Evaluation of Energy Consumption and Battery Life Span for LoRa IoT Multisensor Node for Precision Farming Application

In this paper, evaluation of energy consumption and battery life span for a long-range (LoRa) Internet of Things (IoT) multisensor node for precision farming application is presented. The energy consumption model consists of analytical expressions for the determination of the average current drawn per cycle, the energy consumed per cycle, and the battery life span. The case study multisensor node has five sensors for capturing data on the temperature, relative humidity, CO₂, soil moisture, and light. A program written in Visual Basic for Application (VBA) was used for sample numerical computations for the case study multisensor node operated with bandwidth of 125 KHz, transmitter power of 10 dB, cycle time of 540,000 ms, and spreading factor of 12, 11, 10, 9, 8, and 7. The results show that the average current drawn per cycle increases with increase in the spreading factor, the energy consumed per cycle increases with increase in the spreading factor, while the battery life span decreases with increase in the spreading factor. Furthermore, for the spreading factor of 12, the active states took about 43.89% of the cycle time and consumed 46.76 5% of the total energy per cycle, whereas, the sleep state took 56.11% of the cycle time and consumed about 53.24% of the total energy. In all, the idea presented in this paper is relevant for researchers that are working on modeling the energy consumption in multisensor nodes which are popularly used nowadays in smart system design.