Hybrid SUN-LoRa Network on a Low Altitude Platform for Remote Water Quality Monitoring

When implementing remote water quality monitoring systems in harsh tropical environments, several issues need to be addressed in order to achieve reliable data collection from many sensors. These issues include poor coverage of existing cellular-based networks, mountainous terrain and thick foliage which may obstruct line-of-sight, and large transmission distances which may be difficult for some existing wireless technologies. This paper proposes a novel system architecture which employs a hybrid of several existing wireless technologies to address the issues mentioned above. A combination of Smart Utility Network (SUN), Long Range (LoRa) and Wi-Fi technologies are utilized to collect water quality sensor data from a lake in a mountainous rural area. This heterogeneous network is assisted by a low altitude platform (LAP) to overcome the non-line-sight (NLOS) transmission and achieve further transmission distance. This paper reports the drive test results in an actual lake environment to determine suitable node locations for preliminary system verification. Results confirmed that the proposed system could collect data from a sensor in NLOS from the center station by relaying data over a ground distance of 2.4 km using multiple SUN and LoRa devices assisted by an air balloon lifted to 93 m.