IoT Definition
The Internet of Things (IoT) is an emerging digital fabric that will tightly integrate our physical world into computer networks by connecting billions of things, such as small
sensors, wearables, vehicles, and actuators, to the Internet.
Components of IoT Network
An IoT network consists of three main components:
i) IoT devices: usually deployed to observe some physical characteristic of the environment for a certain geographical area, e.g., temperature, pollution levels, or humidity.
ii) communication network: network channels
iii) destination nodes: the data measurements are processed to extract meaningful information, e.g., controllable output decisions or remote source reconstruction that can assist in the prediction of its information status evolution.
Clearly, the accuracy of such output decisions, which determines the performance of IoT-enabled applications, is directly related to the freshness of the aggregated data measurements of the IoT devices at the destination nodes.
How to judge the freshness of the information received at a destination node?
Particularly, the duration of time over which the information status at a destination node is still considered fresh is dependent on the application for which IoT devices are being used. For instance, this duration can be relatively large if the IoT devices are deployed to sense temperature or humidity, whereas it may be very small for human safety applications.
The necessity of charactering the AoI
The energy-constrained nature of the IoT devices along with network congestion increase the likelihood of packet loss or out of order reception, which in turn reduces the value of update packets received at the destination node and results in wastage of resources due to obsolete transmissions. It becomes even worse for far-off IoT devices whose direct links to the destination nodes may be very poor [9]. This necessitates the need for characterizing AoI for these networks.
[1] Abd-Elmagid M A , Pappas N , Dhillon H S . On the Role of Age of Information in the Internet of Things[J]. IEEE Communications Magazine, 2019, 57(12):72-77.
