Average Age of Information Minimization in an Energy Harvesting Wireless Sensor Node

In recent years wireless sensor nodes (WSNs) have attracted lots of research attentions due to their undeniable role in providing Internet of Things (IoT) services. Due to the large number of sensors, and considering the fact that some of them would be physically inaccessible, using EH methods can be considered as a reasonable powering option. However, randomness nature of these energy sources would affect delay performance of the sensors and this paper studies this issue using age of information (AoI) as a metric to evaluate freshness of measured data. Energy causality constraints have been considered for the assumed system model and average AoI has been obtained for different values of system parameters. It has showed that optimal AoI would be obtained for a particular ratio between measurement and transmission service times and there should be energy arrivals at about 0.45 of total lifetime. It has also showed that EH methods are potential to approach optimal AoI when constant power supply is available with a light difference, which is a remarkable result.