Optimization of Sensor Node Placement for CO2 Concentration Monitoring Based on Wireless Sensor Networks in an Indoor Environment

Indoor ventilation is crucial for human health. For example, as a countermeasure against COVID-19, carbon dioxide ($\text{CO2}$) concentration was employed as an indicator of ventilation timing. In this letter, we discuss the optimal placement of sensor nodes in wireless sensor networks for $\text{CO2}$ concentration monitoring considering the accuracy of observations and the cost reduction. The cross correlation coefficient and relative error, which are indicators of the similarity of time variation and difference of observed values, respectively, are employed as a cost function of optimal placement of the sensors. Experimental analyses are conducted in an actual environment to validate the effectiveness of the proposed method.