A Study Regarding Power Consumption of An IoT Node For Image Retrieval and its Optimization

This paper analyses the power consumption of an IoT node that captures images and transmits them to a cloud storage. Various implementation versions of the IoT node are proposed, focusing on the utilization of common components to achieve cost-effectiveness and minimize the maintenance requirements. The realised node variants were initially tested in laboratory conditions and then commissioned and deployed outdoors, being located in an orchard where they remained operational during 7 months under different meteorological conditions. The proposed solution utilizes an ESP32 microcontroller and a camera with a resolution of 1.3 Megapixels as a data acquisition node whose energy is assured by a Li-Po battery, charged through a solar panel. Wi-Fi communication was employed to transmit the images to the server. The power consumption of the node was evaluated for different variants of software optimization using the HTTP or the MQTT transmission modes. The instantaneous current consumption of the nodes was measured in laboratory to identify the power consumption for each phase of the program execution.

The experiments revealed that the MQTT transmission mode consumed considerably less power than the HTTP mode. Additional experiments have been performed in which the variation of the battery voltage, the solar panel voltage and the number of daily emissions in the examined period, as well as correlations between these quantities have been analyzed.