A Sigfox Energy Consumption Model via Field Trial: Case of Smart Agriculture

This paper proposes an experimental approximation formula for battery lifetime considering real Sigfox node behavior for smart agriculture as an internet of things (IoT) use case outdoors. To achieve this, a Sigfox-based sensor node is first developed using only general-purpose devices for measuring the current consumption of the sensor node by the user self. Here, the consumed current in the sleep state could be reduced significantly by improving of embedded software and leakage current countermeasures of electronic circuits. Using the node, the outdoor transmission performances such as coverage area and the best position to communicate in a farm house were demonstrated. Next, we analyze energy consumption mechanisms associated with wireless communication of Sigfox nodes and derive an experimental approximation formula of the battery lifetime of the Sigfox node using input parameters from the user and measured values in field experiments, as well as transmission performance results described above. For deriving the experimental approximation formula, we focus on the Sigfox specification, which allows users to arbitrarily set the number of communications (uplinks and downlinks) per day. Finally, we present the impcat of the number of uplink transactions in one day and payload size for battery lifetime using the proposed model numerically. Moreover, we point out that the time- and frequency- and spatial diversity effects, which are important features of Sigfox, which can be degraded because of multiple frame collisions.