Status Update Scheduling in Remote Sensing under Variable Activation Delay

Sensor data exchanges in IoT applications can experience a variable delay due to changes in the communication environment and sharing of processing capabilities. This variability can impact the performance and effectiveness of the systems being controlled, and is especially reflected on age of information (AoI), a performance metric that quantifies the freshness of updates in remote sensing. In this paper, we discuss the quantitative impact of a variable activation delay on AoI. We consider an offline scheduling over a finite horizon, and we show the main role of the first and second order moments of the activation delay. Our analysis gives a quantitative boundary on when such term can be neglected and also prompts possible further investigations that can be used to mitigate the increase of AoI and improve the overall performance.