Age of Information for the Cellular Internet of Things: Challenges, Key Techniques, and Future Trends

With the rapid development of cellular Internet of Things (CIoT), more and more real-time applications appear in our lives, which require timely status updates. To exactly characterize the information freshness, the concept of age of information (AoI) has received considerable interest. In this article, we start by introducing the characteristics and requirements of status updates in CIoT, and some AoI related functions are listed. However, it is nontrivial to realize real-time status updates over wireless fading channels, and we analyze the challenges for meeting AoI requirements. Next, we provide a survey on a variety of status update optimization methods and techniques. In particular, we introduce the prediction technique into the status update systems and propose a novel prediction-based status update scheme. Some numerical simulations are provided to show the performance gain obtained by the proposed scheme. Finally, we discuss some promising directions for future research in this emerging area of study.