lightweight message exchanges and a cost function that combines hop count, relay load, and link quality, requiring only local infor-mation and no global routing tables. Explicit acknowledgements are replaced by over-hearing relay retransmissions, further reducing energy consumption. The cost function coefficients were tuned through simulation using Bayesian optimization across network sizes of up to 100 nodes, revealing that the optimal parameter configuration is itself net-work-size dependent. Compared with a shortest-hop (BFS) baseline, the proposed ap-proach limits the maximum relay load to approximately 12 client nodes regardless of network size, achieving a reduction of up to 72% in the 100-node scenario while incurring an average hop-count increase of up to approximately 13%.