Update Rate, Accuracy, and Age of Information in a Wireless Sensor Network

Abstract: Age of Information (AoI), namely the time that has elapsed since the most recently delivered packet was generated, is receiving increasing attention with the emergence of many real-time applications that rely on the exchange of time-sensitive information. AoI captures the freshness of the information from the perspective of the destination. The term "accuracy of information" is used to assess how close the estimate at the destination is to the parameter value measured by the sensor. In this paper, the mean square error (MSE) is used to evaluate the accuracy of information. We focus on a single sensor that monitors a time-sensitive physical process, which is modelled as a random walk. Whenever the state of the random walk changes by more than a specified threshold, the sensor generates a status update packet and transmits it to the destination. When no update packet is received, the destination assumes that the state of the process has not changed. We study the problem of finding the minimum update rate under AoI and accuracy of information constraints. More specifically, we derive analytical expressions for the update rate, the AoI, and the MSE.