Update rate, accuracy, and age of information in a wireless sensor network

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 introduced in this thesis to assess how close the information estimated by the destination is to the information monitored by the sensor. The mean squared error (MSE) between the estimate and the information being tracked by the sensor is used to evaluate the accuracy of information. In this thesis, we consider a single-sensor wireless network with this sensor monitoring a time-sensitive physical process, which is modelled as a random walk. The update scheme is that whenever the state of the underlying random walk changes by more than a specified amount, the sensor generates a status update packet and transmits it instantly to the destination over an error-free channel. When there are no status updates, the destination assumes the status is the same as what it received most recently. We address the problem of finding the minimum update rate under AoI and accuracy of information constraints. More specifically, we develop methods to derive analytical expressions for the three metrics: the update rate, the AoI, and the MSE. As expected, the AoI and the MSE decrease with the update rate. The analytical results are verified by using Monte-Carlo simulation experiments.