Analysis of Propagation Link for Remote Weather Monitoring System through LoRa Gateway

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Abstract
In this paper, the feasibility of Long Range Wide-area network (LoRa) implementation in remote locations for weather data transmission is discussed. Currently, due to the unavailability of mobile coverage in some rural areas such as in Sabah and Sarawak, local agencies have to subscribe for Very Small Aperture Terminal (VSAT) services to perform data transmission or other applications. For example, VSAT services have been used by Malaysia Meteorological Department (MetMalaysia) for weather data transmission from some remote weather stations to their server. VSAT service is a very reliable solution however, the price is too high. Due to this, LoRa communication is proposed as an alternative solution due to its low-cost, low power and long range characteristics. In this project, a LoRA module was used to demonstrate a single channel LoRa gateway that acted as a bridge to communicate between LoRa node (s) to IP network. The feasibility of LoRa for meteorological data transmission in remote locations was discussed through analysis of current scenario as a case study, and the propagation performance in ultra-high frequency (UHF) operation was determined and validated through measurement of received power spectrum and detailed link budget analysis. Based on the observation from both theoretical and measurement, the power transmitted from LoRa node/module were inconsistent throughout the day due to the changes in spread factor that has been automatically set by the module. Nevertheless, taking into account this factor, it was found that the transmission range was adequate for some remote locations. Meanwhile, for some locations that are separated too far from each other, higher power is needed to allow consistent communication.